Chicks Dig Jerks, Right?

January 1, 2015


Milhouse putting on his bad boy-suit for Liza.

The Bad Boy Allure

There is a widespread notion that girls and women have a thing for bad boys. Sure, they say they like nice guys, who are attentive and caring, who play by the rules, and whom you can trust. But in reality, they prefer the arrogant, self-centered, manipulative guys – the bad boys or jerks.

We find this theme in literature, films and TV shows ranging from the dark attraction of cold-blooded serial killers, the seductive charm of vampires to more light stuff like the TV show The Simpsons, where the straight-A student Lisa falls for the unsophisticated bully Nelson.

This view is also held by the boys and men of the manosphere, an online community about gender issues from a male perspective, inspired by evolutionary psychology, pick-up artistry and personal experiences. Here too the consensus seems to be that chicks dig their jerks, only with the dark, optimistic belief that you can and should learn how to be a jerk, or in their biologically inspired jargon, an alpha male.

While this consensus is intriguing, it’s not necessarily compelling. For one, consensus varies over time. We used to believe in the existence of witches but now that belief might get you a psychiatric diagnosis. And it varies by population. According to PEW, most Buddhists and Hindus embrace the theory of evolution, but only a small minority of Mormons and Jehovah’s Witnesses do so. In short, consensus is no substitute for evidence. And neither is the cynicism of the manosphere, for that matter. So is there any evidence?

Attraction Research

As one might expect, there is plenty of research on what women look for in men, and vice versa. In a huge international and cross-cultural study (possibly the largest of its kind), psychologist David Buss and colleagues asked 10 000 participants what characteristics they desire in a potential marriage partner. Most of the top ten turned out to be personality traits, things like sociability, pleasing disposition, dependability, emotional stability, ambition, refinement/neatness, and intelligence (which not everyone views as a personality trait). All of these were considered more important than things like for instance financial prospects, social status or religious and political background.

But the desirable traits listed above do not paint a picture of a bad boy – or girl for that matter, as the difference between the sexes was very small. In Big Five terms it translates to extraversion, agreeableness, conscientiousness, and lack of neuroticism. The bad boy, however, is not well captured in the Big Five model, but matches the Dark Triad (DT) traits of psychopathy, narcissism, and Machiavellianism. As no test of this triad was included we can’t tell for sure, but correlations between DT and Big Five are positive for extraversion and emotional stability, but negative for agreeableness and conscientiousness. And there is nothing “dark” per se about an extraverted and emotionally stable person. So it’s clear that, these findings can’t support the chicks-dig-jerks theory as correlations fail to match DT, and with “dependability” and “pleasing disposition” as two conspicuous deal breakers.

Besides these desired traits, there is also research showing that people of both genders like those similar to themselves. All Big Five show moderate correlations between how much a person likes a trait in a partner and how much he or she has of that trait. This birds-of-a-feather effect goes beyond personality, as Buss explains,

For nearly every variable that has been examined— from single actions to ethnic and racial status—people seem to select mates who are similar to themselves. Even for physical characteristics such as height, weight, and, astonishingly, nose breadth and earlobe length, couples show positive correlations. Indeed, the only characteristic on which “opposites attract” that has been reliably documented is biological sex: Men tend to be attracted to women and women tend to be attracted to men.

But as both psychologists and members of the manosphere have pointed out, women may want jerks or bad boys for short-term relationships rather than for marriage. So let’s push onwards and explore that possibility as well…

Women’s Flings

In doing so, we immediately hit an obstacle. Because if it is generally true that chicks dig jerks, it would also mean that women in general enjoy short-term relationships. There is, however, a lot of research that says the opposite. Here is some taken mostly from Randy Larsen and David Buss’ book Personality Psychology – Domains of Knowledge About Human Nature (2010) and Buss’ Evolutionary Psychology -The New Science of the Mind (2007),

As far as sexual fantasies goes here is a N=1500 study from last year, showing 83 percent of men having the fantasy of sex with someone other than their partner, as compared to 56 percent for women.

From Wikipedia: The National Health and Social Life Survey found that 4% of married men, 16% of cohabiting men, and 37% of dating men engaged in acts of sexual infidelity compared to 1% of married women, 8% of cohabiting women, and 17% of women in dating relationships (Lalasz & Weigel, 2011) (If someone has a full-text of this article please let me know.)

69 percent of men had solicited a prostitute, less than one percent of the women had done so.

Men report wishing on average 18 sex partners over their lifetime, while women want on average 4.

Four men in a lifetime. That alone gives us a hint of just how uninterested most women must be in short-term relationships – and, as a consequence, the men who provide that type of experience.

Still, some psychologists appear very fond of this idea and are conducting research into the possibility of Dark Triad traits having evolved as a strategy for short-term sexual encounters. And if this is the case they should be attractive to women. So let’s hear them out as well…

Physical Attractiveness

One idea is that women can tell just by looking at Dark Triad men, by facial or other bodily characteristics, that they have some superior genetic qualities. In a study looking into this, psychologist April Bleske-Rechek and colleagues (2008) had 102 participants (51 couples) rate how attractive and sexy they think they are compared to other people. As expected, narcissism scores correlated with how hot participants thought they were. The main finding, though, was that a panel of 17 judges of both sexes, who showed strong consensus in all their ratings, found the narcissist to be no more or less attractive than other participants. This after being shown face pictures. So it’s possible that full body pics would have produced a different result, but the authors claim that facial attractiveness is a good predictor of general attractiveness. At any rate the study lent no support to the idea of facial symmetry, a compelling gaze or whatever, as a visual indication of some biological sexiness.

In another study, psychologists Nicholas Holztman and Michael Strube (2013) looked at the relationship between attractiveness and personality with a special focus on adorned versus unadorned attractiveness as well as effective adornment, which is how much your adornment will improve your attractiveness. Note that effective adornment is not merely a matter of skill as some people use adornment very skilfully for personal expression or according to what is appropriate for the occasion, rather than to make themselves attractive. While in the study mentioned above, Bleske-Rechek controlled for how much participants were smiling and for resource display, previous research has not specifically distinguished between the adorned and unadorned condition.

Holztman & Strube had 111 students full body pictures taken as they entered the lab in their normal clothes, makeup etc, that being the adorned condition, and then dressed in grey clothes with makeup, jewelry, men’s facial hair, and so on, all removed in the unadorned condition. They combined self- and peer ratings of personality, a good way to reduce measurement error, and used students of the opposite sex, not previously acquainted with the participants to rate their attractiveness. In line with Bleske-Rechek’s study, they found very small correlations between unadorned attractiveness and personality, the biggest being 0.23 for extraversion – known as a desired trait for long-term relationships. The other personality trait measures of Big Five, a Dark Triad composite measure as well as its individual scales were all below 0.1. One measure of Narcissistic Personality Disorder (NPD) reached 0.20, so extreme cases of narcissism were on level with regular extraversion.

Again, this is not much to build a chicks-dig-jerks case on, especially as the only link between attractiveness and Dark Triad was a clinical measure, and the size of the correlation was rather modest. But it would be interesting to compare the result with correlations with other clinical measures of things like schizotypy, Borderline Personality Disorder.

Peacocking and Persona

As for the adorned condition, bad boys did slightly better. The Dark Triad composite reached 0.20 and the highest correlation was for NPD at 0.26, with extraversion second at 0.25. (All other Big Five correlations were very low as in the unadorned condition.) Dark Triad was also associated with effective adornment, the ability to enhance attractiveness by adornment, which is no surprise as people with dark traits by definition put a lot of effort into portraying themselves favourably as a way to manipulate and exploit other people.

But again, the effect is not striking and it raises questions about whether women are superficial or easily tricked rather than crazy about Dark Triad people per se. An attractive veneer signals things like physical fitness and material wealth, characteristics that were considered attractive according to Buss’ cross-cultural study mentioned above. So that only means bad boys try to come across as conventionally attractive by displaying some attributes that they may or may not possess. Indeed, there would be little point of hiding their person behind a veneer if it was the person that was the attraction. And yet, many Dark Triad people go to great length to not only create a physical veneer, but also a psychological one, a persona or mask that sometimes contrasts sharply against their real personality. As an example, consider crime author Ann Rule’s description of psychopathic serial killer Ted Bundy, a man she had spent a long time with before discovering who he really was,

Ted’s treatment of me was the kind of old-world gallantry that he invariably showed toward any woman I ever saw him with, and I found it appealing. He always insisted on seeing me safely to my car when my shift at the Crisis Clinic was over in the wee hours of the morning. He stood by until I was safely inside my car, doors locked and engine started, waving to me as I headed for home twenty miles away. He often told me, “Be careful. I don’t want anything to happen to you.”

Compared to my old friends, the Seattle homicide detectives, who routinely saw me leave their offices after a night’s interviewing, at midnight in downtown Seattle with a laughing, “We’ll watch out the window and if anyone mugs you, we’ll call 911,” Ted was a like a knight in shining armor.

So why would a bad boy impersonate a nice guy to attract women when it’s the bad boy they want?

A Flirt with the Devil?

But still. That’s anecdotal, and other anecdotal information goes in the other direction. As popular manosphere blogger Heartiste so charmingly puts it,

I’ve never gotten more radical, more INSTANT, positive results when hitting on cute babes than when I deliberately amped up my asshole vibe. I mean, to the point of nearly insulting them. Eyes brightened and sparkled, legs uncrossed, fingertips danced all over my arms. And these were the upper class smart chicks with multiple degrees.

Can we rule out that women are attracted to the bad boys because they are bad? It could be the thrill of a dangerous man, or they may think of these guys as the alpha male winners they see themselves as.

