Did human intellectual capacity peak 600 years before Plato? Raphael’s Scuola di Atene fresco in the Vatican, 1511. Wikimedia commons
Posted on 11/22/2012 12:06:23 AM PST by LibWhacker
I would wager that if an average citizen from Athens of 1000 BC were to appear suddenly among us, he or she would be among the brightest and most intellectually alive of our colleagues and companions, with a good memory, a broad range of ideas, and a clear-sighted view of important issues.
So Stanford geneticist Gerald R. Crabtree begins back-to-back Forum pieces for Trends in Genetics, entitled “Our Fragile Intellect” (Parts I and II). Crabtree’s thesis: humanity is “almost certainly” losing its superior intellectual and emotional capacities.
Crabtree doesn’t seem to be arguing for the intellectual vibrancy of the Akademia or the Lyceum. These places, and their celebrated occupants like Plato and Aristotle graced Athens only 600 years later, well beyond Crabtree’s inferred date of humanity’s intellectual zenith.
And he doesn’t confine himself to Athens. “I would also like to make this wager”, he goes on, “for the ancient inhabitants of Africa, Asia, India, or the Americas, of perhaps 2000-6000 years ago.” He’s arguing that humans – throughout the world – have been steadily losing their marbles for the last three to six millenia.
Well, Professor Crabtree, I’ll see your Athenian intellectual Titan. And I’ll raise you a bottle of 1998 St Henri and a $100 book voucher.
Did human intellectual capacity peak 600 years before Plato? Raphael’s Scuola di Atene fresco in the Vatican, 1511. Wikimedia commons
I’m not at all opposed to expansive predictions. But they should be tempered by critical thought. And wherever possible they should be reformulated as hypotheses and tested. Crabtree makes a few predictions that should, with progress in genomics, become testable. But it may surprise you to learn that his argument for why our intellect is fragile doesn’t stand basic scrutiny.
So many ways of being dumber
Crabtree’s main point boils down to this: human intellectual function depends on the action of lots of genes. In Part I, Crabtree briefly reviews the evidence that more than ten percent of all human genes – 2000 to 5000 in all – contribute to human intellectual and emotional function.
These genes don’t simply each contribute a tiny bit to intelligence, with the genetic component of any individual’s IQ being the sum of all these minute contributions. Instead, they interact “as links in a chain, failure of any one of which leads to intellectual disability”. The idea that various genes interact is far from controversial. But the case that breaking any one of these genetic links can be catastrophic does not compel me. I am sure that many crucial genes behave this way, but I would be staggered if every one of the 2-5000 was quite so brittle in its functioning.
With so many genes involved, it becomes a mathematic certainty that in the 120 or so generations since the pre-Golden-Age bronze-age “golden age” of the Athenian intellect, “we have all sustained two or more mutations harmful to our intellectual and emotional stability”.
There is some serious genetics behind this argument, and while the conclusions might not follow as crisply as Crabtree argues, it makes for an interesting read on the big-picture state of intelligence genetics. But would selection not have eliminated most of those mistakes?
Crabtree recognises that his case for genetic fragility of the human intellect conceals a flaw: if the human intellect is so fragile, then how could it have evolved to reach the mythic Olympus it inhabited 3000 years ago? In Part II, Crabtree lays out his theory for the main selective forces that shaped human intelligence, and for how changes in the last few thousand years have relaxed that selection. “Extraordinary natural selection”, he argues, “was necessary to optimize and maintain such a large set of intelligence genes”.
And where did that selection come from? Crabtree has some ideas: Errors of judgment. Inability to comprehend the aerodynamics and gyroscopic stabilization of a spear while hunting a large, dangerous animal. Finding adequate food and shelter.
In short, selection happens as a result of not dying. In the kind of world in which merely prevailing over the elements, slaying the occasional mammoth and keeping warm on a cold evening ensured success. The “Survival of the Fittest” world beloved of Darwin’s early supporters. And by creators of museum dioramas.
Which explains why Crabtree thinks humanity’s slide began three millenia before Big Brother even started filming. Agriculture and high-density living, he argued, in selecting for immune resistance to epidemic diseases might have softened selection on intelligence. And that living communally probably reduced the relentless selection by buffering our ancestors from mistakes in judgement and comprehension.
