Posts Tagged ‘evolution’

Demise of the dinosaurs

July 28, 2020

I heard a talk by Frank Wind (pronounced as in “gust of” rather than “wind up”), a retired geologist, on the dinosaur extinction.

Frank started by saying Darwin is his patron saint. He also cited a book by journalist Elizabeth Kolbert, The Sixth Extinction (concerning the one currently underway), and a New Yorker article by Douglas Preston, The Day the Dinosaurs Died. That was actually the fifth and (until now) last mass extinction of species on this planet, 66 million years ago (MYA); the first occurred about 440 MYA. The most severe was the Permian Extinction, about 250 MYA, killing over 95% of marine species and 70% of terrestrial ones.

Those early creatures must have really pissed off God. Except, of course, that he created the whole shebang a mere 0.006 MYA. To be exact, in 4004 BCE. On October 2. At 6 PM. That was the calculation of Bishop Ussher, by parsing the Bible’s chronology, in 1650. Which Biblical literalists today still take as gospel. They place Noah’s flood at 2348 BCE, which did for the dinosaurs. But even that theory is a bit problematical, unless you suppose every dinosaur species literally missed the boat. Indeed, Frank showed a cartoon with the ark departing, two dinos standing ashore, one saying to the other, “Oh, crap! was that today?

And the dinosaurs could not have died out much earlier because, of course, death itself was introduced into the world in consequence of Adam’s “sin.” But actually, the Bible has nothing at all to say about dinos, which were not even discovered until the 19th century.

The whole concept of extinction wasn’t really a thing till then, most people (well, Christians) believing life on Earth unchanging. Discovering dinosaur fossils threw them for a loop. And even science at that time was kind of stumped to explain how such a whole big range of creatures could have more or less abruptly vanished from the scene.

Not until recent decades was a good theory offered, by Luis and Walter Alvarez, father-and-son scientists. They ascribed dino extinction to a huge asteroid smashing into the Earth. There is evidence of such impacts happening periodically, in the form of 190 craters. And the Alvarezes pinpointed remains of the gigantic 66-MYA Chicxulub crater in the Yucatan peninsula and coast. They also found much evidence in the geologic record, identifying a distinct boundary between sedimentary layers at just that time, with the in-between layer being notably different, showing a very high iridium content, which could only have come from an extraterrestrial source. Such evidence is found as far away as New Zealand (can’t get much farther), proving how dramatically the planet’s environment was affected. Frank also pointed to  some fossils discovered in the U.S., showing directly how animal life suffered.

His talk included some vivid descriptions of just how catastrophic an asteroid hit that big would have been. Unfortunately I missed that part because the talk was on zoom and my internet connection cut out. But you can fill it in from various disaster movies you’ve seen.

Not all scientists buy this asteroid theory. They don’t deny the impact, but don’t think it alone can account for the extent of the extinction. Pointing instead to a spate of big volcanic eruptions that seem to have occurred shortly before. But they accept that the asteroid didn’t help.

We may miss having dinosaurs around (though we do have birds, which are their descendants). However, Frank pointed out, it was the demise of the dinos that cleared the way for the flourishing of mammals, which in turn led to the evolution of you-know-who. Though some misanthropic cynics would say this was not such a blessing.

Probability, coincidence, and the origin of life

November 30, 2019

The philosopher Epicurus was shown a wall of pictures — told, reverently, they portrayed sailors who, in storms, prayed to the gods and were saved. “But where,” he asked, “are the pictures of those who prayed and drowned?”

He was exposing the mistake of counting hits and ignoring misses. It’s common when evaluating seemingly paranormal, supernatural, or even miraculous occurrences. Like when some acquaintance appears in a dream and then you learn they’ve just died. Was your dream premonitory? But how often do you dream of people who don’t die? As with Epicurus, this frequently applies to religious “miracles” like answered prayers. We count the hits and ignore the many more unanswered prayers.

