There is no female Mozart because there is no female Jack the Ripper.

— Camille Paglia

Here are three stories of stupidity. See if you can spot what they have in common.

In the year 2000, an Iraqi terrorist called Khay Rahnajet decided to send out a letter bomb, but he forgot to put enough postage stamps on the letter, meaning it came back ‘return to sender’. Khay was so happy to receive some post that he ripped it open. And that was the end of his terrorist career.
Then there’s the guy who tried to steal a metal cable from a lift shaft whilst inside the lift causing it to plummet to the ground.
Finally, we have the case of someone who tried to steal a ride home by hitching a shopping trolley to back of a train, only to be dragged two miles to his death before the train was able to stop.

So, what’s the link? Yes, they’re all men and yes they’re all idiots. But they also all successfully removed themselves from the gene pool, winning themselves Darwin Awards. Winners of the Darwin Award must die in such an idiotic manner that:

[…] their action ensures the long-term survival of the species, by selectively allowing one less idiot to survive.

The Darwin Award has been going since 1994. In 2014, a few academics looked at the sex differences in award winners. Predictably, 88.7% were men. The authors have a tongue-in-cheek explanation for this sex difference:

According to “male idiot theory” (MIT) many of the differences in risk seeking behaviour, emergency department admissions, and mortality may be explained by the observation that men are idiots and idiots do stupid things.

So the question is: are men just more likely to do stupid things or are there more idiotic men than idiotic women? Of course, these propositions aren’t mutually exclusive. Another equally interesting question is: if there are more idiotic men than women, does this balance out at the other extreme? Are there more very smart men than very smart women?

Of course, it depends on how we’re defining idiocy and intelligence. IQ has proven to be the most rigorous predicative tool in all of psychology, especially for the low end of the distribution. It certainly doesn’t capture everything about intelligence, but it probably captures enough to help answer this question. To illustrate this predicative power, let’s look at the life chances for the bottom 5 and top 5 per cent of the IQ distribution. (To be in the bottom 5 per cent means IQ 75 and below. The top 5 per cent is IQ 125 and above).

Linda Gottfredson, an international expert in such matters, labels these groups “high risk” and “yours to lose”, respectively. Why? Well if you’re in the top group, you could be born into relative poverty, but the chances you’ll escape it in a modern market society are virtually guaranteed. To be precise, you’d have a 2% chance of living in poverty. For those unlucky enough to have be born with an IQ of 75 and below, this figure rises to 30%! What else?

Divorce rate after five years of marriage: Yours To Lose ≈ 9%, High Risk ≈ 21%
A woman’s chances of being on welfare after her first child: Yours To Lose ≈ 1%, High Risk ≈ 55%
Mothers who are chronic welfare recipients: Yours To Lose ≈ 0%, High Risk ≈ 31%
High school dropouts: Yours To Lose ≈ 0%, High Risk ≈ 55%

And that’s why Gottfredson chose the labels. Indeed, The Diagnostic and Statistical Manual of Mental Disorders (colloquially known as the DSM) concurs. As part of the diagnostic criteria for “intellectual developmental disorder”, individuals must have an IQ of 70 or below. (“Intellectual developmental disorder” was previously known as mental retardation, but the name was changed due to its negative connotations.) Gottfredson’s data show how cruel the genetic lottery is, how rigged the game is.

But back to our primary question: how many men and women are in these groups? Some of the best evidence we have comes from two population wide surveys of 75,000 and 87,000 Scottish 11 year-olds. In these samples, we see twice as many males as females at IQ 60, providing good evidence for Male Idiot Theory.

And what about the the top end? At IQ 132, (which is the 98th percentile) we see a male to female ratio of 1.4. The further up we go, the higher the ratio gets. At IQ 140, the ratio is 2.0 and 2.3 in each data set. So at least twice as many males as females. The Handbook of Gender Research in Psychology describes this study as:

[…] groundbreaking in their illustration of gender differences in variability on intelligence tests.

But what about subject specific tests? What about that stereotype that girls are more “verbally tilted”, whilst boys are more “numerically tilted”, to use the research jargon. Well, The Early Childhood Longitudinal Study allows us to look at the top 5% of students taking standardised cognitive tests at six points during their observation from 5 years of age to 14. This is what we see:

There are more males at each level, other than the ones I’ve highlighted.

