Dumb Humans Think Humans Getting Dumber

Wait, Wait Don't Tell Me referred today to a study that claims human beings aren't as intelligent as they used to be.  I'd seen it mentioned once last week, but forgot about it; after an online search I realized that it was getting a fair amount of attention, so I read some of the articles and decided it was something I wanted to write about.

First, though, go back to this unrelated (or is it?) story from last March.

Work by Cornell University psychologist David Dunning and then-colleague Justin Kruger found that “incompetent people are inherently unable to judge the competence of other people, or the quality of those people’s ideas,” according to a report by Life’s Little Mysteries on the blog LiveScience.

“Very smart ideas are going to be hard for people to adopt, because most people don’t have the sophistication to recognize how good an idea is,” Dunning told Life’s Little Mysteries.

What’s worse is that with incompetence comes the illusion of superiority.

The irony in that last sentence sails over the researchers' heads, of course.  Hold that thought as I proceed.

Back to the articles (two so far) published by Stanford geneticist Gerald Crabtree on diminishing human intelligence.  I did some looking around for more information; tried to find Crabtree's articles themselves, but though I found the journal online through the university, I couldn't find the articles themselves.  I'll keep looking.

But for now, none of the reports indicate that Crabtree presented any evidence that human intelligence is in fact decreasing. Here's a summary of his argument from the Daily Mail:

Based on calculations of the frequency with which deleterious mutations appear in the human genome and the assumption that 2,000 to 5,000 genes are required for intellectual ability, Dr Crabtree estimates that within 3,000 years, about 120 generations, we have all sustained two or more mutations harmful to our intellectual or emotional stability.

Also, recent findings from neuroscience suggest that genes involved in brain function are uniquely susceptible to mutations.

Dr Crabtree argues that the combination of less selective pressure and the large number of easily affected genes is eroding our intellectual and emotional capabilities.

There is, I admit, no evidence Crabtree could present on human intelligence in history, because we have no good measure of intelligence for humans today (or any definition of intelligence that would enable us to measure it), and even if we did, we are unable to apply those measures to people who lived hundreds or thousands of years ago.  So what Crabtree has here is at best a hypothesis that he can't test, nor has he any prospect of being able to test it.  (Readers who take IQ tests seriously might want to recall the Flynn Effect, a documented rise in IQ scores that has been observed since the beginning of IQ testing.  But again, there's no way to administer IQ tests to our cavedwelling forerunners.)  According to a New York Daily News story, "Crabtree estimated that within 3,000 years, humans will endure two or more mutations harmful to our intellectual and emotional stability." Now, there's a testable prediction -- all we have to do is wait three thousand years, and then Dr Crabtree can collect his Nobel Prize!

So how does Crabtree argue for a decline in human intelligence?  He uses a well-worn canard, that human beings have gone soft over the millennia because we don't have to dodge saber-tooth tigers anymore.  As this writer quotes him:

"Needless to say a hunter gatherer that did not correctly conceive a solution to providing food or shelter probably died along with their progeny, while a modern Wall Street executive that made a similar conceptual mistake would receive a substantial bonus," Crabtree explains.

Crabtree gets a point or two for mocking the people who think they're the smart ones, but that may be why this blogger -- Web Editor for the San Francisco Business Times -- isn't all that impressed.  Still, he does a good job on a much quoted passage from the paper:

"I would be willing to wager that if an average citizen of 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," writes Crabtree (whose knowledge of Athenian history may not be quite as good as his obvious expertise in genetics -- he's chosen a date from the Dark Age in Greece, when writing was forgotten and "citizen" was a bit of a stretch, centuries before democracy, Pericles and his ilk -- ah, but I digress; read on, perhaps that's his point after all).

"We would be surprised by our time-visitor's memory, broad range of ideas and clear-sighted view of important issues. I would also guess that he or she would be among the most emotionally stable of our friends and colleagues," he goes on.

He adds, "I would also make this wager for the ancient inhabitants of Africa, Asia, India or the Americas, of perhaps 2,000 to 6,000 years ago."  So that's all right then.

I really must track down a copy of the paper, because I find it hard to believe that this drivel was published in a professional, peer-reviewed journal of genetics.  There's no science here, just speculation and fabulation: "I would be willing to wager ... We would be surprised ... I would also guess ..."  That and $2.50 will get you on the Metro.  It might fly on an Op-Ed page somewhere, but a scientist is supposed to give support for speculations, not just toss them out and treat them as fact.