There are studies on this too. One is by psychologists John Rautmann and Gerald Kolar (2013), and another one by Gregory Carter and colleagues (2014). Both eliminated the veneer of physical appearance, resource display etc by using vignettes, fictional descriptions based on the so-called Dirty Dozen measure, a short Dark Triad composite questionnaire. In order to see if the vignettes were perceived as Dark Triad and to control for other traits, both studies also had participants rank the vignette characters on the Big Five. Overall, these ratings were as expected, high on extraversion, lower on agreeableness, neuroticism and conscientiousness while more or less unrelated to openness. (There were some discrepancies however, more on that later.)

Rautmann & Kolar created vignette characters separately for each of the three DT traits which participants rated on various types of attractiveness – likeability, friendship material, general attractiveness, as a potential partner in long- and short-term sexual relationships. It turned out that these characters rated fairly low on most scales. All but two ratings were below the neutral/disinterested midpoint of 2 (going from 0 to 4) of the five point Likert scale. These were for narcissists and Machiavellians on short-term sexual relationship, scoring 2.42 and 2.05 respectively, the latter being negligibly over the neutral rating. Or as the authors sum it up – “Narcisssists are perceived as hot, Machiavellians and psychopaths not.”

This might look as a win for the chicks-dig-jerks theory, at least in the case of narcissists. But scoring 2.42 on a scale from 0 to 4 is not a striking result. The authors also concede that the vignettes don’t take into account that DT traits are intercorrelated. This means that real life narcissists will be somewhat psychopathic and Machiavellian as well, which should reduce their modest attractiveness ratings even further. Then there is the Big Five rating which showed that participants viewed narcissists as more normal and, as a consequence, less bad or dark, than psychopaths and Machiavellians. In terms of Big Five correlates it was the psychopaths who rated darkest, scoring lower on neuroticism and agreeableness, suggestive of a cold-blooded and hostile person. Interestingly, psychopaths also scored lowest on attractiveness – including the scale for short-term sexual interest. Again, not good news for this theory.

At Least Sexier Than Nervous Geeks?

Carter and colleagues, however, got a different result. They created a composite DT vignette character, rather than one for each part of the triad, and this character rated as relatively attractive. And unlike Rautmann & Kolar, Carter introduced a control character too so that we can see how attractive the DT vignette was compared to an average guy. Well, that would have been the obvious way to do it, but instead they went with a control character that simply lacked all DT traits. And as traits tend to be normally distributed, meaning most people are close to the average, the control in this study is just as rare and extreme person as the Dark Triad person. What kind of person?

Judging by the Big Five traits that participants rated the control with, this was an introverted, neurotic and conscientious person, or in more plain English, an unsociable, nervous, geeky guy. Not that I have any evidence that such a person would score as less attractive than most personalities, but I think we can agree that it’s reasonable to suspect that correlations between DT personality and attractiveness may have been inflated in this way. Even so, the correlation was not more than 0.37 as compared with -0.35 for neuroticism and 0.33 for extraversion. The authors also concede that the general attractiveness rating used means they know little of the sexual competitiveness of the DT personality, but they still try to imply that they do,

…we are not asserting that female respondents who rated the DT character as attractive would necessarily be willing to engage in sex with them. However, our findings do indicate that the DT personality is attractive to our participants. This in turn supports previous work that has suggested DT men are more sexually successful.

The “previous work” being based on self-reports from men who by definition are boastful and self-enhancing. That’s somewhat like two drunks leaning on each other to stay upright. Then, in a paper only a month later, the Carter reconsiders the whole idea of DT as an evolved strategy for male short-term mating when he found that women with subclinical DT traits are about as common as men,

We propose that focus on DT as a male adaptation to short-term mating has been overstated and that men’s greater preference for casual sexual encounters is not explained by DT traits.

To conclude, all research I’ve found on this fails to support the hypothesis that women like bad boys, be it long-term or short-term. It echoes earlier research showing extraversion and emotional stability to be attractive traits but does nothing to establish an effect of the Dark Triad beyond those correlates.

The Sexiest Men Alive

Women only like him because they can sense that his a complete jerk?

Henry Cavill. Women only like him because they can sense that his a complete jerk.

Still, science is rarely perfect, especially not soft science. Sometimes constructs and study designs can fail to model what takes place in the real world. Perhaps we are better off looking to popular culture for answers? It’s not controversial to say that we live in sexualized celebrity culture. It’s not uncommon for pop culture media to rate celebrities on how attractive or sexy they are. I’ve looked at some of these lists of highly desired men to see if they can shed some light on this question. First off, here is Glamour Magazine (UK) reader’s vote on sexiest men 2013 (95K voters),

  1. Henry Cavill
  2. Robert Pattinson
  3. Liam Hemsworth
  4. Tom Hiddleston
  5. Benedict Cumberbatch
  6. Harry Styles
  7. Chris Hemsworth
  8. Idris Elba
  9. Jamie Campbell Bower
  10. Justin Bieber

As an, admittedly limited, bad boy indicator, I looked at the “controversy”, “personal life”, and “public image” sections on Wikipedia entries for these boys and men. I could not find dirt on anyone but Justin Bieber, but as his stardom preceded his controversial behavior that’s irrelevant. If anything his star appears to have waned as his bad boy image emerged.

Next, People Magazine’s Sexiest Man Alive 2013, not voted but with 46 million readers and ad revenues of around a billion dollars yearly, they probably know something about what celeb starved readers like,

  1. Adam Levine
  2. Idris Elba
  3. Luke Bryan
  4. Jimmy Fallon
  5. Bruno Mars
  6. Jonathan and Drew Scott (identical twins)
  7. Justin Timberlake
  8. Chris Pine
  9. Pharrell Williams
  10. Ronan Farrow

Same story here. Adam Levine has had some drug problems in his adolescence but is now sober and a successful musician and entrepreneur who is also committed to helping children with ADHD. Chris Pine has one DUI but it’s from this year so as with Bieber it precedes his celebrity status. There may of course still be some controversy to be found if you dig a little deeper, but digging deep is not what celebrity culture is about. If the popularity of these men depended on a bad boy image you wouldn’t have to look further than Wikipedia to find evidence of it.

They may seem dangerous but girls love them ; )

One Direction. They may seem dangerous but girls love them.

Then you have the boy bands – intentionally designed to appeal to girls and younger women. This genre should be overflowing with bad boys. But has there ever been a boy band of bad boys? Or even a non-cute boy band?

If girls and women really like their jerks so much, why then would they favor men who don’t have a hint of a mean streak, when voting in polls, buying music, watching movies or attending concerts? To convey a socially acceptable persona? We’re talking about teenage girls here. It seems infinitely more plausible to assume that they spend time and money on the men they do find attractive – and they’re not Dark Triad. They appear to share the DTs extraversion and emotional stability, but there is just nothing dark per se about them.

So again, we find no support for the theory. And yet people seem convinced of the bad boy allure. It would seem the real mystery then is not why chicks dig jerks, but why this belief is so popular despite of the overwhelming lack of empirical evidence, or evidence to the contrary.

Male Hypervigilance

I haven’t found any research on this particular issue, but I have found some stuff on related ideas that may explain this belief. First, Dark Triad men exist and pursuit short-term sexual relationships. To say, as Carter did in his retraction, “men’s greater preference for casual sexual encounters is not explained by DT traits” is going too far in the other direction. By all accounts these men are players, just not all that successful at what they do. But even so, they constitute a danger to other men, and men who disregard this danger may have been weeded out by natural selection. Because from an evolutionary perspective, the worst thing you can do, short of getting yourself killed, is to raise someone else’s children. Still, this doesn’t answer why men overestimate the bad boys’ attraction on women. Wouldn’t a realistic assessment lead to the highest fitness? Not necessarily. Evolutionary theorists have a concept called agent detection, according to the Wikipedia entry defined as,

“…the inclination for animals and humans to presume the purposeful intervention of a sentient or intelligent agent in situations that may or may not involve one.”

Assuming there is someone out there, an enemy, a tiger or some other danger will be a relatively little cost compared to the risk of assuming it was just the wind. Like a motion detector that will go off regardless of whether it’s a cat or a burglar on your lawn. Better safe than sorry, at least when the cost of being sorry is sufficiently high.

This agent detection mechanism should apply to any situation in which hypervigilance can pay off due to potentially high costs. And raising another man’s child will drastically reduce your fitness, so being overly suspicious may well pay off.

A related topic that lends some support to this theory is that of paternity fraud. According to an article in Discover Magazine by biologist and science writer Razib Khan, estimates of false paternity among the public is very high, ranging from 10 to 30 percent. He contrasts this with a survey of the research in this field which has paternity fraud at 2-3 percent among men with relatively strong paternity confidence (and even lower among Northwest Europeans and Jews). For men with lower confidence who have decided to take a test to settle the issue, which must be a pretty strong level of suspicion, a full 70 percent are still proven wrong.

As Khan argues, this may relate to agent detection, the logic of erring on the side of caution when a lot is at stake. It seems very likely that the chicks-dig-jerks idea is part of this hypervigilance since paternity uncertainty means worrying some smug bastard had his way with your woman, and unless she’s a complete whore it must be the man who made it happen, someone who is actively pursuing short-term sex, who sees himself as a womanizer and brags about it. Someone like a Dark Triad man. The hypervigilance will then be post-hoc rationalized as being due to the fact that chicks dig jerks.

Well, that’s my theory any way, and sad if true, since at least some of these men think of their delusion as an almost heroic form of realism. Unlike all the saps and phonies (the betas in manosphere parlance) who buy the sugar-coated, fluffy crap about human nature, they believe they alone see things the way they really are. Is there a way to snap out of that? I’m not so sure.

Book Review: The Ten Thousand Year Explosion (2009) by Greg Cochran and Henry Harpending

October 27, 2014


I have a feeling most people don’t read reviews, but with some books I still think it’s worth making a little noise. Books like The Blank Slate by Steven Pinker, The Nurture Assumption by Judith Rich Harris, and The Righteous Mind by Jonathan Haidt. And now this one, so yes, it’s kind of a big deal. Many readers of this blog are no doubt already familiar with it, but since some probably aren’t, and it has been ignored by most of the media, I feel I should throw my two cents in.