The idea that group living dimmed the harsh selection on day-to-day survival skills intrigues me, and certainly merits testing. But to suggest that this was the end rather than a Renaissance for selection on intelligence reflects a narrow view of how selection works, particularly in humans.
Selection – a social and sexual situation
When The Conversation editor, Matt de Neef drew my attention to Crabtree’s articles last week, I was preparing a keynote talk at the Applied Linguistics Association of Australia conference in Perth on the evolution of language. While the deep evolutionary causes by which human capacity for language emerged remain murky and contentions, the ways in which we use language today reveal a lot about the forces that have shaped and embellished our capacity for speech, and for writing and comprehending it.
As societies grew larger and more complex, our social worlds grew apace. More people to interact with every day, to speak with, to manipulate and to avoid being manipulated by. More people to court, and more ardent and eloquent suitors to thwart (or accept). The skills that made our ancestors successful shifted; from survival Bear Grylls style to navigating sexual, social and status complexity Sex and the City style.
A few days ago Jason Collins, made exactly this important point in his excellent blog Evolving Economics:
The problem is that Crabtree does not see sexual selection as an “extreme” selective force, when it is. Consider Wade and Shuster’s estimate that sexual selection accounts for 55 per cent of total selection in Homo sapiens. Or take Greg Clark’s data from A Farewell to Alms, with the rich having twice the children of the poor. The link between resources and reproductive success is strong across societies, and assuming a link between resources and intelligence (which if anything appears to be getting stronger), the intelligent have been reaping a reproductive bounty for some time. For those less fortunate, survival without reproduction is still a genetic dead-end.
Humans are complex animals. Our intelligence is a complex adaptation. And the diverse and surprising ways in which we use it today suggest that we owe it to more than a handful of simplistic evolutionary scenarios. Recent evidence suggests that the advent of farming did not halt the course of natural selection, but rather that it diverted it. From where we stand it is almost impossible to discern what directions human evolution, including the evolution of our intellects, might currently be taking.
But I would gladly wage that if humanity is getting dumber it isn’t via natural selection.
The Chinese intellectual classes appear to have done much the same thing unless their lives depended on it ~ which suggests we can all become quite a bit smarter if tortured every now and then!
Many years ago in a long flight I was studying a calculus textbook (strictly for my enjoyment) when a fellow passenger said to me that with the advent of the calculator that subject was obsolete. He never did tell me which button you push to improve your brain.
Not really a ‘new’ field, but becoming much more of a focus now that it has become apparent that sequencing the genome wasn't the holy grail some had hoped. I've recently seen genetically identical twins who, as adults, are not the same height. Clearly ‘nuture’, including likely epigenetic modifications (such as the methylation you mention), plays a big role.
Having said that, the fact that we don't feed people to the lions in this century isn't because our DNA changed - or our methylation patterns are different. It's because humanity learned lessons that were passed on from generation to generation. If we stop passing on that which we've learned, those lessons can be lost.
So maybe this is an upside of reelecting Obama?
Noticed he lost 6.5 million voters last time around!
I would say the causes are more cultural. Since the eighties I have noticed the “dumb is kewl” trend. Add to that the sad state of dumbing down of public schools, and the school administration enforcing the “crab bucket” mentality.
I have seen that movie, and concluded that we are 80% there.
Which is doubtless why Japan, Russia, and Europe are all demographically imploding, while the Muslims, Indians, and Chinese are all booming (female infanticide and China's one-child policy notwithstanding...)
Cheers!
Only at the top of American government and courts.
That would be a step up.
A friend in Germany can't understand my dislike of the usurper - "But, but he got a Nobel Prize!!!!"
Whenever an athiest calls into his show and says the only hope that man has is to progress as a species Dennis Prager always responds that he thinks humans are getting dumber and asks the caller to compare letters we have from Civil War Soldiers (who usually only had at most an 8th grade education) to writings today. Oh well, gotta go watch “Ow My Balls!!!”
Need to ask? Just check the election results.
