[FutureBuddha (Hunches XIII)] The Mammals

**Jundo** · 10-24-2024, 08:30 AM

I added some paragraphs above describing the impact of the great meteor ...

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As every school child knows, the reign of the dinosaurs ended with a great meteor’s fall some 66 million years ago. In the long winter which followed, our warm blooded line survived and thrived. Many others did not.

Perhaps no other event symbolizes more clearly the fortuities upon which our current lives rest.

... Several theories exist about the giant’s start, how it was slowly pulled toward Earth. It likely existed from the earliest era of our solar system, a bit of flotsam left over from the formation of the planets, a straggler tumbling in the void. It was certainly itself the product of chance impacts with other objects, time and again, in the great pachinko parlor of space. Most such bodies can be found in the great asteroid belt between Mars and Jupiter, circling the Sun in various, often wild orbits. Almost all stay far away from here, pose no threat. Sometimes, however, there are exceptions whose impact can truly change the game.

What eventually sent the beast our way is far from clear. The immense pull of Jupiter’s gravity can slingshot objects from the asteroid belt, exerting a strong yet subtle influence that sends them hurling toward the inner system. Or, some suggest, a sudden collision with another large object can cause a fateful turn, like a kid’s game of bouncing marbles. Whatever the reason, the disruption would have happened millions of years before eventual crash into our world. The meteor would first spend ages in elliptical orbit around the Sun, sometimes crossing the course of our Earth and the other inner planets, but always (until the fateful day) passing safely by. The Sun, the other planets and our own gravitational nudges sometimes pushed and pulled the object ever so slightly in its millions of years of travels, as might additional small impacts with other like bodies. By such influences, its course was lightly prodded here and there. The cumulative effect of the chance happenings eventually lined up our world as target.

Our fate has been determined by tumbling dice in space.

As it approached Earth, and especially in its ultimate pass, this planet’s gravitational grip became strong, crossing the point where Earth’s attraction exceeded the influence of the Sun, accelerating the mass and pulling it toward Earth’s atmosphere. Velocity increased, finally approaching 20 kilometers (12 miles) per second near the moment of impact. At such speeds, the air in front of the incoming visitor will be rapidly compressed, the effect generating intense friction and heat reaching several thousands of degrees. Smaller objects will burn up completely in such conditions, but for a meteor this large, only its outermost layers will have vaporized. The amount that remains determines what follows.

On contact, the energy released may have been equivalent to 10 billion Hiroshima A-bombs. ... Winter covered the planet, lasting months or years. Cold, starvation and biting acid rain were the result, changing the nature of land and sea, with worldwide ecosystems disrupted.

Some swimming and flying life made it, others did not. The situation was too much for many large and hungry animals, especially the cold blooded. On the other hand, smaller land animals, especially if warm blooded, could burrow or hide away. Some were the early mammals.

Your ancestors were among these survivors.

Sadly, what was very good fortune for our ancestors was not so for all, nor for their prospective descendants who were denied a chance to be. Many species died out, vanished from history, while our line carried on. The events on this world truly can be cold blooded, filled with perilous crossroads of life and death, mercilessly cruel to some but forgiving of others, cleanly dividing winners and losers in the battle to endure. Individuals, whole herds and entire kinds are separated between weak and strong, hunters and hunted, slayers and slain, genetic successes and wiped out failures. Nature gives and takes away, sorts and separates with harsh and heartless power. Our personal existence today rests on the burned ashes of others, including in more recent millennia, the bones of fellow human beings who died while others did not

I never wish to imply in this book that the amazing road which led to your living, dear reader, was always a peaceful one. Fate is eventually fatal. We will return to the philosophical implications of that fact in a later chapter.

But as the planet warmed again following the great calamity, the momentarily unbalanced ecosystems found their balances again. The age of the mammals, our age, had begun.

**Jundo** · 10-24-2024, 09:23 AM

I also greatly rewrote the section hinting that there is something more to evolution than meets the eye. I will underline key changes in the following ...

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TAKING STOCK

Before we move on, I would like to take stock of where we have come, and recall the central point of my argument. In the pages that follow, we will see our own body types gradually manifest, recognizable more and more clearly in our ancestral species. Various mutations and changes in body and brain appeared over millions of years, increment by increment, and those which tended to facilitate survival tended to remain. That does not necessarily mean that natural selection had human beings in mind in doing so (let alone you in mind, dear reader) . In fact, all adaptations are responses to the conditions at the time, not the future (e.g., a new foot structure appears in an individual which aids survival during their lifetime, and thus increases the likelihood of its being passed to the individual's children. According to our present understanding of evolution, it is not that the new foot structure somehow manifests with future generations and their future survival in mind.)

Nevertheless, the same puzzling fact presents itself:

It remains the case that you, dear reader, are unlikely to be you, right now reflecting back, unless each and all mutations in your particular ancestral line had done so with the specific content, sequence and timing they did. A failure to appear, or appearance somewhat otherwise, or appearance in a different familial line, or appearance in a different generation, different brood or even different individual could be expected to set genetic and historical events off in a very different direction ... one away from eventual you.

In other words, you are you because evolution wound around to you just right, most precisely, with the right ancestors and right on time. The fact that you are you now is more than sufficient proof for the assertion that all mutations necessary for you did indeed happen, bar none, with the needed content, sequence and narrow timing required to wind up as you. Had a needed mutation not appeared in an ancestor, had the ancestor not passed on the trait in the right generation with the right partner in the right mating at the right moment, you would not be you, and perhaps, would not be anything at all.

Is it possible that both truths might be true at once?

Is it possible that an as yet unknown mechanism might exist to explain the outcome amid seemingly chance events? I believe so.

After all, there are plentiful examples in our world, including in nature: Migrating birds and fish cross great distances, stopping here and there amid changing weather, enduring surprise obstacles and chance encounters along the way, yet hone in on specific breeding grounds. Seeds scatter wildly in the wind, landing here and there, only some finding fertile soil, yet a particular seed so landing will give birth to its particular tree. A seemingly random meeting of sperm and egg begins a process not so random, with a baby of 10 fingers, 2 arms and 2 legs, 1 nose, 1 heart and 1 brain the expected outcome at the other end (generally not a child with any wild combination or absence of those things.) In all these examples ... animal migrations and returns, scattering seeds, gestating babies ... nature has found mechanisms to change random events into processes less than random, with certain outcomes largely fixed and predictable. However, so very mysterious did these events appear to the ancients before we came to understand better the seeming ability of some creatures to follow the Earth's magnetism with the season, the nature of tree growth, the workings of DNA, RNA and the like. What appears largely random is far from totally random at all.

Could an as yet unknown pattern or seed for 'you being you' be the same?

The jury is still out as to whether there is some direction to natural selection, e.g., toward general intelligent life. Certainly, science currently disfavors the notion of some process with specifically homo sapiens (let alone you and me) in mind. Nonetheless, it seems extremely doubtful that the wild, complex, spinning gambler’s wheel of mutation and mating would have spun around … again and again, again and again … through millions and billions of years into the exact outcomes needed for you, trillions of spins after trillions of spins, the silver ball always falling in the correct hole. But it happened.

Nor were the changes necessarily smooth and orderly or all at once. Mutations might happen suddenly, even if after long periods. Or, evolution can happen gradually, with incremental changes very much unlike the final outcome (the human inner ear’s evolution from piscine dental and jaw changes is such an example.) Evolution may sometimes “back-track,” going in reverse for a time as new characteristics vanish again (the return of some mammals to the sea as dolphins and whales is such an example.) Some changes, otherwise beneficial, may also carry enhanced risks (e.g., a mutation with one benefit which also increases the risk of a certain genetic disease.[1]) Helpful mutations may appear, only for the carrier to die before having a chance to mate and pass them on. Also, like mutations may appear repeatedly in disparate creatures of the same species, or in very different species, such as manifold versions of eyes which have independently evolved many dozens of times with unique structures in species ranging from vertebrates to scallops to flies. Some characteristics, such as an ability to walk upright, did appear (as you yourself evidence each day by your own walking), but the timing of the first appearance of that ability in ancient pre-human hominids could have varied by millions of years.

Nonetheless, by your very life and abilities, we can be assured that the traits necessary now for you to be you did appear, and with the right timing and right individuals in your ancestral line to have allowed you to be you. An example is upright walking in your pre-human ancestors, all as proven conclusively by your rising now and taking a few steps.

Can a mechanism exist by which both facts are true at once?

Many a computer program, assigned a desired task (e.g., to find a pharmaceutical compound to do X) will attempt a variety of combinations, crazy patterns, hits and misses, before honing in on certain promising or likely directions. From outside, its doing so may appear far from smooth and orderly, with patterns manifesting suddenly, but sometimes gradually, back-tracking, producing unexpected side-effects, results overlooked at first, parallel compounds that each do much the same thing. Nonetheless, if left running, there is a good chance that the A.I. will eventually arrive at X. To the ignorant observer, unaware of the experiments within the black box, and the mathematics behind it, what will be seen is little more than a button pushed at the start, followed by result X that appears to pop up magically at the other end.

Just because a process is not known, that does not mean that the process does not exist.

However, one thing appears clear: The world might have done without homo sapiens.

Looking at all the other species which reside in this world, from bacteria to bears, amoeba to aardvarks, condors to crabs to cockroaches, mice to monkeys … there is no reason that the Earth could not have carried on just fine (maybe even better) without humankind. Looking at all present, past or prospective options that are not you, it also seems that the Earth could have carried on wonderfully without you most specifically. You, on the other hand, could not have carried on without humankind, for you are a human.

This book finds something possibly significant in there being human beings, especially as you and I, dear reader, find ourselves presently and most immediately self-aware of being so. We are not bacteria or bears, amoeba or aardvarks, condor or crab or cockroach, mice or monkeys … nor, does it seem, could we be self-aware of being ourselves were it so. Everything has lined up precisely, mysteriously, since the start of evolution (nay, since the start of time) to allow this moment of self-experience. I propose that there is something more to the strange outcome.

So, with that in mind, let us now walk the path that wound from our first, tiny, mousy ancestors to your steps now.

**Jundo** · 11-17-2024, 02:35 PM

I have finished the chapter on natural selection, the hardest to write. I have decided to post the entirety here. I make every effort not to fall into the errors, misrepresentations and misunderstandings of natural selection and mathematics that many of the so-called "intelligent design" folks fall into. I am very skeptical of their arguments.

My point is much simpler, based on the strangeness that every single mating and mutation, without a single miss, worked out perfectly for billions of generations (nay, trillions of generations if you include your ancestral microbes) were you to be reading these words now. You are sitting at the current end of an unreasonably long winning chain of luck.

(Just a note that footnotes are no completed, and are just placeholders now)
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CHAPTER 11
YOU-VOLUTION

This is life’s saga, told from the most personal of perspectives -

It chronicles the fine biological steps, the most precise twists and turns of evolution, that would have needed to twist and turn were you to be you.

Since you are you (I assume you agree) we are justified in concluding that each of those steps and turns was stepped and turned, all precisely and in proper sequence, not one amiss for millions and billions of ancestral generations - for otherwise we’d now be missing you.

Are we missing something if we overlook the supreme unlikelihood of the chance result in you, an outcome which you can confirm this moment, firsthand, just by breathing?

Seemingly, it need not have been so: Events could have turned a slightly other way at any point, and the world would have moved on without you. Nonetheless, events never did, never once.

In this chapter, I will recount but a tiny fraction of what had to happen along the tangled trail, crisscrossing from life’s first conception on Earth to your conception in your mother’s womb.

In doing so, my intent is not to challenge the demonstrated truth of natural selection and evolution. I fully believe in Darwin’s theory. However, I question whether its grand vista has been fully explored. I simply wonder at the implausible extent of survivors’ luck needed, generation after generation, for us now to be this you and us. Is there more to the process as yet unknown, much as the mechanism behind the diversification of species was itself unknown until Darwin’s great insight? Charles Darwin’s writings made obvious a system of change based on mutations contributing to survival, a phenomenon once misunderstood as miracle or magic. His discovery replaced open chance or divine providence as explanation for the variety and adaptation of life on Earth and the complexity of these bodies we inhabit. However, is there something more to the process that reduces further the elements of chance?

Sometimes what is true on one level is not the full story, much as the mechanism of heredity observed by 19th century Darwin remained mysterious in its workings until the 20th century discovery of the double-helix, all as further amended by our current understanding of epigenetics.

Is there something more to the rowdy struggle of fortuitous survival?

Obviously, the human species had potential to evolve from its long line of progenitor species given the fact that – we humans can verify – we did just that, the result of eons of nature’s experiments. Darwin surely had it right.

But did Darwin have it complete?

Does his theory need to itself evolve, into a wider explanation of how things worked out so well … so outlandishly and improbably on the money … at least from your and my perspectives as the absurdly unlikely survivors in our generation?