The Persistence of Blank Slatism

The authors, physicist Greg Cochran and anthropologist Henry Harpending, challenge a common view among both the public and in Academia that evolution ended some 50 thousand years ago after the exodus out of Africa, or that it’s too slow to have any meaningful impact on humans within that time period. For that reason we must, they claim, be the same biological creatures as we were back then. As a consequence of this view, the cultural diversity that we see today and throughout history must also be unrelated to biology. They quote the late biologist and popular science writer Stephen Jay Gould who sums up (and embraces) this opinion,

“Everything we call culture and civilization we’ve built with the same body and brain.”

Most of his readers gladly accept this as the truth. It is after all the Blank Slate that has dominated Western thought on human nature for the last 400 years or so that claims we are all built of the same stuff, we all share an incredible ability to change, improve, and evolve. Steven Pinker did some damage to this idea but most people who have read him seem to have landed in a half slatism, admitting they were wrong but only half wrong. In psychology, this is known as anchoring: people don’t change opinion to fit the evidence but meet the evidence half way. And ironically you can be as anchored in thinking you’re a free spirit as in any other point of view.

But “the same body”? Are there Japanese people who can be mistaken for Scandinavians? Are there Peruvians who could pass themselves off as Nigerians?

More likely, as the authors argue, is that when leaving Africa humanity spread to various different environments, each with its own unique selective pressures. East Asians (to be) who passed through the extremely cold climate of central and northern Asia got shorter extremities. They and northern Europeans became paler as they were less exposed to the sun and they lost the ability to retain salt while sweating as they sweated less in their new environments. The people of the Andes and Himalayas became adapted to high altitude, and so on.

In short, our bodies are not the same. There are plenty of differences that are obvious adaptations to new environments giving rise to slightly different variants of Homo sapiens. And there are no supernatural elves guarding the blood-brain barrier either; the brain, for all its sophistication and complexity, is still part of our body, so anyone seeking the truth about human nature must at least entertain the possibility that evolution may have produced mental, biologically based group differences.

The Upper Paleolithic Revolution

There is little doubt that something big happened around 45 thousand years ago. At this time all sorts of innovations pop up – bow and arrow, fishnet and fishhook, cooking, rope, basket, textiles. Other novelties such as art, music, trade, and ritual burials indicate that there was a sudden and fundamental shift in human thinking, away from the day-by-day living of roaming bands, towards a more reflective, planned and organized way of life.

This abrupt change is hard to understand in terms of natural selection as there is very little time and no signs of strong selective pressures. In fact it seems so hard to understand it that many scholars deny it altogether. Instead, they argue for a gradual development by showing cultural artifacts that predates that of the Great Leap Forward, as it’s sometimes referred to. But I think it’s clear that they make their case more with words than with actual evidence. The extent to which they ascribe ingenuity and artistic qualities into the artifacts predating the Great Leap is similar to how some mothers will praise the scribblings of their children. As geographer and science writer Jared Diamond pointed out in another interesting book, gradualists have a tendency to give fancy names to early primitive tools as a way of creating an appearance of continuity,

Early stone tools vary in size and shape, and archaeologists have used those differences to give the tools different names, such as ‘hand-axe’, ‘chopper’, and ‘cleaver’. These names conceal the fact that none of those early tools had a sufficiently consistent or distinctive shape to suggest any specific function, as do the obvious needles and spear-points left by the much later Cro-Magnons. Wear-marks on the tools show that they were variously used to cut meat, bone, hides, wood, and non-woody parts of plants, but any size or shape of tool seems to have been used to cut any of those things, and the tool names applied by archaeologists may be little more than arbitrary divisions of a continuum of stone forms.

So most likely there was a Big Leap, and a corresponding biological leap that enabled it. But what kind of biological change could have such a dramatic effect?

The Neanderthal Within

As I said earlier, natural selection is not a likely candidate. The change is just too large and rapid, even if the new environments presented strong selective pressures and humans had lots of pre-existing genetic variation to work with. And clearly the new environment did not set the Neanderthals already living there on a highway to any kind of cultural revolution.

Instead the authors suggest that the change was caused by interbreeding between the Homo sapiens leaving Africa and the Neanderthals who lived in Europe and Asia. These two species split up some half a million years ago and Cochran & Harpending point out that no primate species have split completely in such a short time. And as human population genetics shows, people who live next to each other will inevitably mix to some extent. So common sense dictates that interbreeding was very likely.

This way Homo sapiens could have picked up a number of advantageous gene variants almost instantly. Most likely some of these variants relate to language skills (it’s very hard to think of something like trade without some kind of language). One such candidate gene is the FOXP2 that involved in speech, another suggested by the authors is MCPH1 that regulates brain size, as these both have new versions that roughly fit the time when Homo sapiens met Neanderthals and the cultural explosion that followed.

Since this book was written in 2009, you may wonder how well the theory holds up in view of current evidence. Well, recently gradualists have seized on a piece of depictive cave painting in Sulawesi, Indonesia, estimated to be around 35 thousand years old. They argue that this find somehow makes their case, but I honestly can’t see how it would do that. It leaves plenty of time for Homo sapiens to leave Africa, pick up the crucial Neanderthal gene variants in the Middle East or Europe and then migrate to Southeast Asia. And fact remains that advanced artifacts, such as depictive paintings, are still only found in times and places where people are likely to have Neanderthal admixture.

Meanwhile the evidence for interbreeding, doubted by gradualists like anthropologist Sally McBrearty, is now pretty solid. Recent studies also indicate that the authors were slightly off regarding the time line as it appears that interbreeding happened just before the window of opportunity would have closed. The FOXP2 is also ruled out as a Neanderthal contribution to contemporary humans. But the main point is that it did happen and that and non-Africans (Neanderthals were never in Africa) worldwide now have a few percent Neanderthal DNA as a consequence. So thus far, their theory is holding up pretty well.


This, however, isn’t even the main point of the book. The Upper Paleolithic Revolution is just the starting point of a new chapter in human evolution. Cochran & Harpending argue that the cultural innovations that emerged around 50 thousand years ago created selective pressures that were much stronger than those already in place so that we evolved faster than before. Sure, innovations had no patents back then so they were accessible for all. But not everyone was equally skilled at using them. If you’re good with a bow and arrow you’ll shoot the game from a safe distance, if you’re less skilled you’ll have to get closer and take the higher risk. But that would still be preferable to getting up close and bludgeoning it to death with a club, which seems to have been the Neanderthal way.

Language, as the authors point out, may well be the most important cultural innovation of them all, and no doubt one creating an enormous selective pressure. With good language skill you can excel at trade, you can convince, seduce, and deceive as well as detect deception. You can make detailed plans together with others. All of this confers obvious fitness – in proportion to your skill level. And thus far we don’t know of any skills that aren’t highly heritable. So if you agree that language and other cultural innovations have been of great importance to our success and survival in our recent past, then you must also agree that the genes behind the corresponding skills would have been selected for in proportion to that success. These skills then changed how we think which must have led to further innovations, “Men made better tools and then, in turn, were reshaped by those tools over many generations.” This of course must have been going on since the dawn of humanity. But with the Upper Paleolithic explosion the process shifted gears.

Genetic Evidence

As plausible and common sense as this sounds, the authors also offer more direct evidence of recent selection. For instance that which is based on a phenomenon called recombination. Thing is, we don’t inherit single genes, instead chromosomes from our parents are cut into 2-4 pieces and half of these pieces from each parent are then put together – recombined – to make our own chromosomes. As the cuts are few and the chromosomes contain enormous stretches of DNA, it’s unlikely that a cut will be anywhere near a single gene. So when a favorable mutation starts spreading through a population its closest neighbors usually tag along, like the entourage of a rising star. Together they make up a characteristic pattern called a haplotype. The more advantageous the mutation is the more common the haplotype will become. But with every generation that passes the cuts in the chromosomes will reduce the length of the haplotype so that fewer and fewer genes around the mutation will be shared in the population. So while fitness is indicated by how common the haplotype is, age is indicated by its length (the longer, the younger).

This means that common and long haplotypes can only exist if there is still strong and recent selection. This is for instance the case with lactose tolerance among people of European ancestry, which is only a few thousand years old. But according to the authors, recent studies show plenty of long and young haplotypes, some of which have reached 100 percent frequency in their populations. This can only mean that there is both strong and recent selection on a large scale. So evolution is still going strong

They offer other types of evidence too, supporting the idea that the rate of evolution is accelerating, but this is the part I found most convincing.


Unlike the Upper Paleolithic Revolution, agriculture was a single innovation that emerged some 12 thousand years ago. But its impact on the course of evolution was probably at least as big. It increased the world population from ca 6 million to 600 million by the time of Christ. As mutations are proportional to the size of the population this means a hundred fold increase of new mutations to speed up evolution even more. But like any innovation promoting fitness it also created a selective pressure benefitting the most skilled farmers.

But it also meant a new diet, based heavily on grain. While more people could be fed this way, the diet itself was low on protein and other nutrients. Average height dropped almost five inches with the introduction of agriculture. This meant that any mutations that would somehow increase access to protein would be selected for as was the case with those rendering owners lactose tolerance. The mutations that enabled adults to consume dairy food spread like wildfire among early farmers. This is a very compelling piece of evidence of the process of gene-culture coevolution that the authors mean is the force that has created our human nature. Culture (in this case agriculture) created a selective pressure for lactose tolerance which then in turn affected our culture as our diet and food production changed. And all this in just a few thousand years. Do we have any particular reason to assume that this process wouldn’t affect our culture and our behavior in other aspects?