It appears that Crabtree and his colleagues got their chronology mixed up in more serious ways. They place the peak of human intelligence before humans emerged from Africa, about 2 million years ago, with the long downhill slide following.  By two to six thousand years ago, most of those damaging mutations would have done their work.  There's no reason to believe that people who lived no more than six thousand years ago would be that different from people today -- but they would, on Crabtree's assumptions, be much more like us than they'd be like our shared African ancestors on the savannah.

The Daily Mail continued:

But the loss is quite slow, and judging by society's rapid pace of discovery and advancement, future technologies are bound to reveal solutions to the problem, Dr Crabtree believes.

He said: 'I think we will know each of the millions of human mutations that can compromise our intellectual function and how each of these mutations interact with each other and other processes as well as environmental influences.

'At that time, we may be able to magically correct any mutation that has occurred in all cells of any organism at any developmental stage.

'Thus, the brutish process of natural selection will be unnecessary.'

"Magically"?

There is a lot of question-begging going on here: one is that "intelligence" was a crucial factor in human survival.  It doesn't take a lot of intelligence to escape from saber-toothed tigers; many non-human species have done at least as well as we have in that area.  According to the San Francisco Business Times writer, Crabtree considers "building a house, washing the dishes and putting them away (yes, that's one of his examples), or surviving in the jungle" to be examples of high human intelligence in action.  He has an odd concept of intelligence.  Did our ancestors two million years ago wash dishes?  But again, surviving in the jungle and building shelter are not specifically human abilities.

The only criterion that really matters in natural selection is reproductive success, and human beings have done quite well at that -- too well, in many people's view.  Maybe "intelligence" isn't as vital to human evolution as we like to think.  The canard on which Crabtree builds his case, that Homo Sapiens spread all over the planet, in all kinds of hostile environments, by somehow escaping selective pressure, is an absurd misunderstanding of the theory of natural selection.  But it's a popular one. Someone posted this, linking to the Daily Mail article: "There's no longer survival of the fittest. Intelligence isn't necessary to simply survive."  Like many people this person misunderstands "survival of the fittest."  It doesn't mean fitness according to an abstract conception of superiority; it means fitness in a given environment, and has no meaning outside that environment.  In an environment where intelligence hindered reproductive success, less intelligence would be fitter and the environment would select for it.  If Crabtree were right, that would be exactly what has happened: as human beings became less intelligent, we became more successful.  (It wouldn't necessarily follow that lower intelligence was being selected for, of course.)  But whatever role intelligence played in human evolution -- and we don't really know what role it was -- intelligence of the same kind and level wasn't necessary for reproductive (and therefore evolutionary) success in most species.  This is so basic that I feel foolish spelling it out like this, but there it is.  Insofar as human activity has changed the environment, we have affected natural selection -- but we haven't bypassed it, let alone eliminated it or triumphed over it.  (For example, if our invention and use of antibiotics has led to the emergence of resistant strains of microbes, that's natural selection in action.  Scientists weren't trying to produce resistant strains; they were an unintended and unwelcome outcome of their work.)

The Independent quoted a grumpy geneticist on Crabtree's papers:

“At first sight this is a classic case of Arts Faculty science. Never mind the hypothesis, give me the data, and there aren’t any,” said Professor Steve Jones, a geneticist at University College London.

“I could just as well argue that mutations have reduced our aggression, our depression and our penis length but no journal would publish that. Why do they publish this?” Professor Jones said.

Notice that, contrary to Professor Jones, Crabtree isn't "Arts Faculty."  Like Jones, he's a geneticist, the head of a laboratory at Stanford Medical School that studies Developmental Genetics, Chemical Biology, and Chromatin Regulation. In fact it's usually faculty in the humanities who criticize this kind of biological reductionism.  As Mary Midgley wrote in Evolution as a Religion (Methuen, 1985): 

The effect [of specialization] is to leave many of today’s physical scientists rather unpracticed in general thinking, and therefore somewhat naïve and undefended against superstitions which dress themselves up as science.  Creationism, for instance, cuts no ice at all with humanists and social scientists.  Nobody trained to think historically is in any danger of taking it seriously, least of all theologians.  It makes its academic converts  among chemists and physicists – sometimes, alarmingly enough, even among biologists [24].

But Jones is right that Crabtree doesn't seem to have any data aside from some irrelevant (at least, their relevance isn't evident) calculations of the frequency of malign but unknown mutations that might affect human intelligence.  There's nothing necessarily wrong with putting out untestable speculations, but they don't constitute confirmation or proof of anything.

So why do "they" publish this?  I wonder that myself.  But it's easy to see why it got so much attention.  The thesis is a popular one among social Darwinists, who like to think that the race has gone soft due to luxurious living, and the Stupid are inheriting the earth, instead of their own superior selves. Which takes me back to the quotation above: With incompetence comes the illusion of superiority.