I usually work with the radio on. How often do you think I’ll write a word while hearing the same word from the radio? (Not common words, of course, like “like” or “of course.”) In fact it happens regularly, every few days. Spooky? Against astronomical odds? For a particular word, like “particular,” the odds would indeed be very small. But the open-ended case of any word matching is far less improbable. Recently it was “Equatorial Guinea!” Similarly, the odds of any two people’s birthdays matching are about one in 365. But how many must there be in a room before two birthdays likely match? Only 23! This surprises most folks — showing we have shaky intuitions regarding probability and coincidence. Most coincidences are not remarkable at all, but expectable, like my frequent radio matches.

So what does all this have to do with the origin of life? I recently began discussing Dawkins’s book, The Blind Watchmaker, and life’s having (almost certainly) begun with a fairly simple molecular structure, naturally occurring, with the characteristic of self-duplication. Dawkins addresses our intuition that that’s exceedingly improbable.

The essence of evolution by natural selection is, again, small incremental steps over eons of time, each making beneficiaries a bit likelier to survive and reproduce. The replicator molecule utilized by all life is DNA,* which maybe can’t be called “simple” — but Dawkins explains that DNA could itself have evolved in steps, from simpler precursors —non-living ones.

Indeed, non-living replication is familiar to us. That’s how crystals form. They grow by repeating a molecular structure over and over. (I’ve illustrated one we own — trillions of molecules creating a geometrical object with perfectly flat sides.) Dawkins writes of certain naturally occurring clays with similar properties, which could plausibly have been a platform for evolving the more elaborate self-replicators that became life.

Maybe this still seems far-fetched to you. But Dawkins elucidates another key insight relevant here.

Our brains evolved (obviously) to navigate the environment we lived in. Our abilities to conceptualize are tailored accordingly, and don’t extend further (which would have been a waste of biological resources). Thus, explains Dawkins, our intuitive grasp of time is grounded in the spectrum of intervals in our everyday experience — from perhaps a second or so at one end to a century or two at the other. But that’s only a tiny part of the full range, which goes from nanoseconds to billions of years. We didn’t need to grasp those. Likewise, our grasp of sizes runs from perhaps a grain of sand to a mountain. Again, a tiny part of the true spectrum, an atom being vastly smaller, the galaxy vastly larger. Those sizes we never needed to imagine — and so we really can’t.

This applies to all very large (or small) numbers. Our intuitions about probability are similarly circumscribed.

If you could hypothetically travel to early Earth, might you witness life beginning — as I’ve explained it? Of course not. Not in a lifetime. The probability seems so small it feels like zero. And accordingly some people just reject the idea.

Suppose it’s so improbable that it would only occur once in a billion years. But it did have a billion years to happen in! Wherein a one-in-a-billion-year event is hardly unlikely.

The odds against winning the lottery are also astronomical. Our human capacity to grasp such probabilities is, again, so limited that many people play the lottery with no clue about the true smallness of their chances. Yet people win the lottery. And I had my “Equatorial Guinea” coincidence.

And what’s the probability that life did not evolve naturally, along general lines I’ve suggested, but was instead somehow deliberately created by a super-intelligent being of unimaginable power — whose existence in the first place nobody can begin to account for?

Surely zero; a childishly absurd idea. As Sherlock Holmes said, once you eliminate the impossible, whatever remains, howsoever improbable, must be the truth. But the Darwinian naturalistic theory of life is not at all improbable or implausible. There’s tons of evidence for it. And even if there weren’t, Dawkins observes, it would still be the only concept capable of explaining life. Not only is it true, it must be true.

* That all living things use the same DNA code makes it virtually certain that all had a common ancestor. Your forebears were not, actually, monkeys; but the ancestors of all humans, and of all monkeys, were fish.

Are humans smarter than (other) animals?

June 27, 2018

Around 1900, “Clever Hans” was a famous German horse with seeming mathematical ability. Asked “what is four times three?” Hans would tap his hoof twelve times. He was usually right even when his owner wasn’t present; and even when given the questions in writing!