There is a missing link in natural selection: What is missing is clarification of how a random, violent, shifting and wild sequence ran along randomly and wildly right to where you need it now for you to be you. How did a meandering march set your own heart a’beating - not missing a beat in billions of years along its way? What were the odds that every “survive or die,” “kill or be killed,” “fight or flee,” “meet then mate,” “birth and growth,” avoidance of death and extinction crossroads of life’s advance, without exception, would survive, kill, fight, flee, meet, mate, birth, grow, exist and advance just when and how all would need to do to arrive at you (me too)? Is it just another case of most obscene luck, like everything else that has occurred since the Big Bang to set your place at the table, spoon in hand?

No, my purpose is not to deny evolution. In fact, I celebrate it.

But let’s play a little game, just for fun:

All we will do in the game, in the coming pages, is pull out pieces, one by one. We shall ask just what bodily parts and abilities needed to evolve so precisely, what could not have been done without or in ways much otherwise, in order to have the current result, namely, your being alive and curious about your being “you.” We will ask whether even small alterations in evolution’s course would have prevented the present result of you. We will then wonder at how evolution’s meander might have wandered elsewhere at any minute moment, and at how fragile and ephemeral is each link of the chain upon which your life hangs.

We will admire, not merely at how life came to be at all, but at the fluid and fickle trail to our specific species and the qualities we possess, almost all of which are necessary to allow us to be experiencing our humanity in this instant, able to reflect back down the fantastic minefield of “endurance or death” successfully traversed by billions of generations of our genetic ancestors (millions of generations since the first primates alone) without a single miss.

I apologize for the game being, unavoidably, a little gruesome: However, we will cut away bits of you, remove internal organs, extract eyes and ears, dispose of limbs, shave away the lobes and hemispheres of your brain, drain blood, peel flesh and extract cells one by one until the possibility of human life will have vanished (that will happen quite quickly), until consciousness of being “you” could not be. Then, witnessing the evolution and birth of each cell and whole organ, ounce of blood and inch of flesh, we will look at how lucky you were that it all went right, all fitting together just right for you to use.

The story will highlight both that (1) all aspects of the human body that needed to evolve and become inheritable if indispensable to your life today did just that over time, nary a miss, and (2) the precise and inflexible causal chain containing your specific personal ancestors, from primeval pond to prokaryote to piscine to primate to people to your personal parents, including all genetic mutations and subsequent cellular divisions or matings to pass on those genes, must have occurred in most specific sequence, with extremely inflexible timing options, to enable your conception and birth, all as proven by your life right now.

In other words, if a single cell were late in a timely split, if any ancestral amphibian missed an essential mutation, if one monkey failed to mature and do its “monkey business” if in your genetic line, you would not be here.

According to today’s most commonly accepted understanding of life reproduction, if a single ancestor or pair of ancestors in your familial line of heritage had failed to themselves be born, to carry a very specific genetic coding, to reach adulthood and to mate with most meticulous timing so as to permit two specific gametes to unite … even if in only one single generation contained within your personal ancestral line stretching back billions of generations across billions of years … then you would not be alive now to consider that lineage. Given our present conception of evolution and genetic inheritance, if any one hereditary grand-parent, from the earliest cellular organism, or in any generation of ocean life or land life, including fish life, amphibian life, reptilian life, mammalian life, primate life as well as all human generations, had failed to divide (for cells) or meet and mate in a most ‘right on time and right in place’ way, then you would not exist right now. Some other creatures might have been born instead (or no one), but seemingly not you if your personal familial chain had been broken at any link. The fact that you do exist, however, thus implies either incredibly good evolutionary fortune (possible, of course, but also profanely, absurdly doubtful because of the foolish odds again’ it), or instead, that there is some aspect to the process which shortens the odds in a way not yet fully understood.

And that is the whole game

The great biologist and explainer of evolution, Richard Dawkin, says it best:

The instant at which a particular spermatozoon penetrated a particular egg was, in your private hindsight, a moment of dizzying singularity. It was then that the odds against your becoming a person dropped from astronomical to single figures.

The lottery starts before we are conceived. Your parents had to meet, and the conception of each was as improbable as your own. And so on back, through your four grandparents and eight great grandparents, back to where it doesn’t bear thinking about.[1]

But perhaps it does bear thinking about.

Yes, it might just have happened to happen that way.

Yes, if some creatures had to evolve, it might as well be your kind instead of another.

Yes, if nature had to come up with something, that something might as well have been vous et moi.

However, our lives are built upon a biological house of cards. Our place, perched upon the elaborate, layered stack appears most fragile. Looking at the grand diversity that nature has brought forth on our planet (putting aside the good fortune that there is an Earth, and that it hosts life and evolution at all), we can ponder the innumerable directions that evolution did go or potentially could have gone without us in the picture: from single-cell life to worms and ants, to whales, plants and trees, birds and bees, as well as untold potential species and individuals that might have been but never were. Species come and go, appearing on the Earth, thriving for a while, then most eventually extinct and defunct. As we presently conceive of evolutionary history, there seems no particular reason that intelligent life had to manifest at all (the planet made do with simpler life for billions of years). Nor was there apparent inevitability that, even should intelligence evolve, homo sapiens had to be the intelligent species, let alone that you had to be one of those homo sapiens.

Looking at all the alternative body types found on this planet, there seem no particular need that homo sapiens had to evolve, having all the bodily and mental trappings and abilities that go into being homo sapien … instead of sticking with homo neanderthalensisor homo erectus, or keeping to hippopotamus amphibius, flying serinus canaria, crawling blattella germanica or the green and mossy leurozium schreberi. One would think that natural selection could have selected those species or some others, then gone that way not our way, never bothering at all with personalus nos (personal us)!

But it is good for sapien you that homo sapiens did evolve our complex body and sapien brain, for it is inconceivable that you could be you under almost any other evolutionary circumstances, even if a better swimmer or flyer, dirt crawler or tree climber, or more fragrant and lovely in bloom.

In the coming pages, let’s pull out cards, one-by-one, and watch the tower fall. We will think of the myriad steps, any single step, in the course of human evolution that could have prevented your being & thinking about those myriad steps …

… thinking of all that drifted your way since your first ancestor drifted in a bog.

OOZE TO LUCA

Stuff born of the Big Bang, shaped and reshaped in the interiors of countless stars, collected in prehistoric tidepools on our world – puddles of goop and ooze.

But not just any goop and ooze, mind you … and not just any puddle. Somehow, there fell to Earth and gathered the special mix of substances, in the specific place and time that, with a little zap and bit of a shake, bore the spark of life.

What is more for our purposes: It was our spark of life, our original zap or shake. Though such a mix might have mixed on countless worlds … or at other places and times on this world … our lives likely required a certain place and time for the fire to catch. Why? In fact, most theorists theorize it a once in history sparking.[2] But even if not, we logically needed a goop and ooze to precisely ooze from the place and time we’ve needed, not some place and time that would have done us no service because oozing off otherwise. Only in this way could begin the slinking causal chain that wound around through the years to here (demonstrated by the fact that we now sit at the current other end of that chain.) It wasn’t just any goop on any globe, not any torpid tidepool on this globe, nor simply any zap and shake … but the specific ooze on our orb, zapped and shaken just right – not too early, not too late – to the very degree and direction that trickled down to us. We can logically assume that any other pool, or a different zap or shake, would have set things off on a dramatically different routing … toward other creatures, or no creatures at all.

Thus, because our chance for life might have seeped away … because the mix could have gone unmixed, the spark unsparked, or down some alternative treacly track … we must marvel at our murky miracle of mucky luck.

And not just any muck.

For we evolved from what was, in bio-chemical terms, a most mysterious muck – that special mix required in setting the stage for all earthly life, with ingredients that were themselves the product of all that had come before during the first 10 billion years of the universal history.

We’ve seen in prior chapters the many hoops that the universe jumped through in producing the basic elements, especially the higher elements from carbon on up. However, that having happened, the four elements – hydrogen, carbon, nitrogen and oxygen – that comprise by weight over 95% of all living matter on Earth, are also the four most abundant non-inert elements in the universe. As they are so plentiful in the cosmos, it may seem not surprising that life on Earth began from the most abundant materials at hand.

Except for the many more hoops that life yet had to pass:

First, the Earth-birth, about 4.5 billion years ago, was violent and hot. This orb’s slowly building mass was pummeled by the flotsum and jetsum of the solar system – asteroids, meteors and comets. That is good, as those space invaders brought with them the four basic elements, as well as the rest of what would eventually make us, the calcium and phosphorus, chlorine, sulphur, sodium, magnesium, iodine and iron - plus minute traces of manganese, molybdenum, silicon, fluorine, copper, zinc and a few more. However, the space impacts also put the planet on the boil. The heat of those smashes, combined with our world’s own internal furnaces, kept things at searing heights for a very long stretch. Could life have gained a toehold in such violent conditions? Most scientists think not, with the Earth first needing to cool considerably for life to start and hold on.

Next, the basic elements present on Earth could not be just their simple selves if generating life. Rather, they were fortunately present in the form of reactive substances produced by their mixing and combining: methane (the elements carbon and hydrogen as CH₄), ammonia (nitrogen and hydrogen as NH₃), water (hydrogen and oxygen as H₂O), hydrogen sulfide (hydrogen and sulfur as H₂S), carbon dioxide (carbon and oxygen as CO₂), and phosphate (phosphorus and oxygen as PO₄). Although the exact mixes and percentages are open to guesswork, all those compounds are thought to have been common on early-Earth.

Because of the tremendous change and tumult on the infant Earth, no geological samples exist of our globe’s initial 500 million years. Whatever crust might have congealed from time to time all melted away time and again, or eroded, or was absorbed by geologic movements. Thus, even if life caught its spark during the period, traces of its origins on this world have vanished. We possess fossil records dating back over 3 billion years, but nothing beyond, nothing from the first moment life sprang up from apparently lifeless matter.[3]

In fact, we do not yet know for sure the precise mechanism that got life kicking on Earth. There are various theories, including those which posit a “primordial soup” in which the methane, ammonia, hydrogen and water swirled together and were energized by lightning, UV radiation or perhaps volcanic activity. The resulting reaction may have led to simple organic molecules, such as amino acids, then proteins, nucleic acids and, eventually, early cells.[4] Other theories propose the mixing of chemicals near hot, hydrothermal ocean vents, or on the surface of clay. It is also proposed that existing life or the building blocks of life fell from space with 'panspermic' comets or meteors, like extra-terrestrial seeds carried on the wind, ready-to-go and grow upon finding hospitable soil. [5] Amino acids and other organic molecules have been found on meteorites that we have sampled, while some microorganisms could survive (theoretically) even amid the harsh conditions of space. There are other theories regarding life’s start on Earth too.

Experiments since the 1950’s have demonstrated that when methane, ammonia, water and such are placed in a jar, then shocked with electricity or similar force, amino acids and other organic molecules are created.[6] That may imply that energy stimulation of those molecules – possibly by lightning or ultraviolet radiation or pressure waves caused by impacts from space – could have given rise spontaneously to basic life building blocks. Somehow, an ancient admixture may have birthed basic monomer molecules (amino acids, for example) that themselves serve as raw materials for more complicated polymer molecules (such as proteins, formed of long chains of amino acids).

However, to date, getting to life’s complex polymers from simpler monomers seems not such a simple thing, and no one has yet done so in a laboratory.[7] Also not yet understood are the additional steps by which “not alive” organic molecules then became self-replicating life forms. Some theorize that, over time, a very special molecule may have formed by hit and miss, a molecule with the unique talent to copy itself, perhaps using as assembly parts bits of other molecules in its environment.[8] Perhaps that marvelous molecule was something like viruses today, not quite alive yet able to reproduce and multiply. There are other competing theories too. Nobody really knows yet.

But in any case, all that happened.

Somehow and someway, like Frankenstein’s monster, dead stuff came to life.

Although much guesswork is involved and it is hard for us to know exactly how, when and where life got going, – by looking in the mirror – we know for sure that it did. Furthermore, based on our lives alone, we can make certain suppositions about events:

For example, since we are here to look in the mirror, we can know that whatever occurred possessed chemistry having a mix of elements giving rise to resultant features as would be needed to let us be an eventual possibility. Otherwise, logically, initial conditions could never have led to us. Given our common ancestry, that chemistry was such as to lead to all Earth’s other creatures too, for all life on this world shares in our most fundamental features and make-up.[9] Furthermore, the early chemistry must have also had the potential for intelligent life, since we are now intelligently considering that fact. Thus, looking in the mirror, we can be confident that early organic molecules and biomolecules, very fortunately, had that potential to eventually evolve into structures with emergent properties permitting higher-order life among all other life on Earth, for otherwise we would not now be this higher-order thinking about it.

