Men Vary More Than Women in Personality

March 11, 2013
I was going to illustrate this post with a variety of men, but everyone was so ugly I chose actress Juliet Landau instead.

I was going to illustrate this post with a variety of men, but everyone was so ugly I chose actress Juliet Landau instead.

It’s well known that men and women differ on some personality traits, most notably neuroticism, when averages are compared. But another way to compare the sexes is by looking at how much men and women vary within their groups. In a new study, psychologists Peter Borkenau, Robert McCrae and Antonio Terracciano have done just that. Using data from 51 cultures with more than 12K participants they have looked at observer ratings of someone each participant knew well. Using a measure of the Big Five, they found that men were generally rated with more variation than women on all traits except neuroticism, which was slightly more varied for women. They also found that women rate people with more variance than men.

Why Would Men Be More Varied?

One possible explanation for this could be evolutionary. While women have a high parental investment, their reproductive success has depended on physical health and social skills. Men have had more ways to be reproductively successful – the can be hunters or gatherers, leaders, highly organized, manipulative etc. Since all of these strategies relate to personality this would mean that more variation in traits would be selected for among men than women.

A case could also be made for gender roles influencing variance – men are simply allowed a broader range of behaviors than women. This is one of those nature/nurture questions – do social norms form behavior or does behavior form the norms? One way to settle this question (in this instance) would be to look at variation in behavior that violates social norms. This can be easily found in personality disorders, conditions that constitute extreme and maladaptive personalities. These are much more common among men than women, and a big reason why the prison population is made up to 90-95 percent by men. Their behavior is extreme and unacceptable, contradicting the idea that social norms can explain the variance. So more likely, this is a product of evolution. This of course all depends on if you view personality disorders as extreme variants of normal personality or not, but both behavioral and genetic links between the two suggest that they are.

Why Do Women Give More Varied Ratings?

This may relate to the fact that women varied more on neuroticism, a trait relating to social interactions. It may be that their social skills – observation of others no doubt being a crucial part of these skills – make them more accurate judgers of personality. The authors refer to other research that has reached this conclusion. Which makes me wonder: if women are better judges of character, why aren’t they the preferred choice of raters in personality research? It’s also interesting to note how few women there are in this field given that they are superior to men in this very fundamental aspect.

Is Male Variation a Good Thing?

Given what I just said about the prison population, it’s far from certain that this male variation in personality is a good thing, neither for the individual nor for society.  After all, evolution is not adaptive in the short term; there are plenty of examples of how our evolutionary nature collides with the modern environment, obesity being the most obvious. That said, crime is far from the only aspect of this variation. According to the study it concerns four of five basic factors of personality. Luckily the study included some social variables. Here is what they found,

The sex differences in variability in personality were more pronounced in the more developed, more gender-egalitarian, and more individualistic societies.

This suggests that male variation is a good thing. One explanation could be that nations compete with ideas. And variety in personality means a variety in how people in a country think, which makes for a variety of ideas that in turn translates to wealth. This variation largely coincides with IQ measure of different countries so it’s a little hard tell exactly how much of the wealth is due to intelligence and how much is due to variety.

Why Do Countries Vary in Variety?

This is probably something those Human Biodiversity buffs might have an answer to. It seems likely that inbreeding would reduce variance as well as intelligence. In line with this idea, Muslim countries (known for very high levels of inbreeding and low IQs) had on the average a lower level of male variance  and those who were above average were very close to it. Some countries break this pattern by showing little male variance but high IQ levels, most notably Hong Kong and Japan. But overall, variety seems to be of great importance. This is a field of research that is still pretty new so it will be interesting to see where it leads. No doubt some traits will be more important than others, and some of these may not be captured in the Big Five model. Honesty/humility and sensation seeking come to mind. And different combinations of traits might also be important. I’ll get back to this if I find something interesting in the numbers.