Personality: The Rise of the Nerds

I ask this because just like the Upper Paleolithic innovations made certain skills important so did agriculture. The former most likely brought complex speech and the ability to deceive. Before that life was probably no picnic, but there wasn’t much room for Dark Triad personality traits. Language, however, must have created a huge selective pressure for such traits. And with agriculture came new traits, since traits tend to correspond to skills. The hunter-gatherers didn’t need to make plans; they roamed, and they may have memorized certain places and routes where food was plentiful or where they could find shelter. As the authors point out, instant gratification would not be a problematic trait under those circumstances. But the farmer who ate just a little of the grain needed for next year’s sowing may well have sealed his and his family’s fate that way, especially a northern farmer.

Farming changed the whole way of life. It required making plans, collecting and evaluating information, and thinking ahead – sometimes years ahead. It required intelligence, true, but also a kind of personality captured by Big Five Conscientiousness, MBTI Thinking and Judgment, or the Cerebral factor of interests isolated by psychologist Peter Rentfrow and colleagues. These all refer to being rational, deliberate and careful. While this sounds like being intelligent none of these measures correlate with actual intelligence. It’s more similar to being nerdy. This cerebral/nerdy trait is most likely an even newer aspect of human personality than the Dark Triad.

What about the Pastoralists?

This begs the question of why people in the Middle East, who the authors argue should be the most adapted to agriculture, can be so unnerdy? They mention resistance to type 2 diabetes as an example of an adaptation to agriculture (a larger intake of carbs), but people in the Middle East have the highest prevalence of type 2 diabetes in the world. There is a possible explanation for this in the form of nomadic pastoralism. This culture emerged around 3000 years ago in the Middle East and remains strong right up to the modern era. So their experience of agriculture is interrupted and mixed with this other culture and corresponding diet, richer in meat. And since agriculture has been an accelerating process, cutting off 3000 years at the end means a whole lot more than at the beginning.

But pastoralism is more than an end of agriculture. It’s a cultural innovation with its own pressures, taking people in that culture down a different evolutionary path. This path leads to inbreeding, clannishness, honor culture and a warrior-like lifestyle. This is where I feel this book is lacking a conspicuous piece of the puzzle. It focuses too much on agriculture and gives the reader the impression that differences between populations are mainly about how long they’ve been farmers. They do mention it but mainly in the discussion of how early Indo-Europeans conquered the steppe with the edge of lactose tolerance. But if human nature has been shaped varying selective pressures of agriculture then the same should hold for pastoralists. (This type of human is described in some detail by blogger HBD Chick.)

Ashkenazi Intelligence

As a final example of just how fast the wheels of evolution are spinning, the authors present the rise of Ashkenazi intelligence. This would be a significant change in less than a millennia, which may be hard to believe in. But although speculative, it’s not a matter of belief, but of evidence and plausibility.

The Ashkenazi has existed as a distinct group of Jews since medieval times, but according to the authors their intellectual prominence is as late as the 1800s. Today their average IQ is estimated at 112-115. They have won more than 25 percent of all Nobel prices but make up only 0.17 percent of the world’s population. That is pretty mind-blowing. So how did it happen?

The cause, Cochran & Harpending suggest, is a well-known historical fact that most people simply don’t think of as relating to the theory of evolution,

“When persecution became a serious problem and the security required for long-distance travel no longer existed, the Ashkenazim increasingly specialized in one occupation, finance,

left open to them because of the Christian prohibition of usury. The majority of the Ashkenazim seem to have been moneylenders by 1100, and this pattern continued for several centuries. Such occupations (trade and finance) had high IQ demands, and we know of no other population that had such a large fraction of cognitively demanding jobs for an extended period.”

So they were effectively forced into high IQ professions and as success translated to more children this constituted a very strong and unique selective pressure that increased their intelligence. This sounds plausible, but while we know of their later achievements we don’t have any way to estimate their intelligence at the beginning of this period. The fact that they were sought after in the finance sector must mean that they had some smarts right from the start. As blogger Jewamongyou points out, in his overall positive review, religion may be an overlooked selective pressure, “It was specifically religious scholarship that made a man coveted as a husband.”

I have no idea of just how sexy Talmudic analysis was back then and to what extent those who excelled at it could extract resources to afford more children than others. But if this was the case then it certainly changes things a bit. It would weaken the case for superfast evolution, but the authors would still have a case for very fast ditto. How so?

Well, Ashkenazi Jews are a genetically distinct group with a number of serious genetic diseases. The popular explanation for this is that they at some point passed a bottleneck, a point when the population was so small that single individuals would leave their genetic mark on future generations. This has happened before but in this case the gene variants behind these diseases cluster together in regard to very specific functions of the brain and nervous system, DNA repair etc. A bottleneck would be random – no clusters.

Instead these clusters suggest that selection for something having to do with the brain – something that improves fitness – has taken place. And it would be recent selection as the genetic diseases are caused by homozygosity in these genes. Because in the long run adaptive genes with harmful side effects will be replaced by less harmful ones. So like haplotypes, harmfulness is another way of dating adaptations. And these diseases like for instance Tay-Sachs are among the worst imaginable.

So be it finance skills or perhaps religious fervor (that would surely give Richard Dawkins a stroke), there is still a case for some recent selection relating to intelligence.


Like I said in the beginning of this review, I think this book is among the top science books of recent years. It replaces the highly popular nonsense idea of halted evolution with a plausible theory of accelerating evolution. It provides a theory of how human nature has been shaped and differentiated into genetically distinct groups, not just by the physical environment, but increasingly by the social environment that various cultures represent, the most important factor being agriculture (or lack thereof). I still miss the pastoralist/clannish branch but maybe that will be in the next edition.

It would be easy to dismiss it had it not been so plausible and backed up by hard evidence. So the natural reaction from science journalists, pundits etc, the majority of whom still feel Stephen Jay Gould view is valid, is to ignore this book. Economist Tyler Cowen (who also doubted Homo sapiens interbreeding with Neanderthals despite of the common sense appeal of the idea) wrote a sweeping 14-line review, snubbing it without addressing anything specific, hardly more than a hit-and-run. One professor of biochemistry by the name of Larry Moran even tried to question the veracity of the Gould quote above, presumably hoping that fact checking is now a thing of the past. (Anthropologist John Hawks set him straight on that one).

I think this silence and these inferior attempts at dismissal speak volumes by themselves. If critics really had a good argument against Cochran & Harpending then surely they would use it. Given how the academic community tends to react to theories about heritability of intelligence and personality trait, innate group differences etc, I think they would use it much like a Neanderthal would use a club to bludgeon someone from an enemy tribe to death with. But don’t take my or anyone else’s word for it. It’s a short book, an easy read, and it only costs 10 dollars. If you’re a truly intellectually curious person, chances are you’ll get a good buzz from it. I certainly did.


The Nurture Enigma – How Does the Environment Influence Human Nature?

January 21, 2014
Ms Smarty-Pants.

Ms Smarty-Pants

Historical Background

As some of you are well aware, a predominant idea among intellectuals has been that human nature is shaped by the environment, commonly known as the Tabula Rasa or in English, the Blank Slate. This has been the cornerstone of the Enlightenment, the political and philosophical movement of that grew out of late 1600s England and spread throughout the world (although mainly to countries of Northwest European origin). It was an idea that justified social reforms that greatly improved life for most people who were affected by them.

The Tabula reigned pretty much until 1975 when biologist E. O. Wilson wrote Sociobiology, a book that attempted to use evolution to explain not only animal but also human social behavior. Although this book shook things up in Academia it didn’t make that much impact elsewhere. It wasn’t until the 1980s that the reaction against the Blank Slate began to get serious. At this point in time people in the field of behavioural genetics conducted studies on the heritability of things like personality and intelligence that were so extensive and of such quality that they simply couldn’t be ignored. And they showed substantial heritabilities of not just some traits but all of them, something that still holds today. There were some die hard blank slatists, like biologist Stephen Jay Gould, who persisted but most of the resistance to the idea of an inheritable human nature had waned by the mid 1990s (at least that’s my impression).

So the general idea of all nurture and no nature was losing the battle but the vast majority of people were still unaware of this and continued their lives as if nothing had changed – carefully rearing their children during their “formative years” according to “expert” advice, and feeling great when they turned out good, and feeling guilty when they didn’t.  Then in 1998, a text book writer named Judith Rich Harris wrote a book called The Nurture Assumption, summarizing and popularizing the findings of behavioural geneticists, focusing especially on the implications for child development. This was followed in 2002 by psychologist Steven Pinker’s book The Blank Slate, a broad exposé of the whole nature-nurture issue that in its informative and entertaining style became popular in wider circles. People still talk of the formative years even today (I just got a comment from one of them), but by now the tide has irreversibly shifted.

The Post-Slate Situation

So, what does the “new” research from the 1980s, that is now finally beginning to reach public awareness, tell us about human nature? The most obvious part is that nature is a major factor. This is typically summed up in textbooks in the 50/50 rule, claiming that genes and environment can explain about half of the variance each of things like intelligence, personality, psychopathology etc. Which is easy to remember – but also incorrect. This is due to the fact that there is something called measurement error. Most studies are done in a way that doesn’t distinguish this error from the environmental factor. So it’s 50 percent nature and 50 percent environment plus measurement error. Studies that have managed to minimize measurement error typically yield heritabilities for personality traits and similar characteristics around 70 percent. You also have the fact that some of the traits linked to the most important life outcomes, like intelligence and impulsiveness, have even higher heritabilities, around 0.75-0.80.

Equally important – and especially problematic for the adherents of Enlightenment –  is the distinction between shared environment and non-shared environment. It’s the shared environment – family, school, neighbourhood etc – that would lend itself to social reforms. But the research has consistently shown that this factor is very small, often close to zero. As behavioural geneticist Robert Plomin says,

‘Nurture’ in the nature–nurture debate was implicitly taken to mean shared environment because from Freud onwards, theories of socialization had assumed that children’s environments are doled out on a family-by-family basis.

So while there is still a fair amount of environmental influence, it’s not coming from parents, schools, teachers etc. Some people will never accept this; they are too stuck in their political views, they like to blame their parents for how they turned out or take credit for the success of their children. But rational and intellectually honest people will be forced to accept it.