I do not mean to imply that intelligent life was inevitable, or anticipated from the start (that remains an open question, to be addressed later in this book), but at least the possibility had to be there. Somehow the muck became microbes, then monkeys and man.

In this way, your being alive has evidentiary and predictive power useful to any researcher seeking to extrapolate the characteristics surrounding life’s origins and early life. Namely, whatever was the chemical mix from which we arouse, and however the first generations of lifeform which followed, each had to be of a nature that would later enable your life today. We can eliminate as candidates any scenario which would preclude your life.

You should easily agree.

Eventually, life on Earth built up from simple origins, gaining complexity and diversity. But at its earliest stages, there seems to have been barely anything about it to separate life’s chemistry from inanimate matter, the living lumps from the lifeless lumps.

Where is the borderline between life and non-life? We know that a rock is not a rose or rabbit, but at its simplest levels the dividing lines can be quite blurry.

Most experts on the subject say that the question has no straightforward answer. The common characteristics of living matter on Earth – growth, movement and decay, for example – can be found in nonliving matter too. Any lava flow or icecap will do all that. Fire will reproduce itself flame to flame, and certain crystals evolve and adapt over generations.

While ambiguities still remain (in the cases of viruses, for example), scientists have generally made the point that what distinguishes life from the lifeless is an ability to grow, move, decay, both reproduce and evolve.

At some point on our world, matter crossed the fine threshold.

The scientific consensus is that all life on Earth evolved from a single common ancestor, known as the Last Universal Common Ancestor (LUCA): Somewhere, at some time, a single, simple lifeform was the grandparent to all our lines, becoming everything from bacteria to birds to beetles to bobcats to human beings. Evidence for LUCA is found in the fact that all living things share the same basic chemistry and genetic code, for it would be almost impossible for two or more separate lineages to independently develop the specific, complex biochemical structures that all life on Earth shares. Statistical analysis places LUCA somewhere back about 4.2 billion years ago.[10]

Whatever were its beginnings, we have seen that the earliest common ancestor owed its own existence to the chain of seemingly chance events that led to it … all the chemical reactions and pre-biological events commencing when this planet formed (and the Big Bang before that): the interactions, splittings and mergings, that were the chemical predecessors of our first common ancestor. With LUCA, that was followed by even more interactions, splittings and mergings as earth life’s central evolutionary branch got going on its way.[11]

In other words, however life got started and whatever the exact processes involved, fortunately for us, it did so down the very narrow path which later proved necessary for us, and not any other way.

While the mechanisms are little understood, monomers became polymers, and – somewhere by-and-by – their products set to reproducing, self-replicating with sufficient speed and diversity to allow evolution’s taking hold. Change and innovation was at hand, among the most recent of which innovations are found us.

Life was off to the races.

THE SINGLE LIFE

The first matter on Earth that we can truly call “alive” were single-celled organisms, most likely resembling the simplest life forms on modern Earth, the prokaryotes, tiny bacteria and archaea. These single-celled organisms possess relatively few parts: typically a cell membrane without a membrane enclosed nucleus, a dab of cytoplasm and scattered ribosomes. Reproduction was quick, asexual, primarily through binary fission, splitting in two. Early prokaryotic DNA was present, often as a single, circular chromosome. These early beings would have had to be sturdy creatures, capable of survival in the extreme conditions of the time, amid still high temperatures and environmental acidity. By necessity, since oxygen was not yet plentiful on young Earth, they were likely anaerobic. Thus, their energy sources would have to have been chemosynthesis (using chemicals in their environment such as found in acidic hot springs), thermal energy from vents, or anoxygenic (non-oxygen producing) photosynthesis. As we saw in a prior chapter, eventually, a subgroup came to evolve oxygenic photosynthesis, stimulating a boom in oxygen on our world around 2.4 billion years ago.

Given the harsh environment of the early planet, and the speed of single cell reproduction, these simple creatures would have been subject to intense natural selection processes. Generation after generation passed quickly, sometimes in hours or even minutes. Even so, radical change was slow.

Sex was still a long way away. Life was thus simpler back then, in many ways.

However, while not quite sex, a boost occurred during the first billion years of life’s existence, with the appearance of horizontal gene transfer, the ability of organisms to exchange genetic material between themselves, rather than only directly from single parent to immediate child. Such criss-crossing transfer of genes across different species significantly sped up evolution and adaptation. Organisms could sometimes acquire beneficial genes from other organisms without waiting for slow, gradual mutations. Bacterium Type A, for example, could acquire from Bacterium Type B a gene facilitating photosynthesis without need for Type A’s own line to independently evolve such ability, allowing the process to quickly spread. The exchange could happen in several ways: Genes might be absorbed by direct cell-to-cell contact, or from loose floating material in the surrounding environment, or through infection by carrier viruses acting as intermediaries.

Then, in time, things got a lot more complicated …

EUKARYOTES

It sounds easy in hindsight, yet required much waiting, perhaps 2 billion years from the dawn of first life. Like life’s initial spark itself, some researchers believe this further event so rare as also perhaps but once in Earth’s history. Two separate life forms accidently merged, and then stayed merged for all future generations of evolution. Their lucky union gave rise to eukaryotes, complex cells with internal membrane-bound organelles, including the nucleus and mitochondria.

We human beings, and all complex earthly life, are heirs of this union.

The rarity of the event is due to the requirement that several steps and unique conditions occur simultaneously, a confluence of happenings that is most unlikely. It seemingly began as a symbiotic relationship between two single cell types with complementary characteristics. One cell of simple structure, lacking internal organelles, may have begun to evolve certain complex features such as internal membranes. At some point in time, that simple cell may have engulfed an oxygen-using aerobic bacterium. Usually in such cases, the host will dissolve and digest the invader. However, in this case, the host did not, and a mutually beneficial relationship arose between the host and its new tenant. The latter’s use of oxygen for energy may have provided energy to the host amid our planet’s rapidly developing oxygen-rich environment. If oxygen had not become prevalent in the environment by then, it is unlikely that the new arrangement would have been viable. Then, over time, the guest lost its identity as a separate being, instead evolving into mitochondria, the energy producing organelles within complex cells.

However, that change was not a snap:

A stable relationship had to arise between the host cell and the engulfed bacterium where neither was destroyed, both benefitted, both could divide with ballet-like synchronicity, then repeat as they continued into future generations maintaining their fragile new affiliation. Generations of the guests were born and thrived within generations of the hosts. Very gradually, their genetic and biochemical structures merged. Once the relationship between host and guest had stabilized, other cell structures evolved (such as a nucleus, holding the cell’s DNA, and other organelles.) The presence of these inner structures allowed for enhanced complexity in cellular functions. Only then could multi-cellular organisms start to arise, such as plants and animals, including human beings.

If this once in Earth history merger had not happened, or not happened to the particular pair of cells that are your (and all of our) ancestors, you would not be here. In other words, if two other cells had instead done the same “once in history” trick at a different place and time, but not our two at their place and time, you would likely be no beneficiary of the resulting causal stream. None of us would. You are built of eukaryotes stemming from that original pair.

CELLS + CELLS

If you look in the mirror, you should notice one thing quickly: You are not a single cell being. Rather, you are a collection of trillions of cells working in harmony.

Thus, fortunately for you, about 600 million to 1 billion years ago, the first multicellular life took hold. That was some 3 billion years after earliest life on Earth, so no hurried event.

The transition to multicellular bodies likely began when various eukaryotic cells clumped together in sticky groups. Cells in these groups might begin to specialize in specific functions, leading to symbiotic relationships among the cells.

Many of the specialized functions that began to appear then still appear within you, sustaining your life.

For example, in plants and animals, including in you, some cells began to specialize in providing bodily structure and support. They varied in strength and softness, rigidity and flexibility, suited to specialized functions. In the human body today, your hard bones and more malleable cartilages result from similar specialization, lacking which you’d be reduced to a disjointed lump on the floor.

Other cells began to offer protection to their cluster, and to construct barriers between functional sections and the outer world. Today, your skin’s epithelial cells form the outer covering of your handsome body, and also line and protect your inner organs and internal cavities. This shields you from injury as well as from microbial infections, while holding liquid internally to prevent your insides from running dry. Epithelial cells also evolved abilities to aid in the absorption of nutrients by the organs and glands which they surround, as well as to mediate the secretion of hormones and enzymes from those glands. In your kidneys, they participate in transport and filtration. Employing hairlike cilia and microvilli, which greatly increase surface area, others clear the respiratory tract and aid in the absorption of nutrients in the intestines. In more complex bodies, some epithelial cells manifested sensory abilities, such as in your taste buds and the olfactory cells of the inner nose. Other sensory cells became photoreceptors, descendants of early cells exhibiting a most primitive light-sensitivity, today allowing for vision as our eyes. Still other epithelial cells evolved to exhibit usefulness in energy storage, such as the fat cells (although many of us have too many of those.)

Some cells began to specialize in communication between bodily systems. Examples which first appeared in your much simpler ancestors include nerve cells for electro-chemical signaling in response to stimulation, allowing sensation, basic movement and coordinated function. Some eventually became the neurons of the brain. Hormone producing cells also allow further chemical signaling which regulates metabolism. Contractile cells give movement and power, such as in your heart, limbs and other muscles. Immune cells stand as soldiers ever defending against viruses, bacteria and other pathogens, while assisting in damage repair. Some cells, the stem cells, even evolved to remain undifferentiated until called to specialize for bodily development or injury repair.

Of course, all such functions are important, and most are indispensable, to your every moment of your life today.

Gradually, a certain fuzziness appeared as to whether “clumps” of cooperating cells, consisting of a colony of varied residents, had become a single body with diverse organs. However, this transition to specialized, multi-cellular, cooperative bodies allowed organisms to grow larger in size, and ever more complex.

Even reproduction became a matter for specialists: While most cells will divide on their own, with time, certain specialized cells appeared dedicated to the reproduction of the unified organism as a whole. In animals like us, these are the gametes of sperm and egg, each with half of the host creature’s genetic code. The complexity of the parents, with minor mutations, thus is passed down and become the complexity of the child, passing the patterns of specialization and interrelationship into the next generation.

Communities had become united bodies, functioning with internal harmony. As evolution continued, the next step would the amazing diversification of individual life forms on Earth.

CRYOGENIAN AND CAMBRIAN

Our human existence today depends on both those who survived, and those who did not. Early Earth was not a place for individuals and whole species unable to adapt. Some went on to live, breed and thrive, while most species and individuals flopped. Radical climate changes reset the planet’s populations from time to time, picking winners and losers. Of course, you are one of the winners, as was every single one of your ancestors back to the simplest cells. The prize has been your personal birth.

However, let us never forget that our victory as survivors stands on mountains of those who lost their lives, or who never had a chance to live at all.

It is hypothesized, for example, that during certain eras of the distant past, this planet experienced extreme glaciation. Most, and possibly all, of Earth’s surface was once covered by ice, including the oceans. This Cryogenian Period is believed to have occurred approximately 720 to 635 million years ago, with freezes lasting for millions of years each time. The triggers may have been an extreme reduction in CO₂ and other greenhouse gases in the atmosphere, or a reduction in the planet’s volcanic activity, both for reasons that are not totally clear. Possibly there were changes in the Earth’s orbit of the Sun, or in the configuration of the continents which changed ocean currents and reduced heat transport between the equator and the poles. Once the planet was well covered by ice, a mirror effect reduced the globe’s ability to absorb sunlight, further increasing cooling in a positive feedback loop.

Whatever the cause, the effect on then existing life forms would have been dramatic. Some life was able to survive in local pockets, such as near hydrothermal vents where water remained liquid, with the heat and ejected materials supplying energy and nutrients. Those less fortunate, unable to adapt to changed conditions, were wiped from the world. Obviously, our ancestors were among those able to adapt. As well, it is thought by some that the strains and demands of these extremely harsh conditions created selection pressures that stimulated radical adaptation and innovation which, quite literally, would explode across the face of the Earth in the more hospitable period which followed.

In other words, when the going got tough, the tough got going … and diversifying.

Eventually, the glaciation periods ended for reasons as mysterious as their start. Greenhouse gases and volcanic activity increased again, warming the planet. Life bloomed.

It is widely believed that, just before and during the icy eras, life on Earth was still extremely simple and uniform, perhaps just a few species of single and eukaryotic cells. Some scientists think that there was a bit more diversity than that, including various ancestors of amoebae, fungi, animals and plants. Still, it was not anything like what was about to follow.

About 100 million years after the Cryogenian, give or take some 500 million years ago, during the Cambrian period, a rapid diversification of life forms occurred. During a short span of only 20 to 25 million years, there appeared most of the major animal phyla. With incredible rapidity (by Earth standards), complex body plans became common, with specialized tissues and distinct body structures including eyes, exoskeletons, and intricate digestive, neurological and reproductive systems.

Accordingly, much of what is now “you” arose in this period.