When we get to the top 0.5%, the ratios are staggering. Here’s the same data with the final column highlighted yellow:

If we average out these tests, there are three times as many top male mathematicians and over four times as many top male scientists.

Reading ability is a domain which favours females — they’re overrepresented in the top 10% (as are boys in the bottom 10%). Yet when we get to the top 0.5%, we find that, even here, there are more boys. There’s also a good chance that these gaps grow larger with age, as males develop more of an advantage after puberty. Remember, the Scottish data looked at 11 year-olds and the American data stops at age 14!

Of course, there are caveats to this research that we’ll come to later. But let’s put what we’ve learnt so far into perspective.

First, the ratios of very unintelligent males and very intelligent males to that of very unintelligent females and very intelligent females get larger the further down or the further up we go in the results of IQ tests. Second, the ratios are even higher in subject specific tests (with some exceptions for verbal ability until we hit the top 0.5%).

There are 250 million working age adults in the US. This means that the bottom and top 0.5% (250,000 people) is likely to include at least twice as many men as women in terms of a measure like IQ or mathematical ability. This helps to explain the preponderance of both male idiots and male Nobel prize winners for physics.

But why do we see greater male variation?

Greater male variance across traits is a well established biological fact. There’s more male variation in physiology (weight, height, BMI, arm length, pulse, blood pressure etc), sexually selected attributes (physical aggression, good looks, ambition and industriousness, good financial prospects), and though personality shows less male variation, it’s still there.

The most male variation we ever see is in the male brain (both overall and at regional levels), which partly answers our question about intelligence extremes. In 136 measures of brain volume and surface areas, men vary more on 134 of them. However, brain size only explains 6–12% of the variance in intelligence, so it’s not as simple as bigger brains always equal smarter people. Indeed, women have greater cortical thickness to make up for this disparity.

Of course, I haven’t really explained why the greater variation is there. The precise mechanisms are still debated. However, most evolutionary biologists conclude that males vary more in order to increase their chances of reproduction. Being able to attract the opposite sex is far more important for males than females. Take the fruit fly as an example (a staple of genetic research): 20% of males fail to reproduce, compared to 4% of females. And those 4% just aren’t interested, it’s not like they’re not attracting potential mates, they just don’t seem to care. Females can be and need to be as choosey as possible because they bear the overwhelming costs of offspring. In fact, in 95% of mammalian species males make extremely small parental investments whilst females make immense ones. This imbalance can produce greater male variability via different routes.

Most males of most mammalian species will mate with anything that has a pulse, as the saying goes. So you have selection pressures to develop traits which will enable you to fight off competitors and attract females. Meanwhile, the female faces none of this evolutionary pressure, so any deviations from the normal range could result in fitness costs.

The evolutionary pressures on males resulted in intra-sex competition (males versus males). Females would then, unconsciously of course, select mates based on proxies for intelligence: for example, greater mastery of craft, tool use, or general inventiveness. That is the evolutionary logic in a nutshell: if females are relatively selective from one generation to the next, more variable subpopulations of the males will generally tend to prevail over those with lesser variability.

Trillions of such events took place over millions of years, meaning that even fractional fitness advantages started to add up. Today, this dynamic between male and female humans is probably a lot weaker. Modern human males usually make a much higher parental investment than other mammals. But does any of this matter? After all, the researchers of the Scottish study note:

Though present at the high end of the distribution, sex differences in variability did not appear to account for sex differences in high-level achievement.

Overall, we still see women doing better in educational attainment at every single stage, from elementary/primary school to graduate university level. As the Harvard psychologist Elizabeth Spelke has pointed out:

[…] classroom performance is at least as important as standardised test results, because grades reflect students’ ability to learn and to apply challenging new material.

Regardless of IQ differences at the low and high ends, women in those bands still have more years in school and get more degrees. There are many reasons for this and it’s beyond the scope of this article to unpack, but I already mentioned one big one: IQ isn’t a perfect measure of intelligence and there’s a lot more to getting good grades than just raw brain power.

In sum: if you want to risk death chasing cheese down a hill, or if you want to be homeless, a suicide victim, or in prison, then, all things being equal, be born male. At the other extreme, if you want to win a Fields Medal, a Nobel Prize, or become World Chess Champion, then, all things being equal, be born male, too.

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Ideas Sleep Furiously

Most geniuses will always be men