Judith Rich Harris and the Enigma of Non-Shared Environment

But this still leaves us with a substantial environmental influence of the non-shared variety, the unique experiences of the individual, that undeniably affects our personality and intelligence. So what experiences are we talking about?

Oddly enough, 30 years after behavioural geneticists uncovered the importance of non-shared environment, we still don’t know anything about the nature of this influence. This great mystery that goes right to the heart of human nature seems to be uninteresting to both psychologists and the media. Possibly because of the political implications but it might be that they simply lack ideas or intellectual curiosity. After all, personality psychologists – 95 percent of whom identify as liberal – do not praise the Big Five model for all the theories it has generated but for all the consensus it has achieved. Yay…

But one woman, the above mentioned Judith Rich Harris, is actively searching for answers. In a chapter in the anthology The Evolution of Personality and Individual Differences by psychologists David Buss and Patricia Hawley, she reviews the evidence, the old theories and proposes a new one that could explain the nature of the non-shared environmental influence.

Gene-Environment Interactions

This is not to say that she is the first to have attempted this. Some have claimed that parents, school and all that may still be important because of gene-environment interactions: the fact that the same environmental factor will affect two persons differently because of their different DNA. This would mean that the environment believed to be shared is really unique and non-shared and possibly very important.

While gene-environment interactions do occur, Harris argues that it’s highly unlikely for these interactions to cancel each other out. Would an overbearing teacher make one child anxious but the other calm and confident? Even if some children would become angry by such a teacher this would not be the opposite of anxious but rather two expressions of neuroticism. Apart from being implausible, Harris also points to the fact that interactions seem to be rare and most of the documented cases involve sensitivities in which people have the same reactions in varying degrees, not opposite reactions that would cancel each other out.

Even more damning to this theory is the research on identical twins. If things like family was in fact unique and non-shared due to gene-environment interaction for siblings it could not be that for the twins since they have identical DNAs so no interactions are possible. This would mean that parents, school etc would have a profound effect on all people with the exception of identical twins for whom it would mean little or nothing, which would make them fundamentally different from the rest of us. At the same time identical twins have the same size of shared and non-shared environment influence as everyone else. So even though it would be made up of completely different experiences it would still by some happy accident add up to exactly the same size. It just doesn’t make much sense.

Family Interactions

Another couple of theories that both try to save the idea of family as an important influence on human nature, are those of differential parental treatment and birth order effects. While it has been found that parents do treat their children differentially, Harris mentions research on this that showed no effect of this on the children. Instead it suggested that parents do this as a response to the children’s varying behavior. Which sounds very plausible: you would not expect a parent to lose his or her temper as often with a quiet and conscientious child as with an impulsive and emotionally unstable one.

Research has also failed to provide support for any effects from sibling interactions, a very popular theory. Sibling rivalry is something most people can recall from their childhood. It may seem only natural that all that bickering would have some impact. But to date, there is no evidence of that. Identical twins again provide further evidence to the contrary, since they have been found to compete less with each other (as they should according to the laws of evolution). This would mean that the sibling interaction effect would be smaller on them and we again end up with the idea that identical twins have a different shared environment than the rest of us but that it serendipitously adds up to the exact same size.

The Three Systems Theory

Instead of these half-hearted attempts at rescuing any possible remains of the Blank Slate, Harris proposes a different theory based on evolutionary psychology and especially on the observation that traits or mechanisms tend to evolve to solve specific problems and that they for this reason often are largely independent of each other.  So, what problems and what mechanisms?

Well, we know that personality is more malleable in childhood than in adulthood. This is most likely because the brain’s plasticity gradually decreases over the life span. So the environment should exert most of its influence during childhood. This means that we should look for basic adaptive problems that children face. Harris identifies three such problems: how to form personal relationships, how to fit in among your peers, and how to compete among your peers. To solve these problems she hypothesizes that the brain has evolved three mechanisms or systems which she calls the Relationship System (RS), the Socialization System (SS), and the Status System (STS).

The RS is basically an ever-growing database of information on people along with judgments of them based on that data. Since these judgments are used to relate to people they tend to be emotional – who we love, hate, fear, pity and so on. Another characteristic is that the data collected is consciously retrievable. The RS is the base of gossip; we talk about people we have stored information on and compare notes. Although in the modern world this is often done about celebrities that aren’t socially relevant to us.

The SS also collects data but on social categories – male, female, adult, child, rich, poor etc. This is essential information if you want to fit in because you need to know where to fit in – which social categories apply to you. Unlike the RS that looks at personal experiences of specific individuals, the SS generalizes about groups, stereotypes you might say. It’s the basis of our ingroup/outgroup distinctions, according to Harris. But when did we learn about these categories? At no particular time, it just builds up gradually. So unlike the information in the RS, there is no consciously retrievable memory of it.

Finally, we have the STS which collects information about where we stand in comparison to other people in our social category – because that’s where the competition takes place. The reason for keeping track of all the possible status hierarchies – being funny, smart, tough etc – is that it enables the child to find an optimal competitive strategy. So this system looks for things like respect, appreciation and recognition.

So which of these systems is the most likely mechanism by which non-shared environment can influence personality? Although Harris doesn’t say much about why the RS couldn’t do this, we already know that some central relationships in a child’s life are those with family members – which is shared environment and thus of little importance. Still, close friends seems like a possible candidate here… She points out that the least likely mechanism would be the SS, since this is a process by which the social environment (peers) reduce variance in personality as it makes children conform to the people in their social categories. But the STS looks very promising. When a child looks for an optimal strategy for competition, it isn’t looking to conform but to stand out. And if one niche is taken it will have to look for other venues. Like if you’re a big boy who is moderately funny in a peer group of plenty of really big guys but no one who can tell a joke, you may go against your genetic disposition and become the comedian rather than to assert yourself physically.


Now that sounds like a plausible theory, but is there any evidence?

Harris agrees that her theory needs to be tested but she does have some evidence too. She mentions the fact that men who were tall as boys grow up to be more assertive and confident as adults. That height in adolescence predicts salary better than height in adulthood. Although she admits that the same thing that makes a person grow fast (androgens) may also be causing their assertiveness. To get around this Harris suggests that we look at relative age within peer groups. One important peer group is that of classmates in school, in which children can differ in age up to a year. This makes for differences in size and maturity that are unrelated to hormones or other biological factors. This relative age effect can be seen in sports where the older boys in groups of selection are picked up by better teams. This may seem stupid if all you do is select players who happen to be older than their peers. But what if being bigger also give them confidence that in turn make them better players?

A study by Dr Chris J Gee at the University of Toronto, published in the International Journal of Coaching Science gives some support for this idea. Gee has followed promising young hockey players over 15 years in order to see if personality can predict success in the sport. According to the study a composite measure of the typical traits thought to be linked to success – self-confidence, need for achievement, competitiveness etc – did in fact predict success. And in regard to the relative age effect common in drafting, Gee writes,

Interestingly, when height and weight (both commonly cited anthropometric indices used when scouting amateur hockey players) were entered into each of the previously mentioned regression models, they failed to significantly increase the amount of variance accounted for.

This strongly suggests that coaches pick the boys who are oldest in their age group, not because they are bigger or have more androgens or something like that, but because they have certain personality traits associated with athletic success. How did they get those traits if all that distinguishes them from other boys is that they happened to be born earlier? It seems to me that Harris’ theory fit these data very well: these boys became confident and assertive through their social environment of peers who couldn’t push them around. This put them on the track to athletic careers, while others who might have been of average size for their age but the youngest in their age group turned to comedy or some other way of becoming popular and getting status.

I think Harris may be on to something.

Book Review: Why Evolution Is True (2009) by Jerry Coyne

October 18, 2013


I read this book just to get an introduction before going to the heavier stuff. Not that I’m completely ignorant on the subject but I often find that going back to the basics is the best way to re-kindle and interest and as a launch pad for the heavier literature. The obvious choice for a non-expert would probably be Richard Dawkins, but I find his style a bit pompous; he sounds too much like the character Buzz Killington in Family Guy. So I settled for biologist and evolutionist zealot Jerry Coyne instead. He has a clear and simple albeit impersonal style like so many writers in Academia. Unlike many other biologists, he focuses on the theory and doesn’t get bogged down in a myriad of empirical facts, something that has always turned me away from reading books on biology; maybe it’s an aspergery trait of biologists, I don’t know.


He starts off with a presentation of the basic concepts of the theory, like natural selection, how gene variants in a population will become more or less frequent depending on whether they will promote survival and reproduction in a species. Then there is the less natural selection that is due to the fact that most species reproduce by sex rather than by cloning themselves. This means that we only pass on some gene variants to our offspring. Gene variants that aren’t good or bad can then become more or less common in a species just by random recombination, so-called genetic drift. It could also happen when a species dwindles to a very few individuals (called a bottleneck). If these individuals all happen to have pointy ears and this trait is neutral, then pointy ears it is. This random effect is not a big factor but it does happen.


The other big thing is speciation: how every species ends either in extinction or by splitting into two new species. This means that the ancestral tree of all species is binary, and full of dead ends as most species become extinct without leaving any descendants. Speciation usually happens as populations of the same species are separated in different environments. A new environment will make new traits more adaptive, that is leading to survival and reproduction. And so the gene variants that cause these traits will become more common. This means that the populations become genetically less related. At some point they can’t interbreed anymore and the species has split. Unless Homo sapiens becomes extinct, we too will split eventually. I bet that will be awkward…


The evidence for evolution can be found in many places. In spite of modern DNA technique, fossils remain an important clue to how life has evolved. We can date fossil by looking at what layer of rock it is located in, or by radioactive material that breaks down at a certain pace after the rock formed. Another dating method is based on the fact that the Earth’s rotation is slowing down so that days are getting longer and years are getting shorter – 380 million years ago, a year had 396 days and a day had 22 hours. Some organisms have growth markers for both day and year that are preserved in their fossil and can be dated this way.