Look in the mirror again, and you will see a human body with a distinct right and left side, nearly mirror images of each other. We have paired eyes, ears, arms and legs and many (not all) of our internal organs as twin reflections. It is thought that this significant evolutionary step of bilateral symmetry allows for more complex body structures with the efficiency of duplication, facilitating a single head and centralized nervous and sensory system to link it all. This parallel structure, from dual eyes and ears which allow stereo sight and hearing, to paired legs and arms which permit balanced walking and dexterity, are central to our human identity.

Many of us function in life quite well and successfully without one or both eyes, or lacking hands and legs or a kidney.

However, start doing without much more than that, and any human life is doubtful.

We also benefit from a segmented body plan, another innovation of the Cambrian, allowing a human body today that is made of uniquely structured and functioning units and pieces. We also see the early appearance of chordate predecessors to the spinal cord and vertebrae of the spine, together with the centralization of nerves leading to sophisticated central nervous systems that grew in complexity as body plans evolved to grow in complexity. Nerve cells which gathered at the “head” end of early creatures eventually matured into a true brain attached to the spinal cord. Eyes and other sensory structures, for taste, smell and hearing, appeared in simple forms in some of the earliest Cambrian animals, such as trilobites. Although it has been shown that eyes and several other sense organs developed independently, multiple times in many branches of the animal world, they became increasing complex in later vertebrates, including in our own ancestors. Today, your human eyes, capable of color vision, plus three-dimensional sight in high resolution, are the descendants of simple light-sensitive cells and organelles in early Cambrian creatures. The inner ear, allowing both hearing and balance, also has its roots in this period, evolved from early jaw structures.

Both muscles and appendages moved by muscles appeared in the Cambrian period. As you flip through the pages of this book, you are benefitting from that now. Get yourself a snack and make good use of a sophisticated digestive track, running from mouth to anus, passages first seen during this age. Complex closed circulatory systems, internal skeletons and even true sexual reproduction, all sprung forth from the Cambrian. We can thank the Cambrian for sex.

We also see in the fossil record of this period the first evidence of true predation, hunting and killing. We still kill (alas) and consume other life to fuel our own. Such violence and competition then set off an evolutionary "arms race" of predators vs prey, with adaptions appearing one after another to allow hunters to better pursue, and prey to defend against pursuers. The Cambrian soon saw animals with great jaws and sharp teeth, sophisticated digestive tracks, appendages specialized for speed and gripping, and sensitive sensory and nervous systems, each and all ready to fight or run in flight.

Slowly with the passing ages, as nature experiments, some innovations remain and some not. By 400 to 500 million years ago, our piscine progenitors swam in the oceans, possessing fishy genes many of which (not all) are still within us humans today. Then, about 375 million years ago, a fish-becoming-amphibian crawled onto dry ground, perhaps hesitant at first, slowly transitioning by generation, with lungs and leg-fins allowing life both in water and on land. Edible greenery already covered the then two major continents, available as a ready food source. Some creatures thus stayed on shore, returning to the seas less and less as the generations passed. The age of reptiles then began, roughly 360 million years ago.

Time takes its time, as millions and millions of more years pass.

Most crucial for us, 200 million years or so ago, proto-mammals evolved from a biological link, the synapsids, a reptile manifesting mammal-like aspects of skeleton and gate. We are the children of these creatures, tiny at first, with fur and milk and (most importantly for events to come) a self-regulating temperature.

For, as every school child knows, the reign of the dinosaurs ended with a great meteor’s fall some 66 million years ago. In the long winter which followed, our warm blooded line survived and thrived. Many others, less fortunate, did not.

Perhaps no other event symbolizes more clearly the fortuities upon which our current lives rest. We owe our lives today to what was for others a deadly calamity.

THE METEOR AND THE MAMMALS

Most evidence suggests it was a massive asteroid, largely composed of rock and metals. It was far from the largest object ever to strike this world, at a mere 6 to 9 miles (10 to 15 kilometers) in diameter. Still, it is thought, its impact at the Yucatán and Gulf rendered three out of four of the planet’s species extinct.

Several theories exist about the giant’s origins, how it was slowly pulled toward Earth. It likely existed from the earliest era of our solar system, a crumb left over from the formation of the planets, a straggler tumbling in the void. It was certainly itself the product of chance impacts with other objects, time and again, in the great billiard parlor of space. It sometimes took in pieces of others it encountered, and other times crashed and split. Most such bodies can be found in the great asteroid belt between Mars and Jupiter, circling the Sun in various, often wild orbits. Almost all stay far away from here, pose no threat. Sometimes, however, there are exceptions that truly change the game.

What eventually sent the beast our way is far from clear. The immense pull of Jupiter’s gravity can slingshot objects from the asteroid belt, exerting a strong yet subtle influence that sends projectiles hurling gradually toward the inner system. Or, some suggest, an abrupt collision with another large object can cause a fateful turn, like a kid’s game of bouncing marbles. Whatever the scenario, the disruption would have happened millions of years before eventual impact into our world. The meteor likely first spent ages in elliptical orbit around the Sun, sometimes crossing the course of our Earth and the other inner planets, but always (until the fateful day) passing safely by. The Sun, the other planets and our own gravitational nudges must have sometimes pushed and pulled the time bomb ever so slightly, nudging this way and that, in its millions of years of travels, as likely did additional small impacts with other like bodies. By such influences, its course was lightly prodded here and there.

But then, the cumulative effect of these chance happenings eventually lined up our world in its course … and it was now just a matter of time.

Thus was our fate determined by tumbling dice in space.

As it approached Earth, and especially in its ultimate pass, this planet’s gravitational grip became strong, crossing the point where Earth’s attraction exceeded the influence of the Sun, accelerating the great mass and pulling it toward Earth’s atmosphere. Velocity increased, finally approaching 20 kilometers (12 miles) per second near the moment of impact. At such speeds, the air in front of the incoming visitor was rapidly compressed, the effect generating intense friction and heat reaching several thousands of degrees. Smaller objects will burn up completely in such conditions, but for a meteor this large, only its outermost layers would be vaporized. The amount that remained determined what followed.

On contact, the energy released may have been equivalent to 10 billion Hiroshima A-bombs exploding at once. Walls of sonic waves spread out, as the force of collision instantaneously vaporized the meteor itself and a large swath of the Earth’s surrounding crust. The resulting crater today measures some 150 kilometers (93 miles) in diameter, 20 kilometers (12 miles) deep. Mega-tsunamis radiated outward, moving at incredible speeds for thousands of kilometers, flooding coasts until well inland. Billions of tons of molten rock and debris instantaneously hurdled high into the atmosphere, traveling far and wide, then themselves superheated in their own return falls. Massive wildfires resulted around the globe as fire fell from the sky. Other debris remained in the atmosphere, there blocking most sunlight, causing temperatures to fall and photosynthesis to nearly cease. Winter thus covered the planet, lasting months or years. Cold, starvation and biting acid rain were the result, changing the nature of land and sea as worldwide ecosystems were disrupted or collapsed.

Some swimming and flying life made it, others did not. The situation was too much for many large and hungry land animals, especially the cold blooded. On the other hand, smaller animals, especially if warm blooded, could burrow or hide away. Some early mammals were among the survivors. Not all of the either, for the event eliminated many mammals too, with primarily small, adaptable mammals surviving. Survivors included early placental mammals that are the direct ancestors of primates, thus of us.

Your ancestors made it.

Sadly, what was very good fortune for your ancestors was not so for all. Victims included not only those who died in these events, but all their prospective descendants thus denied a chance ever to live. Many species died out, vanished from history, while our bloodline carried on. The events of this world can be truly cold blooded, filled with perilous crossroads of life and death, mercilessly cruel to some but forgiving to others, cleanly dividing winners and losers in the battle to endure. Individuals, whole herds and entire populations are filtered between weak and strong, hunters and hunted, slayers and slain, genetic successes and wiped out failures, those in the right place at the right time and those not. Nature gives and takes away, sorts and separates with harsh and heartless abandon. Our personal existence today rests on the bones and burned ashes of countless others.

I never wish to imply in this book that the amazing road which led to your living today, dear reader, was always a peaceful one for all. Fate is soon fatal to everyone. (We will return to the philosophical implications of that fact in a later chapter.)

But as the planet warmed again following the great calamity, the momentarily unbalanced ecosystems found their equilibrium again.

The age of the mammals, our age, had begun.

CHEMISTRY LESSON

The changes occurring to animal life that today allow your life were not a matter merely of external appearances. Evolution reached right down to our fundamental chemistry.

The hydrogen, carbon, nitrogen and oxygen, calcium, phosphorus, chlorine, sulphur, sodium, magnesium, iodine and iron, and other trace elements, produced an amazing diversity of natural chemicals upon which all our lives rest. These elements came to combine through natural selection into each and all of the biomolecule compounds now found on Earth, each with highly specialized properties sustaining of life. The results, gradually appearing as evolution moved along, were scores of diverse substances crucial to the bodies of all known forms of life, with our lives among them. Those molecules are now our flesh, our blood, the chemistry of each cell, the very nucleic acids and amino acids that give us form.

Given our common ancestry, that chemistry was such as to lead to all other of Earth’s creatures too, for all life on this world shares in our most fundamental features and make-up. There are no biochemicals on Earth that are entirely unique to Homo sapiens, and our DNA, amino acids, proteins, enzymes and neurotransmitters are shared with most other animals, especially our fellow primates.

What is unique in us, however, is that those biochemicals were able to combine in varied structures and concentrations resulting in functions and traits exclusive to humans. For example, while dopamine and other neurotransmitters like serotonin and oxytocin are far from unique to human beings, we humans have evolved more complex and unique dopaminergic pathways associated with higher-order thinking, social interactions, planning and other behavior. Looking in the mirror, we can thus be confident that those chemicals are what allow us the traits that cause us to be human, and to act like humans act.

It is truly nature’s pharmacy.

Here are but some of the biomolecules that evolved over time and which now support our lives. Most are vital to us, quite literally, as we could not live long in their absence. Some have multiple roles beyond those stated, some are components or ingredients of others.

Biomolecules are typically combinations of carbon and hydrogen, with nitrogen, oxygen, phosphorus and sulfur tossed in. The other bio-elements, though much less common, can play vital roles too. All derived, through time, from life’s earliest and simplest chemical beginnings.

It is an apothecary’s cabinet that sustains us, and is us.