Probably on purpose. If a certain group that is seeking power wanted more power in a representative republic, they need control of a large, unquestioning voting block who lack critical thinking.
The entire premise of the "family oriented" The Cosby Show is that dad is dumb (even though he's a Dr), the kids are dumb, mom is the only smart one because she's authoritative and thinks critically, so don't bother with your own agenda, just follow mom's directives. Scale that up - with a government official as "mom", and constituents as family members - then you have the democRat party.
I have no doubt that the average Athenian of the golden age of Greece was highly intelligent. The city at it’s height was only around 100,000 yet they produced a huge number of the world’s greatest playwrights, philosophers, mathematicians etc.
At 1000 BC Athens was probably less than 10,000 with most of them living on the acropolis which would have been walled in. The fact that the acropolis was a very protected location and was close enough to the harbor at Piraeus is why the city developed. Also the Provence of Attica was apparently a fertile farming area.
The coming Agenda 21-sponsored worldwide famine will sharpen up the wits of the survivors.
I don't believe this is true at all. The bell curve is real. The bottom 10% are way below the top 10%. But averages are misleading.
Let us say there are 100 people. The bottom 10% have an IQ of 65, the top 10% at 130 (I'm just making these up.)against an average of 100. Eliminating the bottom 10% ups the 'average' intelligence to 103, but the society is not really smarter - just fewer dumb ones.
The real question is, was Hawking smarter than Einstein? Davinci smarter than Hawking?
Idiocracy oz fine, but completely falls apart if you look too closely at the premise. Firstly it’s just plain wrong on evolution. Secondly I kept expecting it to turn out that a few smarties were secretly running the country. A nation if idiots could live off the accumulated capital of our cibilization for a while. It’s easier to maintain electricity or the combustion engine, for instance, once you’ve invented them. And the idiots in the movie weren’t doing we’ll.
Still, they seemed to be doing too well for their abilities. They have a crop crisis, buildings are falling, you can escape from prison by telling a guard today is your release day, etc. But I think they’d all have starved to death by then in the real world.
Thirdly and finally they associated idiocy with Big Business, which makes sense in the sense that Carl’s Jr., Starbucks, or whatever, cater to idiots. That doesn’t mean, however, that you can be an idiot and run a corporation. Perhaps the CEO and any number of executives can be idiots, but someone somewhere has to know what they’re doing. This is also why I expected hidden smart people.
Maybe there was no central management and each individual franchise outlet ran itself autonomously, sorta carried on by inertia. But no, it takes some intelligence to run small businesses, surely. Not much to offer a shelter within which you give sexual release, but something to keep feeding people for as long as the idiots have lived.
No, it’s not epigenetics that makes the difference intellectually. Nor is it a lack of sufficiently rigorous natural selection. It is not biological at all. My assumption is innate intelligence has not changed since the advent of civilization. What makes groups smarter or stupider since then is learning, or a lack thereof.
Evolutionary science is really bad at history, economics, anthropology, and sociology, though decent at psychology. A perfect example is the povetyy of sociobiology. It lacks the equipment to understand experience, ir the world of “nurture.” Though it does have a few things to say about biological changes after the advent of of the organism, it is largely helpless in the face of culture.
Because its disciplined line can only in a robust manner explain how wewe’ve been generally for 65,000 years or so. It cannot explain at all, for instance, baseball or Beethoven except in very, very extremely general terms.
“the less fit to survive”
That is a contradiction. Fitness is defined as what us fit fir suurvival. If something survives it is by definition fit.
What you or they mean is the less intelligent survive. But that is simply not true. Average human intelligence, so far as we know, has stayed about the same since there have been humans. What’s happened, if anything, is that already born humans have been miseducated.
“I don’t believe this is true at all. The bell curve is real.”
Yes, it is. I’m nit saying there is nothing but the average. My post clearly admits the existence of born geniuses and retards. However, most people are in the middle range, wherever that happens to fall, and whatever else changes that range never moves drastically left or right from generation to generation.
When I say intelligence doesn’t vary much from person to person, obviously if you line up a genius and a deranged person between two normals it does. But not amongst normals. And in any case the main point is that over time the distribution of geniuses, retards, and normals stays constant.
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