Animal intelligence — and consciousness — are age old puzzles to us. French philosopher Rene Descartes saw other animals as, in effect, mechanical contrivances. And even today many see all their behaviors as produced not by intelligent consciousness (like ours) but rather by instinct — pre-installed algorithms that dictate responses to stimuli — like computers running programs.

Clever Hans’s story is recapped in Yuval Noah Harari’s book, Homo Deus. It was eventually proven that Hans knew no math at all. Instead, he was cued to stop tapping his hoof by onlookers’ body language and facial expressions. But, Harari says, that didn’t debunk Hans’s intelligence, it did the opposite. His performance required far more brain power than simple math! You might have memorized 4×3=12 — but could you have gotten the answer the way Hans did?

This points up the difficulty of inferring animal mentation using human yardsticks. Harari explains Hans’s abilities by noting that horses, unequipped for verbal language, communicate instead through body language — so they get pretty good at it. Much better than us.

So if horses are so smart, why aren’t they sitting in the stands at Saratoga while humans run around the track? Well, for one thing, building that sort of facility would have been a lot harder for horses with hooves rather than our dextrous five-fingered hands. Our tool-making capability is a huge factor. And our intelligence, taken as a whole, probably does outstrip that of any other animal. It had to, because early humans faced far more complex survival challenges. Countless other species failed such tests and went extinct. We did not because an evolutionary fluke gave us, just in time, an extreme adaptation in our brains, unlike any other animal’s. Our equivalent of the narwhal’s huge tusk or the giraffe’s neck.

That happened around a couple of hundred thousand years ago. Yet for around 98% of those years, humans achieved little more than mere survival. Only in the last few thousand have we suddenly exploded into a force dominating the Earth as no creature before.

Why that delay? In fact, Harari notes, our stone age ancestors must have been even smarter than people today. After all, their lives were much tougher. One mistake and you’d be dead; your dumb genes would not make it into the next generation.

Harari thinks — I tend to agree — that cooperation proved to be humanity’s killer app. PBS TV’s recent “Civilizations” series illuminates how things really got going with the development of agriculture about 10,000 years ago. Arguably farmers were actually worse off in many ways; and maybe even humanity as a whole for about 9,800 of those years. But agriculture, and the production of food surpluses, did make possible the rise of cities, where people could specialize in particular enterprises, and interact and exchange ideas with large numbers of other people. That eventually paid off spectacularly, in terms of human material well-being, in modern times.

Harari notes that ants and bees too live in large cooperative communities. So why haven’t they developed computers and spaceships? Our super intelligent consciousness also gave us great flexibility to adapt to changing circumstances. Insects have a far more limited repertoire of responses. As Harari writes, “If a hive faces a new threat or a new opportunity, the bees cannot, for example, guillotine the queen and establish a republic.”

The book that changed America: Darwin, Slavery, and God

February 27, 2018


The Book That Changed America is the title of one by Randall Fuller. It’s about Darwin’s On the Origin of Species, looking at its impact particularly in Concord, Massachusetts.

That wasn’t just Anytown, U.S.A. Concord was the center of America’s intellectual ferment. The protagonists in Fuller’s book include Emerson, Thoreau, Hawthorne, Bronson and Louisa May Alcott, Franklin Sanborn, Louis Agassiz, and Asa Gray — all living in or near Concord and interacting with each other and with Darwin’s bombshell book.


It hit Concord almost simultaneously with another bombshell in late 1859: John Brown’s attack on the Harper’s Ferry arsenal and his subsequent execution. Brown was not, as often portrayed, a madman. He considered slavery a great sin that could be undone only through war, which he aimed to start. He was just about a year early.

America was already, of course, hotly divided over slavery, and Harper’s Ferry raised the temperature further. So did Darwin’s book.

How so? The only possible excuse for slavery was the idea of blacks’ racial inferiority. Thus their constant denigration as a degenerate, brutish species. And slavery apologists, being besotted with religion, had to believe God intentionally made blacks separately and enslavement-worthy. Efforts to prove their inferiority litters Nineteenth century science. (See Stephen Jay Gould’s The Mismeasure of Man.)