A sampling would include …

Acetylcholine(neurotransmitter with role in muscle contraction); Adenine (nucleobase of DNA and RNA); Adenosine diphosphate (ADP) Adenosine monophosphate (AMP) and Adenosine triphosphate (ATP)(ADP, AMP and ADP engage in a complex series of conversions related to RNA and energy storage-transfer within cells); Adenylate cyclase(enzyme catalyzing the conversion of ATP); Adrenaline (neurotransmitter regulating activity in target tissues such as brain and muscle cells, and playing a central role in the survival response to threatening conditions); Adrenocorticotropic hormone(ACTH - stimulates adrenal gland and promotes the synthesis of corticosteroids); Alanine (one of the most common amino acids found in proteins); Albumin (essential for maintaining oncotic pressure required in proper distribution of fluids between intravascular compartments and tissues, and waste product disposal); Aldosterone (assists in regulation of the body's electrolyte balance); Angiotensinogen (peptides aiding in maintenance of blood volume and pressure); Amylase(ingredient of pancreatic juice and saliva employed in breakdown of carbohydrates); Antidiuretic hormone(ADH - produced by hypothalamus and stored in the posterior part of the pituitary gland, acts on the kidneys to concentrate the urine); Arginine(common amino acid, with role in cell division, the healing tissues, removing ammonia waste, immune function, and hormone release); Ascorbic acid (vitamin C – various claimed functions; deficiency can result in scurvy); Asparagine(amino acid); Aspartic acid(amino acid and neurotransmitter that may aid resistance to fatigue); Atrial-natriuretic peptide(ANP - homeostatic regulation of body water and sodium); Bilirubin(waste product formed as red blood cells die and hemoglobin is broken down; managed by liver); Biotin (Vitamin H - crucial in the catalyzing of key metabolic reactions); Calciferol(Vitamin D - contributes to maintaining normal levels of calcium and phosphorus in the bloodstream); Calcitonin (hormone active in calcium and phosphorus metabolism); Calmodulin (involved in signal transmission controlling many biochemical processes by cells); Carnitine(amino acid; transport of fatty acids into mitochondria); Caspase (essential in cell development and the immune system); Cholecystokinin (CCK - peptide hormone in the gastrointestinal system stimulating fat and protein digestion by causing release of digestive enzymes and bile); Cholesterol(in proper quantities, key component of cell membranes providing stability; aid in the synthesis of vitamin D and various steroid hormones; may have role for brain synapses as well as immune system); Choline(functions in structural integrity and signaling for cell membranes, and metabolism of other substances in the body); Chondroitin sulfate(cartilage component that contributes to elasticity of the bone); Cobalamin (Vitamin B12 - needed for nerve cells; hemoglobin production in red blood cells; and in manufacture of DNA); Coenzyme Q(found in cell membranes as an important part of energy transfer); Collagen (main protein of connective tissue such as ligaments and tendons; filler of the cornea of the eye); Corticosteroids(steroid hormones produced in the adrenal cortex, active in a wide range of functions including stress response, immune response, carbohydrate and protein usage, and maintenance of blood electrolyte levels); Creatine(organic acid aiding in energy supply to muscle cells); Crystallin (structural protein in the lens of the eye resulting in its the transparency); Cytochromes(proteins bound to cellular membranes carrying out energy production); Cytokine(protein molecules serving in communication among immune system cells, and between those cells and other type cells); Cytosine(key component storing and transmitting genetic information within DNA and RNA); Deoxycholic acid(one of the main acids produced by the liver, used in the digestion of fats); Deoxyribose nucleic acid(DNA); Dopamine (neurotransmitter and neurohormone, critical to the brain’s control of bodily movements, information processing, and pleasure sensations); Erythropoietin(EPO - growth factor aiding to increase quantity of red blood cells); Essential fatty acids (fatty acids required in human diet for growth);. Estradiol(major estrogen hormone in humans, vital to sexual functioning and also bone growth); Fibrin(protein involved in blood clotting); Fibronectin(important in wound healing); Folic acid(Vitamin M – important in fetal development); Follicle stimulating hormone(FSH – key role in ovulation and conception); Gamma globulin(a class of proteins in the blood including antibodies); Gamma-aminobutyric acid (GABA – neurotransmitter in the brain and spinal cord); Gastrin(hormone stimulating gastric acid secretion for digestion); Glucagon(amino acid functioning as vital hormone for carbohydrate metabolism); Glucose(most important carbohydrates as energy source); Glucose oxidase(enzyme in sugar breakdown); Glutamic acid (amino acid crucial to proper cell function); Glutamine(amino acid important in proteins; also in nitrogen cycle on which humans depend); Glutathione(important in liver function and detoxification); Glycine(amino acid and neurotransmitter in central nervous system, including spinal cord); Glycogen(main storage form of glucose in animal cells, especially in skeletal muscles); Glycolipid(lipid wit role in energy production and as cellular recognition markers); Gonadotropin-releasing hormone (GnRH – hormone in sexual function and reproduction); Granzyme(role in immune function); Growth hormone(important in growth and cell reproduction); Growth hormone-releasing hormone (GHRH - hormone released by hypothalamus stimulating growth hormone release); GTPase(group of enzymes with roles in human sense function, protein biosynthesis, cell division and intra-cell transport); Guanine(principle component of DNA and RNA); Guanosine (crucial to RNA synthesis and protein synthesis); Haptoglobin (proteins in the blood binding excess iron); Heme(vital to oxygen transport in hemoglobin); Hemoglobin(iron-containing oxygen transport mechanism in red blood cells); High density lipoprotein (HDL – cholesterol removal); Histamine(works in immune responses and as neurotransmitter); Histidine (amino acid important to various proteins and enzymes); Histones (proteins important to gene regulation and DNA structure); HLA antigen(recognizes foreign cells in immune system); Human chorionic gonadotrophin(HCG – produced during pregnancy for embryo protection); Inosine (Important in RNA function); Inositol(various functions within cell); Insulin(various functions including regulation of carbohydrate metabolism and related cell chemistry); Insulin-like growth factor (Forms have impact on cell growth and development of nearly every cell in the body, including muscle, bone, liver, kidney, nerves, skin, brains and lungs); Integrin(positioning and communication among cells); Interferon(cytokine protein actor of immune system); Isoleucine(essential amino acid); Keratin(component of skin structure); Kinase (group of enzyments influential in many areas including signal transmition and control of processes in cells, and other biochemical reactions of the metabolism); Lactase(enzyme in lactose digestion); Lactic acid (role in energy production cycle in muscles); Leptin(possible role in metabolism regulation); Leucine(most common amino acid in proteins; important in human growth); Lipase(groups of enzymes connected to lipid use throughout the body); Lipid (fats and related substances required throughout the body); Luteinizing hormone (LH – role in reproduction cycle); Lysine(important amino acid); Lysozyme (enzyme in immune function); Melatonin (hormone regulating metabolic cycles); Metallothionein(proteins that metabolize and regulate metals in the body, such as zinc); Methionine (amino acid important to synthesis of many bodily substances); Myoglobin(vital to oxygen use in cells); Naphthoquinone (Vitamin K – blood coagulation); Niacin (Vitamin B3 - essential to energy metabolism in cells); Norepinephrine(hormone and neurotransmitter in stress response); Orexins (hormones involved in metabolism regulation); Ornithine (amino acid important in metabolic processes); Oxytocin (hormone in birth); Pantothenic acid (Vitamin B5 – required to break down carbohydrates, fats and proteins); Parathyroid hormone (PTH – balances calcium and other aspects of blood chemistry); Pepsin(protein digestion); Phenethylamine (neurotransmitter); Phenylalanine (essential amino acid); Phosphagen (energy storage in muscles); Phenylalanine(amino acid forming other vital bodily substances, such as adrenaline); Progesterone(hormone of fertility and reproduction); Prolactin (PRL – hormone of multiple functions, including milk production in mammary glands); Proline(amino acid in protein production); Protease(enzymes breaking peptide bonds of proteins in various physiological reactions including food digestion); Pyridoxine and Pyridoxamine(Vitamin B6 – vital to amino acid metabolism and energy release); Pyruvic acid(energy release); Renin (enzyme regulating blood pressure); Retinol(Vitamin A – influential in vision and bone growth); Riboflavin (Vitamin B2 – among others, creation of red blood cells and antibodies, respiration, bodily growth, reproduction and thyroid function); Ribose (component of RNA and other substances vital to metabolism); Ribonucleic acid(RNA – amazing mechanism whose main functions include copying genetic code from DNA and translating into protein structures); Secretin(hormone regulating acid production in the stomach); Selenocysteine (amino acid vital to the structure of several enzymes); Serine (important amino acid); Serotonin(neurotransmitter with important roles in the central nervous system and gastrointestinal system); Somatostatin (hormone with important inhibitory functions, including limiting release of growth hormone, thyroid stimulating hormone, gastrin, cholecystokinin, secretin, insulin and other substances of the body); Taurine(chemical in bile which aids in absorbtion of lipids); Testosterone(principal male sex hormone, but present in both males and females, with vital roles in sexual identity and reproduction, body growth, immune function, among others); Thiamine(Vitamin B1 – important to nutrition; deficiency can result in beri-beri); Threonine(essential amino acid); Thrombopoietin(hormone important to the production of blood platelets); Thymine(nucleobase found in DNA); Thyroid-stimulating hormone(TSH - hormone secreted by pituitary gland which regulating thyroid gland); Thyrotropin-releasing hormone(TRH - hormone stimulating release of TSH); Thyroxine(T4 – with Triiodothyronine T3, important hormones produced by the thyroid gland, acting to stimulate metabolic rate, protein synthesis and in the synthesis is iodine, among other functions); Tocopherol(Vitamin E – important antioxidant); Trypsin (enzyme in digestion); Tryptophan (amino acid vital to the structure of serotonin and melatonin, among other substances); Tyrosine(amino acid vital to the structure of thyroxine, among other substances); Ubiquitin (protein involved in marking and removing other damaged proteins from the cell); Uracil(nucleobase of RNA); Uric acid(waste product of nitrogen metabolism); Valine(amino acid) … and more …

I do not doubt in any way that each and all of these substances emerged through natural selection driven by trial and error, natural experimentation engaged in through huge numbers of chemical reactions on Earth over great expanses of time … for that is precisely what appears to have happened. Slowly, over time, each evolved because it added something to the survival potential of those life forms that possessed it.

However, we should again feel wonder and gratitude that what came forth through selection was a specific conglomeration of all of the necessary compounds to enable our lives, not one substance missing if irreplaceable to life, each substance with the particular and unique attributes that, in combination with all the other biomolecules of the body and brain, allow us to feel that wonder and gratitude. We should celebrate the fact that the basic elements present on our planet at the start, so long ago, already had within them the potential to allow each and all of these substances to emergence with their individual characteristics, making possible our emergence, thus letting us celebrate the fact today.

But I jump the gun (a premature release of acetylcholine, perhaps). We first need to ponder (employing glutamate and other neurotransmitters for pondering) the countless twists and turns which came next.

Our lives, yours and mine, are still far down the road. Much has yet to happen before our appearance on the scene.

TAKING STOCK

Before we move on, however, I would like to take stock of where’ve come so far, and recall the central point of my argument.

In the pages that follow, we will continue to see our human body form gradually manifest, recognizable more and more clearly in our ancestral species. Various mutations and changes in body and brain appeared over millions of years, increment by increment, and those which tended to facilitate survival were apt to remain. However, none of that unavoidably requires nature to have had human beings specifically in mind in doing so (let alone you in mind, dear reader, or anything in mind.) In fact, all adaptations are responses to the conditions at the time, not the future (e.g., a new foot structure randomly appears in an individual’s genetic make-up which aids survival during their lifetime, and thus increases the likelihood of its being passed on to the individual's children. According to our present understanding of evolution, the new foot structure does not somehow manifest with future generations and their future survival in mind. In fact, we typically assume that it is a blind process, with nothing “in mind.”)

Nevertheless, the same puzzling truth presents itself again and again:

It remains the case that you, dear reader, were once outrageously unlikely to be you, here and now reflecting back, unless each and all of the myriad mutations in your particular ancestral line had manifested with the specific content, sequence and timing they did through billions of generations, never a miss, sculpting you from head to toe. A failure to appear, or appearance somewhat otherwise, or appearance in a different familial line, or appearance in a different generation, different brood or even different individual could be expected to have set genetic and historical events off in a very different direction ... one away from eventual you. Had a needed mutation not appeared in an ancestor, had the ancestor not passed on the trait in the right generation with the right partner in the right mating which united the right two gametes at just the right moment … and had this not repeated flawlessly since the very first generation when mating began throughout your line of ancestors (not event to mention the ever-flawless splitting and seeding by your ancestors anterior to those) … you would not be you, and seemingly, would not be anything at all.

Is it possible that these two truths might be true at once?

Is it possible that an as yet unknown mechanism might exist to explain the outcome amid the seemingly chance events that are at the heart of natural selection? I believe so.

After all, there are plentiful examples in our world, including within nature:

Migrating birds and fish cross great distances, stopping here and there amid changing weather, crossing great seas without a landmark in sight, enduring surprise obstacles and chance encounters along the way, yet they hone in on very specific breeding grounds. Seeds scatter wildly in the wind, landing here and there, only some finding fertile soil, yet a particular seed so landing will give birth to its particular tree. A seemingly random meeting of sperm and egg begins a process not so random, with a baby of 5 fingers, 2 arms and 2 legs, 1 nose, 1 heart and 1 brain the expected outcome at the other end (generally not a child with any combination or absence of those things.[12]) In all these examples ... animal migrations and returns, scattering seeds, gestating babies ... nature has found mechanisms to convert highly random events into processes less than completely random, with certain outcomes more-or-less fixed and highly predictable. However, these phenomena appeared as mysteries to ancient peoples who lacked understanding of their causes … until our scientists came to decipher the ability of some migrating creatures to follow the Earth's magnetism with the seasons, the biology of seeds, the structures of DNA and RNA. In all such cases, what first appeared largely random, or miracle, magic or act of the gods, proved to have a graspable cause.

Could an as yet unknown selection mechanism or code or honing sense or choice or seed for ‘you being you’ be the same? Might it be theorized, then tested for?

The jury remains out as to whether there is somehow a teleological directionality to natural selection, a “plan” existing from its outset, e.g., a pull or pressure toward intelligent life as a goal. Certainly, science currently disfavors the notion that nature ever had specifically homo sapiens (let alone you and me) as a target.

Furthermore, evolution seems not always an elegant process:

The changes leading to our present bodies were not necessarily smooth and orderly or all at once. Mutations might happen suddenly, even if after long periods. Or, evolution can happen gradually, with incremental changes very much unlike the final outcome (the human inner ear’s evolution from piscine dental and jaw structure is such an example.) Evolution may sometimes “back-track,” going in reverse for a time as new characteristics vanish again (the return of some mammals to the sea as dolphins and whales is such an example.) Some evolved structures appear functional but very inefficient: The spine seems makeshift and poorly structured by evolution for our being upright, the holdover of its origins in four legged then tree climbing ancestors, as anyone with back pain and postural problems can attest. Also, think about what an engineer might have better designed the next time you swallow wrong because esophagus and windpipe share one opening.