What the fossil records tell us is that life has evolved, become more advanced and better adapted to various environments. When we go backwards in time we can find how tetrapods evolved into reptiles that evolved into birds and mammals. And all the fossils can be dated to the time period when they are supposed to be if evolution took place. That’s pretty hard evidence.

In a way art is like fossil - something alive in the mind of the artist that has been petrified and frozen in time. Art by Jenny Edlund. For more of her work just click the image.

In a way art is like fossil – something alive in the mind of the artist that has been petrified and frozen in time. Art by Jenny Edlund. For more of her work just click the image.

We can also find evidence in the form of vestiges, like the wings of ostriches. Both DNA and fossil records show that they descended (hehe) from flying birds. So at some point flying was not beneficial anymore and they started to evolve new traits. But wings can’t just disappear from one generation to the next, so in the case of the ostrich they represent a transition between the flying wing and whatever trait they will evolve into in the flightless existence. Why did it happen? One clue is that they are common on remote islands with few reptiles and mammals that could prey on them.

Or we have the hind legs of whales, small bones no longer connected to the rest of the skeleton, encapsulated in their bodies. They make no sense at all unless whales descend from land-living animals. Same goes for dolphins that have inactive olfactory receptors. Or our own genes for tails, also inactivated in most of us. And so on. Overall, Coyne presents this evidence well and makes a good case.

The Mystery of Sexual Selection

But when it comes to sexual selection, in which choice of mate decides the reproductive success of the individual, he fails to deliver a clear and reasonable explanation. Even Darwin had problems with this phenomenon. This type of selection is partly about male competition, the strongest walrus will knock out his competitors and mate with the females. That’s easy to understand because strength and endurance required to win these battles are heritable qualities that will then be passed on to the next generation. But in some cases, like peacocks, the males just show off gaudy traits like bright colors and large tail feathers and such. And for some reason the gaudiest win.

It seems that females (and in some species males) will choose whatever is novel and intense. You can glue some random blingy stuff on males and they will be transformed into desirable alphas. This makes less sense because unlike an alpha walrus who was selected for traits that enable him to search for food or fight off other animals, the gaudy traits are useless, even harmful as they reduce the animals mobility and attract predators. Or are they?

This, apparently, is what a real male looks like.

This, apparently, is what a real male looks like.

Coyne explains this as having to do with the fact that the sexes have different numbers and sizes of their gametes (eggs and sperm). But why did sexual reproduction become so common in the first place? The author says this is unclear. And why two sexes rather than three or five? And why the asymmetry of the gametes? Coyne says these are “messy” issues and just states these things as facts the reader will simply have to accept. I guess that saved him a lot of hard work, but it does nothing for the reader. But since the number of sexes and the asymmetry of gametes are facts, let’s move on and see if Coyne can explain sexual selection – and especially the weird gaudy traits that even Darwin was worried about.

Since the number of gametes is higher for males it means they can sire more offspring. The author exemplifies with the male record holder, a Moroccan emperor during the 1700s who had around 1000 children as opposed the female record holder, a Russian women (also living in the 1700s), who had 69 children. However, he fails to mention that women have hundreds of thousands of eggs so that doesn’t appear to be the limiting factor. It seems to me that the length of the pregnancy would be a more obvious reason why women can’t have a thousand children. He does mention that females have a larger investment in this way too but how does it relate to gametes?

But again, it is a fact that females are usually more invested and this means they have to be more picky regarding who they will mate with. But how do we go from that to the preference for gaudy traits? This is how Coyne explains it,

Males must compete to fertilize a limited number of eggs. That’s why we see the “law of battle”: the direct competition between males to leave their genes to the next generation. And that is also why males are colorful, or have displays, mating calls, bowers, and the like, for that is their way of saying “Pick me, pick me!” And it is ultimately female preference that drives the evolution of longer tails, more vigorous displays, and louder songs in males.

I can’t see how this explains the gaudy traits though. A female would always be better off with a male who does battle and wins over other males since this would be an indication of gene variants conferring strength and stamina. The bright colors and long tail feathers on the other hand impair the individual so that even if it’s somehow a proxy for health this would be largely cancelled by this impairment. The choice between a healthy male who is strong and mobile and a healthy male who is strong but attracts predators and has less mobility should be easy. Coyne mentions the American house finch as an example, how brightly colored males bring more food to their offspring, and how this might be an indication of health and it certainly gives females a direct advantage since lots of food increases the survival rate of the offspring. But this still doesn’t explain why she wouldn’t prefer a male that gets her lots of food without bringing predators in his wake. And do peacocks with large tail feathers that impair mobility bring more food too?

Coyne just fails miserably to explain this. And it’s even more disconcerting that there is so little evidence that gaudy males really produce more viable offspring – two studies to date. One of these is on frogs in which the males with the loudest call gets the females. But this is more of a physical display of strength than genuine gaudiness. This leaves us with one single study of peacocks in a semi-natural environment in Britain as the entire body of evidence. And then there is a number of studies that found no such effect; Coyne doesn’t say how many. But he does admit,

This belief, in the face of relatively sparse evidence, may partly reflect a preference of evolutionists for strict Darwinian explanations—a belief that females must somehow be able to discriminate among the genes of males.

This seems problematic, to say the least. Belief?

Debating Creationists

But even more problematic is the criticism of creationism that permeates this book. Obviously any creationist who accepts scientific method as the only way of understanding reality would have to concede that Darwin beats the Bible. But creationists are into metaphysics, they work under the assumption that there is an almighty creator – who created our ability to use scientific method in the first place. If this creator exists – and there is no way we can know – then all bets are off. Disproving God with science just isn’t science.

He also addresses the concern of evangelical author Nancy Pearcey and others who feel that the theory of evolution will undermine moral and cause social decay,

But Pearcey’s notion that these lessons of evolution will inevitably spill over into the study of ethics, history, and “family life” is unnecessarily alarmist. How can you derive meaning, purpose, or ethics from evolution? You can’t.

He also mentions congressman Tom Delay’s idea that the Columbine massacre was inspired by the theory of evolution, implying that this is nonsense. But he fails to mention the fact that one of the perpetrators, Eric Harris, entertained fantasies of superiority and of killing retarded people. At the day of the massacre he wore a t-shirt with the text “natural selection.” And Finnish school shooter Pekka-Eric Auvinen called himself a social Darwinist and who declared that, “I, as a natural selector, will eliminate all who I see unfit, disgraces of human race and failures of natural selection.”

Self-proclaimed social darwinist Pekka-Eric Auvinen.

Mass murderer and self-proclaimed social darwinist Pekka-Eric Auvinen.

Still Coyne claims that evolution doesn’t tell us to behave like these guys and that most human behavior isn’t even dictated by evolution. That may or may not be true, but that’s not the issue – it’s about how human behavior may be influenced by the theory per se, a cultural influence. Maybe some people will become inspired to acts of violence by the idea of natural selection.

And perhaps the author himself can’t handle the theory of evolution. When discussing “the sticky question of race” he admits that race is not a social construct since it is defined as differences on certain traits between populations of the same species. But he insists that the differences between races don’t amount to much since we left Africa so recently,

At the genetic level, then, human beings are a remarkably similar lot. That is just what we would expect if modern humans left Africa a mere 60,000 or 100,000 years ago.

And while he acknowledges that different groups have different intelligence and behavorial traits, he says we can’t know if this is due to evolution or not because we can’t conduct the research for ethical reasons,

Such studies require controlled experiments: removing infants of different ethnicity from their parents and bringing them up in identical (or randomized) environments. What behavioral differences remain would be genetic. Because these experiments are unethical, they haven’t been done systematically, but cross-cultural adoptions anecdotally show that cultural influences on behavior are strong.

So we have all these creative ways of dating fossil but when we come to a politically sensitive issue there is one and only one way to find evidence – and that’s forbidden for ethical reasons, so we shall never know. Personally, I think that if you can believe this nothing-to-see-move-along-folks trick then maybe belief is your forte, in which case you may prefer the Bible to this book.

Still, for some odd reason the author implies that anectdotal evidence of cross-cultural adoptions could give us a hint,

As the psychologist Steven Pinker noted, “If you adopt children from a technologically undeveloped part of the world, they will fit in to modern society just fine.” That suggests, at least, that races don’t show big innate differences in behavior.

If that’s the case then let me provide such an anecdote. A few months ago I visited a library and was using one of its computers. A White woman walks by and for some reason drops her 6-7 year old daughter next to me and walks a way to do whatever she came for. Bad parenting, right?  Normally, I would have objected to this because I know what Swedish kids are like when unsupervised. But this was a child of clearly East Asian origin. So I relax and go on working on the computer knowing – or prejudicially assuming – that I most likely will not be disturbed by her. Sure enough, she remains quiet and stationary for over an hour until her mom picks her up.

Was I prejudiced in believing in this outcome? Are East Asian adoptive children every bit as loud and rowdy as Western children? It’s almost a rhetorical question. I suspect most people share my experience that there are indeed big innate differences between Whites and East Asians. Note that this doesn’t contradict what Pinker said. That girl fitted in just fine – but her behavior was still very different from ethnically Swedish children.

Creationists Are to PC Liberals as PC Liberals Are to HBD

So it seems like Coyne and his ilk are much more similar to creationists than they care to admit. Coyne views Pearcey’s fear of evolution and its social ramifications as “alarmist” but when it comes to divergent selection for behavioural traits in humans – when his own values are at stake – he becomes defensive and says it would be unethical to find out. And that, in my view, makes him a failed scientist.

But what about Coyne’s and Pearcey’s concerns? It’s possible that spree killers are inspired by Darwin as creationists fear, and it’s equally possible that racists are inspired by research on biological differences between human races as Coyne fears. I honestly don’t know. But should we ban scientific research on sensitive issues for this reason? And if so, do we abandon research exclusively on race or do we abandon the theory of evolution altogether?  Whatever your answer is, don’t do like Coyne: pretend like you’re a scientist and the bail on it when you get cold feet.