(Even most abolitionists thought blacks inferior. But they opposed slavery nonetheless because it was cruel and unjust. This applies to every pogrom, genocide, or other ethnically based abuse or exploitation. Even if its victims were lesser, degraded creatures — it’s never true, but even if it were — their mistreatment would still be cruel and unjust. The creatures proven inferior and degraded are the perpetrators.)

Anyhow, the races’ biological separateness continued to be a matter of intense science-oriented debate.* That’s where Darwin came in.

His book prudently refrained from specifically addressing human origins. (Darwin bit that bullet later in The Descent of Man.) Origin discussed living things in general, and all its numerous examples and case studies concerned non-human life. Many at the time imagined humans were something apart from all that. Yet many others were not so deluded, and they realized that if Darwin’s varied finches and so forth were all close cousins, branches of the same tree, obviously then so were whites and blacks. (We now know that blacks came first, and whites descended from them.)

Thus did Origin explode the moral underpinnings of slavery. And Darwin was not just another polemicist with an axe to grind. Not only was his a science book, it was powerfully supported and argued, hence a devastating blow.

Yet still it was disputed. Inevitably, for a book that gored cherished oxen. And slavery was not the only ox. The other was God himself.

Gods have always been the answer for natural and cosmic mysteries people couldn’t otherwise penetrate. That territory used to be huge. But science has progressively answered those mysteries, inexorably shrinking godly territory.

To naive eyes, the world might look designed, the only possible way to explain life’s diversity and complexity. Literature is filled with rhapsodizing on this theme. Though would any intelligent designer have so filled creation with pain and suffering? Calling this a mystery is no answer.

Thoreau had studied nature intensively, and likewise studied Darwin’s book. He got it, completely; it explained so much of what he’d actually observed. Fuller casts Thoreau as holding that the world is indeed filled with magic and mystery — just not the kind religion postulates.

But Darwin greatly demystified life. His theory was a revelation, a revolution. He called it “natural selection” and “descent with modification;” for short, evolution. His book explained it thoroughly and cogently; there’s hardly a word in it that doesn’t still hold up. A stupendous achievement of human intellect.

And once Darwin unveiled it, the idea of evolution was actually obvious. (I recall Richard Milner’s song, wherein other scientists of the time moan, “Why didn’t I think of that?!”) As Thoreau found, evolution instantly made sense of everything observable about the natural world, everything previously so puzzling. The great geneticist Theodosius Dobzhansky put it thusly: “Nothing in biology makes sense except in the light of evolution.”

Yet, to this day, half of Americans reject it. Fuller’s book recaps the opposition to evolution as it played out at its advent, with famed scientist Louis Agassiz in the attack’s vanguard. Its essence remains unchanged. Evolution shrinks God almost to irrelevance. And not just in biology. If life is attributable to natural, not supernatural causes, couldn’t the same be true of the entire cosmos? To Agassiz, all this was something literally unthinkable.** As it is for his modern counterparts.

Likewise that we “come from monkeys” (or even lesser creatures). Some believe that degrades us. But “there is grandeur in this view of life,” connecting us to every other living thing. And our animal antecedents make us all the more remarkable. It’s sublime that a Darwin, descended from apes, could have the insight to see it. All we’ve achieved we’ve done ourselves, with no help from any god.

A reader of Fuller’s book must be struck by how one key mistake — belief in a god — traps you in a carnival house of mirrors, distorting everything about life and the world. Escape it and all becomes clear. This is the main reason why Agassiz and other scientists of the time failed to see what Darwin saw. Religion blinded them. And even when shown the light, they hold tight to their blindfolds. They torture facts, evidence, and logic, struggling to hammer the square peg of their belief into the round hole of reality.

I find it far better to just accept reality.