Some changes, otherwise beneficial, may also carry enhanced risks (e.g., a mutation with one benefit which also increases the risk of a certain genetic disease.[13]) Helpful mutations may appear, only for the carrier to die before having a chance to mate and pass them on. Also, like mutations may appear repeatedly in disparate creatures of the same species, or in very different species, such as manifold versions of eyes which have independently evolved many dozens of times with unique structures in species ranging from vertebrates to scallops to flies. Some characteristics, such as our unique human ability to use language, did appear (as you yourself evidence by reading these words), but the timing of the first appearance of that ability could have varied by millions of years.

Nonetheless, despite the craziness and inefficiency, by your very life and abilities, we can be assured that the traits necessary now for you to be you did appear, and with the right timing in the right individuals within your ancestral line to have allowed such outcome, bar none. The wild, complex, spinning gambler’s wheel of mutation and mating somehow spun around … again and again, again and again … through millions and billions of years into the exact outcomes needed for you, trillions of spins after trillions of spins, the silver ball always falling in the correct hole. You are the conclusive evidence.

Can a mechanism exist by which both facts are true at once?

Many an A.I. program, assigned a desired task (e.g., to find a pharmaceutical compound to cure disease X) may attempt a variety of combinations, crazy patterns, hits and misses, misguided solutions and dead ends, before honing in on certain promising or likely directions. From outside, its doing so may appear far from smooth and orderly, with patterns manifesting suddenly, but also sometimes gradually, back-tracking, producing unexpected side-effects, or some less than optimal but adequate ways of doing things, some results that are overlooked at first, or very different compounds that each do much the same thing. Nonetheless, if left running, there is a good chance that the A.I. will eventually arrive at X, even if not in the optimal or most efficient way. To the ignorant observer, unaware of the experiments and varied attempts happening within the black box, and the mathematics behind it, what will be seen is little more than a button pushed at the start, followed by result X that appears to pop up magically at the other end.

Is evolution somehow so? Are we simply in the dark about evolution’s black box?

One thing appears a good assumption: The world might have done just fine without Homo sapiens.

Furthermore, while the advent of Homo sapiens as a species was once ludicrously unlikely, your personal existence among the Homo sapiens was once even so much more ludicrous, given what we know about sex, fertilization and the odds of a particular sperm meeting a particular egg.

Nonetheless, it happened.

Looking at all present, past or prospective “could have evolved but did not” options for alternative life forms that are not our species, let alone you or me, it seems that the Earth might easily have carried on wonderfully without you and me most specifically, our human species generally. You and I, on the other hand, could not have carried on without humankind, for we are human.

Fortunately, it all worked out.

TIME WAITS FOR NO MAN

I am not asserting any impossibility in the evolution of the human body from early mammalian bodies, let alone from the many ancestral species that came before. It would be foolish to do so. Obviously, it happened and, thus, was possible. The fossil record, while filled with large gaps and various ambiguities, is sufficiently complete to show several of the homo, ape and earlier species that bridged the way. Looking in the mirror, we can confirm that we have the human bodies we have, we can visit museums housing the bones of Australopithecus and the earlier Pierolapithecus, we can note the similarities and differences we share. Based on the similarities, we can surmise that our bodies came from there directly, or that we are cousins arising from some common source or mix.

I take no stand in favor of assertions put forward by certain scholars, identified with the so-called “intelligent design” movement, who propose that Darwin’s theory of evolution must be wrong for various reasons. They point to certain bodily systems which, they claim, are “irreducibly complex,” with too many crucial parts in complex relationship to have evolved step-by-step. They assert that small intermediate steps in mutation to their present state would have afforded no evolutionary benefit, thus it is unlikely that such useless or non-functional, sometimes even harmful, mid-way structures would have been passed on to coming generations.

For example, biochemist Michael Behe, in his 1996 book “Darwin's Black Box,”[14] cites the example of bacterial flagellum, a structure which much resembles a rotary motor at first glance. The organ enables certain bacterium to swim by rotating a long filament through a complex interworking of approximately 40 different proteins. This multipart structure is often cited by proponents of irreducible complexity as an example of a structure that could not have evolved through gradual Darwinian evolution.

On the other hand, critics have challenged Behe’s claim by demonstrating that there are plausible intermediate stages in the flagellum’s evolution that would have been functional, provided benefits and thus may have survived to be passed on to subsequent generations.[15] Each small step may provide a small functional advantage, even if not directly related to the final functioning of the system as a whole (in this case, motility).

Closer to my interests, certain mathematical claims are made regarding the unlikelihood, or impossibility, of evolution in general. Some mathematicians and biologists have attempted to demonstrate that there was not sufficient time for evolution to result in us, and that some specific functional developments were extremely unlikely to the point of impossibility. Are they correct?[16]

An example is the following kind of argument, which I feel is mistaken:

Since a gene is a chain of DNA chemical bases, usually noted as G, C, A and T (and assuming that any sequence is as likely as any other) the odds of a gene with, for example, 100 bases containing a particular sequence has a probability of ¼ multiplied by itself 100 times (¼ x ¼ x ¼ x ¼ … ). ¼ x ¼ = 1 in 16, while ¼ x ¼ x ¼ = 1 in 64 and ¼ x ¼ x ¼ x ¼ is 1 in 256. Thus, the odds of the 4 chemicals being found in a particular sequence of 100 bases is
.

1 in 16069380442589902755419620923411626025222029937827 92835301376 times.[17]

Sometimes a similar argument is made with regard to proteins as sequences of amino acids. However, such arguments are likely mistaken: Genes and proteins are not formed like random “1 in 4” dice rolls, because natural selection is a non-random process with random aspects. It keeps winning tosses, passing them on to coming generations, but discards losing tosses, such that the result is not totally random at all.

A somewhat more sophisticated version of this argument by evolution critics is this: Suppose you toss 100 dice with 4 sides all at once, and the result is a specific sequence. (To simplify the example, let us say that the 100 dice all landed on 4.) If we apply this logic to the flagellum, for example, we find that it consists of a collection of individual proteins constructed and working in a specific form, a form that would be extremely improbably to find if by chance. However, according to evolutionary theory, natural selection again serves to select winning from losing combinations. So, if there were many tosses of 100 dice, and “all 4’s” was the winning (surviving) combination, while all other combinations were losing (not aiding survival) and thus discarded by nature (i.e., the creatures with such combinations die without reproducing), then it would be no surprise to find that the survivor has the winning combination even if rare (all 4’s).

It is something like a quiz bowl that starts off with billions of contestants, but eliminates contestants in each round who respond with even one wrong answer in a round. Soon, only a handful of quiz whizzes remain who have gotten only all right answers.

Evolution of complex bodies like our own is not mathematically impossible within the time periods which were available for their evolution. Both the fossil record, and computer modeling, demonstrate that slow and steady win the human race.[18] Evolution works through incremental changes over millions of years that accumulate more rapidly and efficiently than one might think. Because of the large size of populations, a mutation that is effective to improve survival is thus passed on to the next generations. Furthermore, not all mutations need to improve survival in order to be passed on: Genetic drift is the process by which random mutation can be passed on just because the gene carrier is fortunate to breed and survive (e.g., the gene carriers happens to survive a chance flood which killed carriers of other, better genes) The survivor’s genes will be passed on whether or not they aid survival. Within a few generations, such genes and their traits will be found in millions of individuals who are heir to the original carriers. On the other hand, harmful traits, especially if deadly, will tend to be slowly filtered out by selective pressures, for their carriers will typically not to survive and breed.

In many species which breed and give rise to new generations quickly (such as bacteria, insects, and small mammals), change also happens more quickly. Population size is also important for the simple reason that large populations produce more mutations in each generation, which are then all put to the test of survival. This increases the chance that beneficial mutations will arise and spread into future generations.

Chance events can speed evolution. What may appear to be disastrous (and was fatal to some individuals or an entire species) may actually be a boost and kick-start to rapid changes for other species. For example, extreme events such as mass extinctions due to meteors (as we saw with the dinosaurs), volcanoes or floods, plagues in which only some have immunity, climate disasters and the like, can create massive selective pressures for change. An example is the Cambrian Explosion, discussed earlier, which witnessed a rapid and extremely varied diversification of complex life forms within a relatively short time period apparently due to great changes in ocean chemistry and other environmental changes.

Over billions of years, adaptions which are barely noticeable over a few generations will accumulate, and produce large-scale transformations which become conspicuous only over those longer periods. An example is in eye structure. Mathematical models have demonstrated that a simple, light sensitive patch of cells on a creature’s surface can evolve into a complex eye structure in less than half a million generations of incremental improvements.[19] In evolutionary terms, that is not much.

Of course, real evolution involves so many variables, outside factors, seemingly chance happenings, hits and misses, and complex inter-relationships, that the actual process can be quite chaotic. Nonetheless, the basic premise holds: Natural selection is a process by which losing numbers are discarded, while only winners remain, such that an unlikely outcome may not be as unlikely as it seems. In other words, it is a process which shortens the apparently long odds, making unlikely outcomes much more likely or even a sure thing.

Thus, my assertions in this book are a bit different from the “intelligent design” arguments outlined above:

Namely, I point out the radical unlikelihood of the precise sequence of historical events, including the twists and turns of evolution, having led to the reader. It is my belief that there may be a similar “odds shortening” process at work with regard to our personal appearance in space and time despite the odds, a process resembling the odds shortening process of natural selection itself. This process (even if as yet not understood) would help make our existence much more likely (or even a sure thing) rather than just a product of random chance through billions of years.

The question is not whether evolution works to produce effective, complex physiological features which enable life in general, and intelligent life in particular. It is the overwhelming consensus of scientists expert in the field of evolutionary biology that it can, and does.[20] The question is instead whether or not there is something additional to the process which somehow brought together that physiology with this particular writer and most personal (you) reader, both alive and self-aware, despite the once preposterous odds of that eventualizing. The question is not so much whether a complex eye could evolve over half a million generations (it could), but how those eyes ended up as including your particular pair of eyes, assuming the cause was not blind chance.

So, with that in mind, let us now walk the path that rambled from our first fuzzy ancestors to your fuzzy head.

FROM MICE TO MEN

There were mammal-like reptiles long before the age of the dinosaurs. Then, with time, true mammals evolved, scampering between the legs of the dinosaurs who “ruled the planet” by dominating terrestrial ecosystems.

Our mammalian ancestors were small, mostly nocturnal creatures who kept a relatively low profile. However, they had already developed many characteristics on which our lives today depend, beyond merely being warm-blooded and thus able to self-regulate body temperature in a sometimes cold or hot world.

There were also improvements in digestion and sensory systems, a more complex central nervous system, agile locomotion (eventually to become our ability to walk upright), refined muscle action and spatial control, increased oxygen uptake and better blood circulation, responsive blood pressure and bodily chemical regulation, more efficient kidney and liver filtration systems and, of course, continual changes to the brain that, eventually, would result in your ability to read and comprehend these words right now.

Perhaps we could have done without aspects of those changes, and might have gotten by with some different systems and abilities here and there. We even might have done without a few parts completely. An extra eye in the back of our heads might have been useful.[21] Do we really need earlobes, for example, although a nice place for hanging jewelry?[22] However, overall, we have needed, and continue to need, most all evolved bodily structures to be as we are.

Following the great meteor, mammals diversified to occupy many of the ecological niches left vacant by the demise of 75% of all other species. Environmental openings had appeared for new carnivore predators, herbivores and scavengers on land, in the water and the air. The mammals stepped in to fill each such opportunity.

The tiny, early mammals which survived the dinosaurs were likely omnivorous or insectivorous (meaning that you are here today only because some of your ancestors had a yearning for tasty and nutritious bugs, worms and the like.) New food opportunities presented themselves with the new niches, demanding new abilities in food gathering and survival suited to new ecological roles and environments. The process nurtured changes in body size, limb and organ structures. In just a quick few million years, readily identifiable rodents, hoofed mammals and ferocious carnivores could all be found roaming the planet.

For our purposes, most fortunately, among these creatures were the primates. The earliest were likely small, tree-dwelling mammals some 55-65 million years ago. Their line gave rise to all modern primates, including our cousins, the monkeys and apes, … and us.

The changes we witness in early primates are often linked to their tree-dwelling lifestyles. Life up in the canopy and branches required hands and feet capable of grasping, good eyes and other senses, and a complex brain to unite them all in operation. These, in turn, benefitted by other, ever improved bodily systems to sustain, fuel and protect each of those. Our bodies evolved as holistic systems, with each part dependent and benefitting from all other parts, and the whole working to keep the entirety alive.