That said, this book is pretty good introduction to some of the basics concepts of evolution, and it certainly provides insights into how politics intermingles with science in the academic community. And it’s an easy read.

The Meth Hypothesis: Why Normal People Believe in Conspiracy Theories

October 9, 2013
You wake up one day and you're Steve Buscemi. Not worth it.

You wake up one day and you’re Steve Buscemi. Not worth it.

Is America losing it? It would seem so judging by polls on weird beliefs and opinions in recent years. Here is a recent handful from Public Policy Polling (PPP),

28% of voters believe that a secretive power elite with a globalist agenda is conspiring to eventually rule the world through an authoritarian world government

37% believe that global warming is a hoax/conspiracy

4% believe shape-shifting reptilian people control our world by taking on human form and gaining power. May not sound like much but that’s almost one in 20, so it’s very likely you know a person who is perhaps wondering whether you are one of the lizards.

9% believe the government is adding fluoride to the drinking water for sinister reasons.

21% believe a UFO crashed at Roswell in 1947.

15 % believe the media or the government adds secret mind-controlling technology to television broadcast signals.

It may of course be that Americans have always been crazy but that the media is reporting more of it than before to satisfy the public’s pressing need for entertainment – it seems most news sites have a “weird” section these days.  It’s hard to find any longitudinal data on conspiracy theories, but Gallup has data on odd beliefs, often held by the same individuals, from 1990 until 2005 and it suggests an increase. But why?

The Meth Hypothesis

We already know a category of people who hold both bizarre and persecutory beliefs – schizophrenics and schizotypal personalities. We also know that amphetamines will make a normal person start thinking like these people. Psychologists will even use amphetamine addicts to study schizophrenia and schizotypy for this reason.  Could this be what is causing this increase? There may be other factors contributing to the increase in weird beliefs – the rise of the internet, increasing marijuana use, globalization and diversity, fears regarding the environment etc. But only amphetamines are proven to produce odd and persecutory beliefs (the evidence for cannabis is much weaker). So let’s look at the stats. Since there doesn’t seem to be any official statistics on the overall number of meth users, I’ve chosen treatment admissions as a percentage of the population from SAMHSA as a proxy. These are all amphetamines but they all have a similar effect and meth is the most common.


Keep in mind that this chart is of treatment admissions rather than actual use. The peak in 2005 represents people who have been doing the drug for a while before understanding that they need help. The actual use of meth must have peaked earlier, exactly when is hard to tell but given how destructive this particular drug is, it’s probably not later than sometime around 2002-2003.

Witches, Hauntings and Aliens

Now compare this chart with some others showing how many Americans believe in various weird stuff (as a percentage of the population); the data is taken from Gallup. What we’re looking for is an increase during the 1990s and a peak a few years before 2005, in this case we have data for the year 2001 as the closest fit. So, here goes,


This is not a great start, I’ll admit that. There is no gradual increase in the 1990s, but there is a small peak at 2001 and consequently a drop to 2005. This is also the belief that is the least odd with an average of 47 percent believers and 21 percent disbelievers.


This data is even less kind to my meth hypothesis. It has none of the three features and with 42 percent believers and the same percent disbelievers it’s not that odd, although clearly polarizing with few uncertain. It’s possible that since this question was specifically about the devil it could be linked to religion in a way the others aren’t.


Healing shows a gradual increase but that’s about it. Then again this is also one of the more conventional beliefs with 52 percent believers and only 29 percent disbelievers. So I wouldn’t count this one at all. A majority view is in no way odd.


Telepathy is moderately odd with 34 percent believers and 39 percent disbelievers. It has no initial increase but it peaks in 2001.


Hauntings is also moderately odd with an average of 34 percent believers and 40 percent disbelievers. This one has all the features, a gradual increase with a peak at 2001.

alien visitation

Alien visitation has 28 percent believers and 43 percent disbelievers so I’d consider it to be clearly odd. Although we only have data for three years, these do illustrate the features that support the hypothesis.


Clairvoyance, here defined as the power of the mind to know the past and predict the future, has an average of 28 percent believers and 48 percent disbelievers, again a clearly odd belief. And it shows an increase during the 1990s, and a peak at 2001.


A little surprising, astrology counts as clearly odd belief with a ratio of 25/55 believers and disbelievers. It has most of the 1990s increase but beginning with a drop, then peaks at 2001.


With 31 and 51 percent believers and disbelievers this is also a clearly odd belief. And it has all the right features.


At 23/51 believers and non-believers, reincarnation is also clearly odd. It has the year 1994 that ruins the initial increase but it shows an increase from 1990 to 2001 so overall there is an increase, followed by a local peak at 2001. 4 out 5 years confirm the hypothesis.

communicating with the dead

Also a clearly odd belief (23/54), with same flaw that the previous chart had – all years except 1994 confirms the hypothesis. The peak in 2001 is of the same magnitude as that of 1994.


This is my personal favourite. It’s what I’d call a very odd  belief with only 19 percent believers and 69 percent disbelievers. Witches are also malicious agents that plot against people, making this belief very similar in nature to conspiracy theories. The chart has all the right features.


Finally, channelling, the ability that some have to go into a trance and let spirits talk through them. This is also a very odd belief (9/66) that fits the meth data perfectly.

Summing Up the Evidence

Which of these beliefs should be considered sufficiently odd? We can certainly not say that spiritual healing is an odd belief since it is held by a small majority. As for the rest, it’s admittedly a bit arbitrary but, I would define a belief as odd if it has fewer believers than disbelievers, which seem like a minimum requirement. This means that healing, possession and ESP are out, leaving us with 10 odd beliefs. So how well did these 10 confirm the meth hypothesis?

7 out 10 showed an absolute peak at 2001. Of the rest telepathy and communicating with the dead showed shared a maximum peak at 2001 with another year. The remaining belief in reincarnation showed local peak at 2001. That’s pretty peaky.

As for a continuous increase in the 1990s there are three categories: 5 had unequivocal increase throughout the 1990s, 4 had overall increase from earliest year to 2001 but interrupted with a local decrease (for hauntings this decrease was very small), and one, telepathy, had the same value for 1990 and 2001. No overall decrease at all.

So the data seem to support the hypothesis pretty well. But there are of course other possible factors to consider,

Alternative Explanations

As I said earlier, marijuana is sometimes mentioned as a drug that could contribute to schizotypal and outright schizophrenic thoughts and beliefs. But unlike meth, this drug has increased continuously since the early 1990s and has still to peak. Another candidate is the internet. I’m not going to do a chart for it but the number of internet users is constantly growing so no peak there either. Yet another candidate could be changing demographics. Perhaps the Catholic immigrants to America bring their superstitions with them? But looking at Mexicans, the overwhelmingly largest Hispanic group, there is no peak, not even a local, in their part of the population, only a continuous increase over the years.­

How Can This Be?

But how does this happen? How does such a small group – according to most estimates just a few hundred thousand –  of people have such influence?  One reason is that a person holding an irrational belief is usually more interested in it than say a regular Christian is about transubstantiation. They will obsess about it constantly. Like former meth user Fergy Duhamel of the Black Eyed Peas says in an interview,

I had about 20 different conspiracy theories. I painted the windows in my apartment black so they couldn’t see in.

When a schizophrenic on the sidewalk rants about the government this doesn’t persuade anyone, but a more coherent and presentable schizotypal person can be appear much more convincing. And my guess is that a meth user online can probably do a pretty good job at selling his theories too – especially when other meth users are online on various forums saying similar things. While what they are saying may not make much sense it doesn’t have to. Just saying it repeatedly and with great conviction goes a long way. One thing social psychology (it’s not all bad) teaches us is that repetition is an effective way of persuasion, especially if you vary the way you say it a little – which is exactly what you get from an army of delusional meth addicts sitting up all night preaching their peculiar gospel.

But can they really sit still while on meth? It seems so. Because not all meth addicts are out partying or committing crimes. Some stay indoors cooked up in their houses or apartments. In an article in The Kernel, science writer Greg Stevens shares his experiences of some middle class meth addicts. One of them is “J”,

The window shades are drawn tight because J usually stays awake for 70 to 100 hours at a time. He knows that if the neighbours can see light coming from his house at all hours of the night, they will begin to suspect something. J has also placed a folding room divider covered with tinfoil in the hallway just inside the front door. This is to block any kind of infra-red or other types of electromagnetic spying equipment that the neighbours might be using.

It’s not hard to imagine how an intelligent, educated and hermit-like person like J combined with 20 conspiracy theories like Fergie would make an ideal person for spreading these ideas over the internet. If we guesstimate that there are 300K meth users in America and ten percent of them rant about conspiracies online, then that would be roughly twice as many as there are lobbyists in Washington. And they are no doubt much more persistent.

Human Biodiversity – Things You Are Not Supposed to Know About

June 5, 2013

As someone interested in personality, I find the field known as Human Biodiversity (HBD) to be fascinating. For those who are unfamiliar with it, HBD is a field in which controversial issues regarding human nature are explored, debated, and above all, brought out into the open. HBD is about things ordinary scientists and journalist would prefer you didn’t know about. Plausible but suppressed facts and theories on things like how inbreeding has turned people in the Muslim world more “tribal” than others, resulting in corruption and violence and low national IQs. Or how homosexuality actually has a very low heritability and may be caused by a pathogen. Or how low intelligence may be a greater health problem than overweight, how ethnic groups may differ in behavior for genetic reasons and how this affects society. And so on.

Often discounted as amateurs, racists, sexists etc, HBDers are a mixed bunch of people who pursue these issues with little or no funds at their disposal. They are rarely prominent experts in their fields – because that would no doubt get them fired – but they have plenty of education and intelligence, and I think any honest person who listens to what they have to say will have to agree that they offer more than just shock value. Human nature includes our dark and problematic sides too. A true scientist delves into that as well, because he holds the truth above all other considerations. In that sense HBD is more science than a lot of what passes as science in Academia.

