Skip to comments.Is human intellect on the downward slide?
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). Crabtrees thesis: humanity is almost certainly losing its superior intellectual and emotional capacities.
Crabtree doesnt 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 Crabtrees inferred date of humanitys intellectual zenith.
And he doesnt 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. Hes arguing that humans throughout the world have been steadily losing their marbles for the last three to six millenia.
Well, Professor Crabtree, Ill see your Athenian intellectual Titan. And Ill raise you a bottle of 1998 St Henri and a $100 book voucher.
Did human intellectual capacity peak 600 years before Plato? Raphaels Scuola di Atene fresco in the Vatican, 1511. Wikimedia commons
Im 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 doesnt stand basic scrutiny.
So many ways of being dumber
Crabtrees 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 dont simply each contribute a tiny bit to intelligence, with the genetic component of any individuals 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 Darwins early supporters. And by creators of museum dioramas.
Which explains why Crabtree thinks humanitys 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 Crabtrees 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 Shusters estimate that sexual selection accounts for 55 per cent of total selection in Homo sapiens. Or take Greg Clarks 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 isnt via natural selection.
No. Culture and learning are in decline, not intelligence, which is innate. Natural selection does not account for decline, if there is such. Human intelligence varies little from person to person. A few geniuses and some regards, but most people are moderately stupid.
No. Culture and learning are in decline, not intelligence, which is innate. Natural selection does not account for decline, if there is such. Human intelligence varies little from person to person. A few geniuses and some retards, but most people are moderately stupid.
Are we not men?
Moderately to incredibly. You can’t refute the stupidity of Obama voters.
That could explain why the Nobel Committee gives prizes to people
like Gore and Krugman. Who’s next, Steven Tyler?
- we have a very broad and abundant source of food (e.g. we get tomatoes in or out of season)
- most responsible parents start stimulating our children's intellect upon birth (some try before birth)
- we have added more knowledge over the last 50 yeas than in all of human history and made it readily available
So I think any degradation would be due to overly processed foods, too many drugs, and toxins from our high tech world getting into our food and air.
NO! (I’m too stupid to know it is) LOL
Only in certain groups because primitive peoples are supplanting the more advanced
And will drag us all down
There was a time, not that long ago, when most people were not as arithmetically challenged as comrade obama, and could add and subtract without a calculator.
Our socialist society has reversed the trend of the rich having more children than the poor. Socialist welfare programs have made it possible for the poor to have many more children than the rich. The welfare programs have put in place financial incentives for the poor to produce more children.
The poor are not necessarily less intelligent than the rich but certainly they are less productive. The poors lack of productivity is however some evidence of inferior intelligence.
Or maybe some of the peoples of South America, people who mastered their environment to the extent they were able to build cities on mountain tops with a mastery of stone superior to anyone in the world.
But like flowers that bloom for a time they all withered and disappeared without ever understanding why. Maybe they weren't so smart after all.
Watch who breeds and who doesn't.
Watch the genealogy chart of the "smart" shrink, while the chart of the "dumb" expands.
Buy it so you can watch it a few times to pick up the nuances..
It is a somewhat vulgar, but very timely movie.
I'm almost seventy, driving a cab fifty hours a week (in "retirement" ;O)) and a couple of days a week my relief driver is a twenty-six yo woman.
After gassing up the other night, I glanced at my receipt, glanced at the odometer and announced that I had gotten about 19 mpg from the old pig taxi.
It took about two seconds.
Her response? "That's scary."
In ten generations it's still pretty much to the average, and in 100, or 1000 generations, it's the same old same old.
Even most of our genes are not terribly different than those of our most ancient spongoid ancestors, or even bacteria!
The tools in the DNA that put together a liver, for example, are pretty much the same in every species with a liver.
So, what makes the difference?
The big boys in the new field of epigenetics say it's the extra copies, the sequence and the blanks, and the bypasses (many due to methylation) that make the difference ~ and that's a pretty complex piece of work ~ and neither Darwinian nor any other view of evolution and survival of the fittest can do more than say 'see there, it works' ~ how it works has yet to be determined.
The writer's thesis is that easy eats (agriculture) allow the less fit to survive.
presumably taking their food away will make them smarter ~ (snork/s)
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