Let’s begin with what is closest at hand:

A flexible yet firmly clutching hand, with opposable thumb, allowed primates greater manipulation of objects, and finer motor skills overall. The flattened nails of a primate, in place of paws with claws, and increasingly sensitive fingertips with thousands of touch receptors, allowed for precise gripping and careful manipulation of food, simple tools and other objects. Derived from this, our highly dexterous human hands today, with thumbs that can touch each fingertip, provide great precision, both strength and delicacy as needed, and control over movements that can reach the skill of a gifted surgeon, artisan or artist. Good hands are essential for handling tools, especially the later, more refined kinds such as the ink brush or scalpel. Reaching beyond the hand itself, our primate shoulder joints evolved to permit wide ranges of motion in multiple directions. Once providing an advantage in tree-dwelling, this enhanced flexibility let us powerfully and accurately throw objects such as spears for hunting, and to engage in other tasks requiring upper body mobility.

The abilities present in good hands were expanded by the creation of good tools: Early humans began crudely, but developed and benefitted from stone knives, spears, hammers and axes (for hunting and, sadly, for warfare as well.) These tools eased the labor of hunting, gathering and preparation of food, and enabled the building of better shelters and more effective defense. Eventually, more refined tools and increased dexterity allowed for pottery making, wood carpentry and metal working, all critical to human society’s development. Only we humans, among all Earth species, can kiln a pot or forge steel. Agriculture and commerce, craftmanship and art were pushed forward by the thumb and fingers. Picking and planting seeds, harvesting and domesticating animals were all made simpler. With time, farming advancements allowed humans to settle in fixed places, building permanent communities as they transitioned from “hunter-gatherer” nomadic lifestyles to agrarian life in villages, then in large cities. Populations grew with steadier food supplies. Your every ancestor was likely fed and sheltered employing these new skills.

Art, artisanship and higher culture all benefitted from good hands, as the ability to draw, paint, sculpt, assemble and write all require fine motor skills and hand-eye coordination. In turn, better manual abilities led to greater artistic abilities which drove, or went “hand-in-hand,” with increased mental abilities, hu-manifesting talents for greater originality and symbolic thinking and reasoning. Early cave painting, carving, pottery and other abstract making allowed human beings to form and express complex ideas, expand their imaginations and problem solving skills to degrees seen in no other prior or current species. With the development of language and writing, cultural continuity, together with the spread and preservation of innovative knowledge, all became possible. The words on this page, typed by my hands, remain a prime example. History, law, theatre and literature, trade, religious beliefs and science were all indirectly spawn of the dexterous hand and thumb, coupled with our very large brains. With changes in society, culture and language came social bonds, family units, new ways of governance and labor far beyond anything possessed by any other animals. Microscopes and laboratory experiments, the engineering of other precise devices and other object construction all require meticulous hand movements permitting careful measurement, delicate placement and exacting control of materials.

All human structures, from the Great Pyramids to urban skyscrapers, rocket ships to microchips, depend on our unique hands and digits.

Today, that same dexterity permits the manipulation of laser beams, flight controls, keyboards and phone screens. Let’s give a big “thumbs up” and an “okay” sign!

But the hand cannot do any of this on its own: There must be keen senses to guide the hand.

Your handsome face, with its binocular (side by side) eyes, has allowed for improved depth perception and 3-D imagery, important for moving through complex environments such as tree canopies and jungles (or busy city streets for most of us), as well as in spotting and avoiding dangers. We may have lost something with eyes no longer at the sides of the head, but we thereby gained the ability to see what was ahead. Our primate predecessors’ trichromatic color vision let them spot ripe and colorful fruits and young leaves. In your human self, depth perception, binocular and color vision are the basis for hand-eye coordination, spatial awareness, judging and measuring fine movements, recognizing separate objects and their qualities, interpreting visual cues and social signals, identifying friends, loved ones and enemies, and appreciating or making beauty and art.

As the layout of our faces changed, so did its musculature, allowing for more subtle communication by facial expressions: Happiness, sadness, wonder, surprise, disgust, and a wide range of other emotions critical for non-verbal communication, can all be conveyed by the highly expressive human face, sometimes just by raising an eyebrow and curling the lips. Even our closest relatives in the ape family cannot produce facial expressions of such variety. Together with hand and verbal/linguistic communication, the human face facilitated complex social signaling, bringing forth empathy, understanding and connection.

But behind the face is what ties it all together: our magnificent brain.

Ours is not the largest brain of any Earth species. That honor goes to the sperm whale, at 8 kg (18 lb). Elephants also have us beat, and dolphins by a little bit. But our human brain, though only some 1.5 kg (3.3 lb), is nonetheless large relative to our body size, and that makes an important difference. In huge animals, increased size may simply be due to the increased demands of maintaining a large body, rather than increased intelligence. In fact, when mammal brains increased in size between species, not all brain parts increased equally, with a greater fraction of larger brains generally taken up by an increase in the cortex. From early primates to hominids and, with time, to Homo sapiens, cranial capacity (the volume of the interior of the skull) progressively increased. Homo habilis lived with a brain size of some 500-687 cubic centimeters, while Homo erectus reached 600–1250, both small compared to our typical 1400 cm³.[23] [24] Modern chimpanzees have a capacity of 275–500 cm³, and gorillas 340–752 cm³.

It is not clear, however, what direct connections exist between sheer brain size and increases in intelligence and abilities. More than the gross amount of brain tissue, the patterns of its structuring may be more crucial. Some research points to other factors in intelligence, such as the quantity of cortical neurons and the speed of their connections.[25] It seems to be a matter of how the space is allotted, the number of connections, and what it all can do, more than raw size alone.

One thing that is undeniable when comparing man and modern monkey, is that changes in intelligence and capabilities did occur. Arguably, human beings were on the winning side.

Judging from modern primates, changes in brain size and structure compared to earlier mammals allowed for more complex social interactions, increased memory and problem-solving skills. Mice and rats can solve mazes, and monkeys can sometimes pick locks and escape cages. However, only humans can design the maze experiments and build the locks, then write papers on their experiments and debate the significance. Our developed brains, coupled with our opposable thumbs, delicate senses and the other changes, made for a powerful combination.

One unique aspect of human life, and thus your life, is our ability to exhibit complex social behaviors.

The especially large and complex human neocortex permits abstract thinking, linguistic abilities, enhanced planning skills and creativity which can all be shared and participated in as a group. Our early primate ancestors engaged in increasingly complex behaviors that enabled (and sometimes required) collective living which, in turn, demanded social intelligence, better communication skills, group hierarchies, alliances and awareness of kinship. Certainly, complex social structures and aspects of all the rest can be found in ant hills, fish schools and bird flocks. However, nothing resembles the degrees of sophistication found in monkey and ape tribes and, especially, the human society of which you are part. Our human capacities for language, cultural learning and the transfer of knowledge, cooperation, empathy and expression of subtle emotions seem to far exceed all others.

Sadly, we have also kept our propensities for anger and violence.

However, we are, perhaps, the one species with the potential to bring ourselves beyond such dark and destructive propensities.

I hope we do soon.

Some chimpanzees, dogs or cats, dolphins, cows and other mammals evidence that they possess to some degree a conscious sense of their own “self” as personal and separate from other animals and things. On the other hand, it is questionable whether any other species has an inner life, and strong sense of self, with the richness and complexity of Homo sapiens.

Language, for example, is unique to humans, and is a tool for self-reflection which goes beyond simple, barely expressed emotions. It permits us to think about ourselves in at least as many ways as there are adjectives and creative expressions in the dictionary to describe our feelings, interpret our memories and voice our desires. Our ability to name, describe and reflect on our inner world permits a coherent sense of self-awareness, as well as the development of a personal narrative that is at the core of one’s own identity. Are you not hearing the words on this page right now, within you, through some inner dialogue? Do you not engage in an internal monologue that narrates much of your life? Do you not have internal debates and discussions with yourself which evaluate your actions, past histories, future plans and intentions, desires, likes and dislikes, fears and opinions through critical reflection? Language offers a framework for self-reflection, abstract thinking, complex planning as well as emotional understanding and expression, all of which together are central to your personality and personal experience of “your” life as yours.

In other words, you could not have a sense of you being “you” if we humans had not evolved the ability to experience such a complex world between our ears. As a result, the self/other divide is strong in human beings, and we feel ourself clearly distinguishable from other beings and things in the outside world, perhaps to an extent far beyond smaller brained lifeforms. We cannot know what a cat or caterpillar, pig or possum experiences as its inner life, nor its personal sense of “self,” but I suspect that it is more immediate, driven by simple needs, far less complicated than the mental life of people

Other creatures certainly exhibit memory to various degrees, but human beings use language to encode those memories, and have the ability to visually and viscerally relive memories of long ago to a degree mimicking our experience of present life events. The ability to have such a detailed personal history held between one’s ears helps create our sense of being a continuous self over time. We daily tell ourself stories about our “self” that sculpt a multi-faceted but unified concept of being the self who experiences, feels and is at the center of our life, looking out from our own eyes at those events as they transpire.

Language further allows us to engage in the fashioning within of subtle, abstract ideas about the world, each accompanied by adjacent associations and emotions, which become our personal, most intimate notions of love, justice, ethics, meaning and our place in space and time. The result is a sophisticated intellectual life far beyond the much more immediate sensory experiences which narrowly bind (I assume) the inner lives of even the nearest species to our own. Other animals may follow instinct by migrating and mating with the changing seasons, struggling each day just to stay alive, while human beings plan, organize, work for goals, supervise tasks, ponder potential outcomes, employ or kill time and engage in silly amusements to a degree which makes our great cities so much more than simple beehives. We shape the future, now to a degree which launches rockets to the stars and takes even human evolution itself into our control. We human beings create art and architecture, philosophy and legal thinking, science and literature that reflect our individual and communal notions of meaning, beauty, fairness and possibility. That wealthy, interior, intellectual self enjoyed by most of us provides outlets for our curiosity, creativity, expression and introspection. The complex human brain deals in symbols, metaphors, fantastic imaginings, allusions and creative inventions certainly far beyond any other species on this planet.

We ask “big questions” about reality, much as I am doing here.

We can express, understand, discuss and debate differing points of view, while composing love poetry and great comedies or dramas. Our ability to do all these things simultaneously gives rise to our self-notions of what “I believe, I love, I detest, I want, I miss, I sorrow for.” Language thus gives shape to the contours of life, plus the larger cultural and social identity, group values, shared stories and traditions that you use to identify yourself as “yourself,” most of such information learned and incorporated as you matured from child to adult. You gradually shaped your personal values and ethics, notions of right and wrong, in ways that no ape can come close to matching with its simple sense of personal territory, group ranking, and drives to eat, fight and mate. You also feel guilt, fear for imagined futures, regrets for a recalled (and half imagined) past, longing for those who are absent, grief for those who are lost, to degrees no more than hinted at in other mammal species (yes, the elephants have been shown to grieve terribly.) You have a sense of agency, including ethical agency and, hopefully, personality responsibility for your own behaviors.

I do not mean to present an anthropocentric view of what is valuable in this life. All animals (we are animals too) have their place, their talents and beauty. You cannot see at night like a bat, you cannot swim like a whale. I will never say that one species is better or worse, or more special in this world, than any other, for all is interconnected.

We must be thankful, not only for our own direct genetic ancestors, but also for the lives and survival of all the other humans and other animals upon which we depend, together with all the complex eco-systems upon which we all depend.

We are truly all in this together.

Ecologically, our very lives depend on the creatures great and small in the webs of life to which we cling. They sustain us now, and their ancestors made possible the lives of our ancestors then.

Nonetheless, the topic of this book is you, and the rest of us human beings, so I merely wish to highlight what makes you possible in your experience of “you-ness,” and what has been necessary for that.

With all due respect to ant and pigs, they could not write this book … nor, of course, would they feel need to. (Perhaps they have too much innate wisdom and common sense to do so.) But none of them have either the linguistic resources or complexity of thought to do so.

What developments in the human brain allowed homo sapiens to develop such abilities in language and complex thinking far beyond our ape ancestors and earlier mammals?

As the brain evolved from early mammals to ape, then to homo sapiens, we find changes in brain size and neural connectivity, as well as the development and specialization of brain regions associated with abstract thought, memory, social interaction and other regions that enable our uniquely human abilities. Most importantly, the prefrontal cortex, central to executive functions such as planning, complex problem-solving, decision-making, and self-control, expanded dramatically in human beings. The neocortex layer, responsible for integration of sensory data, complex cognitive functions, aspects of language, abstract thinking and social understanding, also blossomed.

Increased neural connectivity resulted in complex neural networks that integrated and facilitated communication and harmonization of disparate regions of the brain. Some believe that this heightened integration is the very source of human consciousness. Furthermore, enhanced synaptic plasticity allowed for the forging of new neural connections based on experience and learning, thus facilitating the retention and use of new information and the learning of language. For the appearance of true language, Broca’s Area, in the left frontal lobe, enables speech production and complex grammar. Wernicke’s Area, in the left temporal lobe, is associated with our comprehension of complex language structures and the formulation of effective and appropriate responses, the basis of communication. In the majority of people, language functions are more heavily sited in the left hemisphere of the brain, with circuits for processing syntax, grammar, and vocabulary to degrees allowing language complexity and comprehension. Our hippocampus plays a key role in these functions too, allowing us to store, retrieve and then process vast amounts of learned information which contributes to the feeling of continuity of self.