There is no official introduction to HBD as yet, but as a next best thing you can read Jayman’s 100th post  published today, which offers a well-written overview of the field.

Book Review: Quiet – The Power of Introverts in a World That Can’t Stop Talking (2012) by Susan Cain

April 25, 2013
The author Susan Cain doing her TED talk.

The author Susan Cain doing her TED talk.

A book just about introversion? At first blush, this may seem like a too narrow focus, but according to Cain, this trait is the “single most important aspect of personality.” She makes a good case by listing the various things in life that are linked to the dichotomy of Introversion/Extraversion – choice of friends, career and education, exercise, adultery, risk-taking, delayed gratification, to mention a few.

Why America Became Extraverted

But in spite the many qualities inherent in the introverted mind, American society is still biased in favor of Extraversion, Cain argues. Already in school, the outgoing jocks and cheerleaders are popular while introverts go under labels like nerds or weirdoes, outcasts that most kids avoid. The same attitude can be found among adults, although usually expressed less bluntly. Studies show that talkative people rate as smarter, better-looking, and more interesting than the rest. This bias has even been prominent in psychology and psychiatry where introversion often has been viewed as dysfunctional or outright pathological. Adler is perhaps the best example of the academic bias (in his terminology introverts are called the Avoiding type and extraverts the Socially Useful type).

But things weren’t always like this. Cain points to what historian Warren Susman has called the transition from the Culture of Character to the Culture of Personality that took place in America in the early 1900s. This change was supposedly brought on by the industrialization and urbanization. The mass market and city life meant that you had to be able to get along with strangers in a way you never had to when living in a village or a small town. To illustrate the change, Cain presents Susman’s findings on word frequencies in self-help books and advice manuals of earlier times. In the 1800s the words that were most frequent were, Citizenship, Duty, Work, Honor, Integrity and similar. In the early 1900s these words were gradually replaced with others like Magnetic, Fascinating, Stunning, Attractive, Glowing, Dominant, Forceful and so on.

While this shift is interesting, I remain skeptical to the idea that external forces brought on such a dramatic shift in national personality. Given the how heritable personality traits are, and especially how little shared environment means, it seems more likely that this shift was due to an influx of extraverts. The early settlers were Puritans and others who came to practice their religion in peace, and they came from Northwest Europe. This no doubt was a more introverted group than the European average. When large scale immigration resumed around 1830 it wasn’t so much people fleeing religious persecution; it was people who had heard stories about the land of opportunity, and a lot of them came from Southern Europe. This demographic change seems to provide a better explanation to the emerging Culture of Personality, which perhaps more appropriately should be called the Culture of Perception.

The American Business Culture

When you compare America with Europe or the rest of the world, it’s tempting to view extraversion as an important factor in how America became so successful. Cain, however, rejects this idea. She visits Harvard Business School which is obsessed with social activities and perception – “good luck finding an introvert here” one student told her. But in real life, you’ll find loads of successful introverted CEOs, like Bill Gates, Brenda Barnes and many others. Studies linking leadership to extraversion are based on modest correlations and, more damaging, leadership is rated on impression rather than results. The personality of a good leader, Cain says, depends more on the situation. According to result-based studies, introverted leaders are good at handling active employees, putting their ideas to use, while extraverted leaders are better at inspiring passive employees, rallying the troops.

But in the business culture these insights are not taken to heart, most likely because the business world is full of extraverted salespeople who have been told and want to believe that their social skills will bring them to the top. This culture, according to the author, is irrational and destructive in that it is based on faith rather than facts. A typical example is the open office plan, which research show is linked to low productivity, high blood pressure and conflicts in the workplace – but it’s still popular because it promotes the extraverted ideal.

Cain even claims that the current Great Recession we are in right now is largely due to those pesky extraverts. That people who try to warn about potential dangers are seen as weak and ungrateful. She quotes from Kurt Eichenwald’s book Conspiracy of Fools about how when in 2001, Vincent Kaminski, a managing director of Enron, just before the bankruptcy, tried to warn about the problems his company was in and what kind of feedback he received,

There have been some complaints, Vince, that you’re not helping people to do transactions,” the president of Enron told him, according to Conspiracy of Fools, a book about the Enron scandal. “Instead, you’re spending all your time acting like cops. We don’t need cops, Vince.”

And a more general quote directly from Kaminski,

“Many times I have been sitting across the table from an energy trader and I would say, ‘Your portfolio will implode if this specific situation happens.’ And the trader would start yelling at me and telling me I’m an idiot, that such a situation would never happen. The problem is that, on one side, you have a rainmaker who is making lots of money for the company and is treated like a superstar, and on the other side you have an introverted nerd. So who do you think wins?”

I think this part of the book is very interesting, and alarming since we know that this culture is alive and well, eagerly waiting for new opportunities with little concern for the risks involved. You have to wonder if maybe places like Harvard Business School should have a quota for introverts. Not to say that introverts are better at this game – America is a great example of entrepreneurship – but it’s not the 1950s anymore, today’s world is complicated and more caution, reflection and analysis is needed.

The Introverted Ideal

It’s understandable that an introvert living in America feels unappreciated and may want to compensate for this in some ways. But reading this book it’s hard not to feel that Cain is replacing the extraverted bias with an introverted one instead. She constantly talks about the virtues of Introversion. How it’s linked to intellectual and artistic achievements, empathy, integrity, conscientiousness, persistence and so forth. Extraverts, on the other hand are generally described as simple folk who are full of energy but without any judgment or sophistication. No, she doesn’t say that but that’s what it sounds like. The title of the book alone gives you a hint of this: extraverts are the ones who can’t stop talking.

Yes, there is a bias against introverts, and yes we should do something about that. But using that as a cover for unbridled self-glorification is not an improvement.

The Biology of Introversion

More interesting is Cain’s foray into the biological and evolutionary roots of Introversion. Like me, she prescribes to the optimal arousal theory which states that variation on this trait is a matter of sensitivity. An introvert is more easily aroused and will for that reason interact with their environment in a way that keeps stimuli at a low level – staying indoors, having just a few friends they know well etc. But what kind of stimuli are we talking about? Psychologist Hans Eysenck was the first to answer this. He claimed that it was a difference in the Ascending Reticular Activating System (ARAS) that made some into introverts and other extraverts. Others, like Jerome Kagan has found a correlation between the Fight-or-Flight response and this trait, although since this is an emotional response others have pointed out that this is more related to Neuroticism. Personally, I think a sensitive ARAS could trigger the fight-or-flight response more easily making this response and indirect measure of introversion/extraversion. Then there is the theory of Reward Sensitivity, the idea that extraverts are more rewarded by stimuli. This theory would essentially make Extraversion the same thing as Sensation Seeking – a trait of thrill-seeking and hedonism.

The author presents a lot of interesting research on this although it feels like they are all finding things that relate to this trait without being able to pinpoint it. Introversion is not fearfulness or aggressiveness as measured by the Figh-or-Flight response, and extraversion is not hedonism either – there are plenty of fearful extraverts and hedonistic introverts. The nature of this trait must be something else. I think Eysenck was right on the money with his ARAS theory – at heart it is a simple matter of attention and wakefulness, although all these system appear to interact in complicated ways.


As for the evolutionary reason for the Extraversion/Introversion trait, Cain mentions one theory by psychologist Kenneth Olson, who claims that Extraversion is the mark of the migrant, the more fearless person. This, Cain (and presumably Olson) mean, would explain why White people are more extraverted than Blacks or Asians. I can buy that Whites score higher on Extraversion than Asians, but are Africans and their descendants in America and elsewhere really that quiet and reclusive? Are African-American kids bullied in the school yard for being nerdy or socially inept and less cool than the other kids? Perhaps the Big Five, a problematic measure for sure, is to blame, or maybe it’s the incompatibility of cultures, but something is off here.

Still, the difference between America and Europe could well be that those who migrated were more extraverted, more sensation seeking and less fearful than those that stayed behind. But generally speaking I think the theory that evolution favored extraverts in a warmer climate and introverts in a cooler climate makes more sense. Cain practically admits that something like this could be a possibility when she mentions Kagan’s impression that high-reactive children (statistically related to Introversion) tend to have blue eyes more often than low-reactive children. Sadly there is hardly any research on this at all, so there is no way to know for sure. But kudos to Cain (and Kagan) for even talking about such “dangerous” notions.

Cain goes on to present various evolutionary theories. Like the simple but sensible idea that introverts add a bit of caution necessary for the group to survive. A purely extroverted group would crash like Wall Street – but with no one to bail them out.  Or Jung’s idea that Extraversion represents a strategy of high fertility and high mortality and vice versa. This would be in line with the climatic theory but it also fits with the idea that extraverts are pastoralists who are fighting to protect their cattle and most likely stealing other people’s cattle. Introverts would instead be the agriculturalists who will expose themselves to less risk and have fewer children and think more ahead. Cain mentions an interesting study about a gene variant linked to the trait Novelty Seeking, which correlates to both Extraversion and Sensation Seeking. Among Kenyan pastoralists with this variant were found to be better nourished than Kenyan farmers with the same variant. This may lend evidence to the idea that Extraversion is an adaption to a riskier and more improvised way of living. (This is also relevant to my previous post about the trait of Tribalism.)

A Yay or a Nay?

I have mixed feelings about this book. Cain’s idea of introverts as an oppressed minority, although partly true, feels a bit silly. As an introvert I object to her idea that we are “like women in man’s world.” Women are still oppressed and victimized in numerous ways whereas introverts can become both rich and powerful in any culture without anyone objecting to it.

That aside, she does write well, and although theoretically confusing, this book offers a lot of interesting facts, and she even dares to touch on some sensitive issues. So all things considered, it’s a yay.

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