* Some even argued for different species on the basis (by analogy to mules) that mixed-race people tend to be sterile — simply untrue. Furthermore, the vast genre of argument that race mixing somehow “pollutes” and degrades the quality of the white race likewise contradicts manifest biological fact: mixing different gene pools improves strength and quality. It’s called hybrid vigor.

** Scientist Asa Gray entered the fray on Darwin’s side, but even he was unmoored by God’s banishment, coming up with the fallback idea that evolution is God’s method for managing life’s pageant. And even Darwin himself seemed queasy about a purely mechanistic view of creation.

Why Do Richer People Have Fewer Kids?

September 29, 2014

UnknownThe Economist magazine has discussed the “demographic transition” – as people get richer, they have fewer children. It’s a key reason why Malthus’s famous prediction of population outrunning food supply – as well as latter-day echoes like Paul “Population Bomb” Ehrlich – proved wrong. Population growth has been decelerating; numbers are projected to plateau around mid-century, and fall thereafter. This is largely due to declining poverty; some countries have seen birth rates drop to a fraction of former levels.

But The Economist wonders why richer people have fewer kids, which it labels “biologically bonkers,” because normally animal populations in flush environments reproduce more, not less. Noted are two distinct reproductive strategies: “r-selection,” throwing a lot of offspring at the wall hoping some will stick, versus “k-selection,” having fewer offspring but investing heavily in their success. The latter, The Economist points out, may produce fitter descendants, but not more descendants.  Unknown-2And natural selection (as Richard Dawkins elucidated in The Selfish Gene) targets not quality but quantity, with genes “trying” (not consciously of course) to propagate the most copies of themselves. (It’s simply math: genes that do so become the most common.) That biological logic seems violated by k-selection.

The Economists’s suggested answer is that while today r-selection might produce more gene copies, because most offspring survive, the opposite may have been true in the primitive past, in which case k-selection would have better proliferated genes; so evolution programmed us toward that strategy of heavy investment in fewer offspring. In other words, we were bio-engineered for harsh conditions which no longer obtain. Which, somewhat paradoxically, is saving us from the Malthusian trap (by limiting reproduction).

But this doesn’t explain poor people – for whom conditions are still pretty harsh – generally favoring large families. More importantly, it seeks the answer in the wrong place; and this is actually a crucial point for us to understand. While human behavior is heavily influenced by genes, and the corresponding characteristics that evolution bred into us, we are not slaves to our genes. When it comes to behavior, genes give us predispositions, but not ironclad marching orders. Human beings have minds of their own, and other concerns, that can trump genetic predispositions.

images-1That’s free will. An individual with a genetic predisposition toward violence may never be violent. And what we’re talking about here is the most salient example: the one thing our genes most “want” us to do is reproduce, yet many people choose not to.

Thus it’s simply wrong to seek a biological/evolutionary explanation for the demographic transition. The answer lies instead in sociology and economics. Unknown-1People choose family size for reasons unrelated to our evolutionary background. To name just one, for poorer people children tend to be economic assets, helping them earn their bread and protecting their old age. Richer people don’t expect or need such protection or income contribution, and their children tend to be money pits, and a lot of work. Sure, many of us still choose to have some; but the sociological and economic influences are very different between rich and poor and they, not biology, drive the choices. It appears that humanity as a whole is moving toward a k-selection approach: fewer children, but living better lives, because that’s what we prefer, biology be damned.

Note that if poor families do fare better with more children, improving their joint survival, then genes for that behavior should spread (at least among the poor). Yet still, when those people get richer, they can and do ignore such genetic programming.

And that free will aspect is the larger point. Again, we are not like robots programmed by genes or biology; nor, for that matter, are we prisoners of sociology either. Even while all those influences matter, they do not compel us; we can still make our own choices.

images-2Some people think evolutionary biology implies Social Darwinism – leaving the less fit among us to their fate. But here too, the impersonal forces of nature that created us do not control how we choose to live our lives. As biologist T.H. Huxley observed, human society is not doomed to play out “survival of the fittest” but can, instead, work toward fitting more of us for survival. Our mission is not conformity to nature’s process but combating it.