If we assume that our sense of self and identity, right now, is dependent on a brain which developed in ways which allow our special human abilities and personal experience of being human, then you should be thankful that it all worked out so. It is highly unlikely that you could have your present sense of being you were one or more of those key functions lacking.

But here is where the mystery again arises:

It would be foolish to argue that the human brain could not have evolved. Obviously, it could … because it did, as shown by the simple fact that you have such a brain (and it seems to work well enough, I assume, for you to feel as you, reading this book, absorbing its ideas and responding to them.)

I merely point out the obvious fact that nature evolved millions of different species in the history of earth-life, most very distant from human brain structure and abilities. Thus, nature seemingly could have stayed with those species alone, or gone off in totally other directions, far away from us. Even if intelligence were a likely outcome of evolutionary advancement with time, why did evolution not head down the trail of the octopus brain, or porpoise brain, or some other potentially smart brain, rather than the human brain? In fact, nature could have stayed put with the brains of cats or rats, birds or bugs. The world seemingly could have done without a brain as developed as ours (not to mention, without your and my human brains specifically.)

After all, that is precisely what the planet did for billions of years before the short span of time which hosts our appearance in this life.

But here we are nonetheless, with these brains thinking about it all.

THE BIG SQUEEZE

To close this chapter, I would like to focus briefly on a few of the episodes in natural history when our ancestors passed through the ringer of wide mass destruction. Natural selection and evolution can explain so much about our evolution, except perhaps with regard to our extreme luck as happenstance super-survivors. No episodes demonstrate that fact as clearly as the several times in world events when most species were wiped out but, apparently (given our current appearance), all our ancestors somehow snuck through.

We are the repeat survivors of narrow bottlenecks among species that squeezed most others out, terrible periods during which populations decreased sharply, sometimes rendering most complex life virtually extinct on this planet.

We have already touched on the freezing slaughter of the Cryogenian Period, about 720 to 635 million years ago, which may have led to the diverse blossoming of species in the Cambrian which followed. In the Late Devonian, around 375 million years ago, a major population reduction suddenly occurred among fish and tetrapods, the generally four-limbed vertebrates that had begun their slow transition to land from sea. The carnage winnowed down the available genetic lines for continued evolution on land.

Then, circa 252 million years ago, in the Permian-Triassic, the so-called “Great Dying” wiped out 90% of all species in the sea, air and on land. This, the most severe known extinction in Earth’s history, created a bottleneck for the few lineages that survived. Fortunately for us, those included a some therapsids, the mammal-like reptiles to which we, and all mammals, owe our existence.

In the Triassic-Jurassic, 201 million years ago, another mass extinction led to the rise of the dinosaurs. However, early mammal species were also pruned through that disaster, with some making it and some not. Then, of course, at 66 million years, came the meteoric fall of the dinosaurs and start of the age of mammals.

After a brief respite, at around 55 to 33 million years ago, the early Paleogene was a period of great climate shifts. Rapid and extreme global warming occurred, leaving as hearty survivors only those early mammals able to adapt to warmer climes and forests. It is here that we see the prevalence of tree-dwelling mammals, including proto-primates with their grasping, climbing hands and ever bigger brains.

At 14 to 7 million years ago, the Miocene cooling led to vanishing forests and expanded grass and open woodlands. Some primate populations adapted to life on the ground rather than the trees, while populations which could not adapt were pushed toward extinction. It is here that we see the divergence of the great apes from other primates. Bipedalism likely appeared at this time.

Further cooling and glacial cycles, in the Pliocene-Pleistocene Transition, around 2–3 million years ago, put pressure on the now arrived hominins to adapt to cold and variable climates, or else perish too. The fight for food and need for ingenuity certainly favored those whose brains could adapt, use tools and formulate survival strategies, each of which benefits from group cooperation and greater social structures.

Bottlenecks happened after the emergence of Homo sapiens too.

It is theorized that, around 74,000 years ago, eruption of the Toba supervolcano, near today’s Indonesia, may have dramatically cooled the Earth leading to widespread famine. The total population of all Homo sapiens on the globe may have been reduced to a mere 1,000 to 10,000 individuals. If so, all modern humans, including you and the other 8 billion of us, would be heirs to those remaining few.

Even in more recent times, from pre-history to eras of known history, plagues, famines, natural disasters and wars shaved the human population from Asia to Africa to Australia, Europe to the Americas. As but one infamous instance, the Black Death of the 14^th century is estimated to have killed 30% to 60% of the European population. Tens of millions more died in Asia and parts of Africa. The population of China may have dropped from 125 million to 90 million in but a few years due to the plague, and likewise for the loss of a third of people in North Africa and the Middle East.[26]

History is often terrible and tragic.

Nonetheless, not one of your ancestors, not in any epoch or generation, was ever victim of a single famine or flood, war or earthquake, plague or pestilence … not one, not ever … without having first lived long enough to sire the next generation of their/your line.

You come from an amazingly resilient lineage of hangers on who deposited you here, in the middle of time and space.

Turning again to biologist Richard Dawkin, he writes:[27]

This is another respect in which we are lucky. The universe is older than a hundred million centuries. Within a comparable time the sun will swell to a red giant and engulf the earth. Every century of hundreds of millions has been in its time, or will be when its time comes, ‘the present century’. … How it feels to me, and I guess to you as well, is that the present moves from the past to the future, like a tiny spotlight, inching its way along a gigantic ruler of time. Everything behind the spotlight is in darkness, the darkness of the dead past. Everything ahead of the spotlight is in the darkness of the unknown future. The odds of your century being the one in the spotlight are the same as the odds that a penny, tossed down at random, will land on a particular ant crawling somewhere along the road from New York to San Francisco. In other words, it is overwhelmingly probable that you are dead.

In spite of these odds, you will notice that you are, as a matter of fact, alive. People whom the spotlight has already passed over, and people whom the spotlight has not reached, are in no position to read a book … What I see as I write is that I am lucky to be alive and so are you.

Is it just luck?

[1] From his book Unweaving the Rainbow
[2] Or, although more doubtful, a specific group of appearances of life on this planet, in a certain combination of places and times, which somehow later merged or bred together to form our earliest ancestors, e.g., various single cell creatures which combined into single new species. Even if so, they obviously would have done so in a way, in combining, which nonetheless resulted in the single ancestral line shared by all known species on Earth.
[3] There exists some evidence that cellular life already existed 3.5 billion years ago, and possibly near the end of the period of heavy asteroid and comet bombardment from 4.0 to 3.9 billion years ago. This would mean that the ancestors of contemporary life emerged fairly quickly on the geological time scale.[CONFIRM DATES]
[4] The 1953 Miller-Urey experiment ... .
[5] Sometimes called “panspermia,” although that hypothesis is actually more sweeping than “exogenesis” in holding that life’s seeds, and even actual lifeforms, are spread throughout the universe. “Exogenesis” is a less radical assertion that life originated elsewhere in the cosmos and came to Earth, making no prediction, unlike “panspermia,” about the commonality of life in the universe. There is yet no strong evidence to either support or disprove either concept, and the harshness of space and problems of space travel would seem to work against the processes. Various physicists including Sir Fred Hoyle and Chandra Wickramasinghe were proponents, however, and argued that lifeforms may still be entering our planet’s atmosphere.
~~~
Did life’s basic compounds get their start “out there,” then arrive here? We know from spectral analyses that organic molecules are abundant in comets and meteorites. Those comets, together with the sun and all the planets, formed of the materials making up the original stellar nebula. However, closer to the Sun, in the relative warmth, rocky materials tend to be prevalent, allowing for asteroids and terrestrial worlds like our Earth. In the outer regions of the nebula, in the extreme cold, most common are icy clusters of rock and dust as comets. What is more, in the hotter regions, volatile materials may evaporate by solar heating. But in colder sections of the system, volatile organic compounds, containing carbon atoms, are more common and trapped in large amounts within comets. Thus, when the new Earth was subjected to intense comet bombardment in its early years, those visitors may have brought vital organic compounds, if not primitive life itself.
[6] Commencing with the Urey-Miller experiment by Stanley L. Miller and Harold C. Urey in 1953.
[7] For example, in the presence of water, hydrolysis of polymers into the monomers they contain would interfere with the survival of those polymers, as would reactions with other substances. As we shall see, some posit that organic molecules had extra-terrestrial stellar or interstellar origin, brought to earth in crashing comets and meteorites.
[8] For example, a molecule with properties causing other molecules to react, thus creating two of the original molecule, might quickly form a rapidly expanding population of itself. Thereupon, the tremendous numbers of copies being made, combined with the primitive nature of the copy mechanism, could have resulted in occaisonal errors and variations – small mutations that could have started a process of natural selection with time. Some deviations might have been better and faster at reproducing, perhaps, or at snatching and employing the component resources needed for its own reproduction. With time, those designs that could replicate better would come to dominate. With further mutation, the cycle would repeat, a form of “chemical evolution.” Eventually, there might appear models able to synthesize internally at least some of the chemicals needed for reproduction, as well as other materials adding functions contributing to survival. This is just one of many competing theories.
[9] There are no biochemicals on Earth that are entirely unique to Homo sapiens, and our DNA, amino acids, proteins, enzymes and neurotransmitters are shared with other animals, especially our fellow primates. What is unique in us, however, is that those biochemicals were able to combine in varied structures and concentrations resulting in functions and traits exclusive to humans. For example, while dopamine and other neurotransmitters like serotonin and oxytocin are far from unique to human beings, we humans have evolved more complex and specifically structured dopaminergic pathways associated with higher-order thinking, social interactions, planning and other behavior.
[10] However, some theories have proposed early organisms may have emerged more than once, leading to multiple trees of life. Because microorganisms of different species sometimes swap genes when in contact, or by the intermediation of infecting viruses, a web of life could exist rather than a single tree. In this way, it is at least possible that life first appeared in separate places which joined in various ways, meaning that theoretically we may have had more than one “first ancestor.” Even if so, the timely origination of each of those separate ancestors, followed by their chance encounters at the specific moments that formed our specific line of ancestors, thereby exchanging DNA in the specific ways which happened to set the groundwork for what later came, still represents quite a bit of good fortune.
[11] There was only one such branch as evidence by the common DNA shared by all known life on Earth today.
[12] We will address birth defects in a coming chapter.
[13] Sickle cell
[14] cite
[15] cite
[16] https://whyevolutionistrue.com/2022/...nst-evolution/ AND https://skepticalinquirer.org/2022/0...-evolutionism/ AND https://www.theguardian.com/science/...y-of-evolution
[17] For examples, have a look at Morris and Parker (1987, 97–100), Roth (1998, 69–70), and Foster (1999) in https://skepticalinquirer.org/2022/0...-evolutionism/
[18] cite
[19] cite
[20] In fact, bodily design is not always ideal, and sometimes seems jury-rigged by nature, or horribly inefficient. An example is the …… Still, it works good enough for most of us.
[21] On the other hand, an extra eye might have taxed energy and neurological resources available to our main forward facing eyes.
[22] The benefits of earlobes are poorly understood, although some scientists theorize some minor roles in temperature regulation or ear protection. They do not appear to play any significant acoustic function in hearing.
[23] Some say neanderthals had larger brains than humans, although this is disputed. Also, neanderthals had larger eyes and bodies relative to their height than modern human, thus large areas of the neanderthal brain were dedicated to visual processing and bodily control, not necessarily intelligence. When such areas are removed from the equation, neanderthal brains may have been 15 to 22% smaller than current human brains. Pearce, Eiluned; Stringer, Chris; Dunbar, R. I. M. (7 May 2013). "New insights into differences in brain organization between Neanderthals and anatomically modern humans". Proceedings of the Royal Society B: Biological Sciences. 280 (1758): 20130168. doi:10.1098/rspb.2013.0168. PMC 3619466. PMID 23486442.
[24] Most increases in mammalian brain size accompany increases in general body size. There are exceptions, however. The advent of modern man, some 100,000 years ago, appears to include a decrease in body size from earlier species, but an increase in brain size.
[25] Roth, G; Dicke, U (May 2005). "Evolution of the brain and intelligence". Trends in Cognitive Sciences. 9 (5): 250–257. doi:10.1016/j.tics.2005.03.005. PMID 15866152. S2CID 14758763.
[26] Some positive points of the Black Plague due to population reduction …
[27] Unweaving the Rainbow: Science, Delusion and the Appetite for Wonder

[FutureBuddha (Hunches XIII)] The Mammals

[FutureBuddha (Hunches XIII)] The Mammals

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