 


Solving a Mystery for Satoshi Kanazawa

February 14, 2013

Over at the Big Think, psychologist Satoshi Kanazawa lists what he considers the unsolved mysteries of evolutionary psychology. One of these mysteries is the question of why people with many siblings have many children. According to Kanazawa this doesn’t make any evolutionary sense at all,

This is because people with many siblings have the option of investing in their younger siblings and increasing their reproductive success by doing so.  Humans are just as genetically related to their full siblings as they are to their own biological children; both share half their genes.

I think the solution to this mystery can be found in viewing extraversion and introversion as evolutionary strategies. There is plenty of research showing that extraverts are more sexually active than introverts. This would lead to them having more children (we’re dealing with an evolutionary time scale so we can ignore the effect of contraception), and since it’s also a highly inheritable trait it would make a person with many siblings more likely to have extraverted parents and for that reason he is likely to have inherited their extraversion and have many children himself.

But if so, why aren’t we all extraverts – if it’s enables us to spread our genes so well? To understand this I think we need to look at differences in this trait between people living in environments with varying degrees of resources. In good times with plenty of food available, extraverts would propagate and spread their genes by having many children but a relatively small parental investment. But sooner or later hard times would come and then the introverted strategy of few children and high parental investment would pay off. If there is a scarcity of food, giving all you can spare to one child rather than sharing it between 4-5 children becomes a winning strategy. That way, hard times would ensure that genes for introversion would survive.

Now, it’s a fact that different regions vary in resources. People who have originated in a cold climate, or at least in a region with long cold winters should, if this theory is correct, have a higher level of introversion than people from warmer regions. We are all familiar with the stereotypes of the introverted northerners and extraverted southerners. Is there any truth in it?

Looking at extraversion scores from Richard Lynn’s study (1995) of 36 (I omitted Iceland because it has a microscopic population) nations there is actually a bit of a pattern supporting the theory.

The average level of extraversion for all countries was 18.4. But those who originated in a cold climate (Nordic or Central Asian) averaged at 17.2, while those originating in a warm climate averaged at 20.0, with intermediary countries averaging at 17.9.

Extraversion scores by country and climatic origin.

Extraversion scores by country and climatic origin.

I’m probably not the first person to have this idea but since Kanazawa insists that it’s a mystery and this seems to be a plausible explanation, I thought I should share it.


Is Testosterone and Social Mobility Causing Anorexia in Women?

August 27, 2012

You can never be too skinny or too rich. Nancy and Henry Kissinger.

A recent study published in Personality and Individual Differences 51 (2011) showed a link between prenatal testosterone levels (as measured with the ratio between the second and fourth finger) and anorexia.  Why would that be?

Earlier, several studies have found that men as well as women with high levels of testosterone react with stress specifically when their social status is in jeopardy and they become very eager to regain their status.

But social status is not the same for men and women. Traditionally, but also in present time, men measure status in terms of social dominance and power. Women, on the other hand are more likely to assert themselves by weight control. Because from an evolutionary standpoint women haven’t had much power other than that of attracting the powerful male. And one way to do that is to look good and stay in shape.

The question is how normal weight control can turn into anorexia. I think this relates to how modern society clashes with our evolutionary nature. As a species, we have lived most of our time in small groups that have been relatively equal. People have always fought to climb the social ladder and to maintain their positions. But modern society has enormous class differences. So anyone high testosterone person in the upper part of the hierarchy can now fall so much further down, even lose their place in it altogether.

This explains why white women are more anorectic than women of other races, and why women from the upper class or upper middle class are more affected than lower classes. They are the ones who are highest in the hierarchy so they are most likely to end up in a situation in which they feel their status is being threatened. And in today’s society, social mobility makes this threat more realistic than ever. This increased threat from the modern environment probably makes some of these high testosterone women go overboard in their attempt to maintain their status. They lose perspective on things and their genetic programing gets the better of them.

This is just a theory of course proposed by the late Linda Mealy and others. But it makes sense in light of this study. And it makes a whole lot more sense than conventional wisdom of how it’s the media or the fashion industry or evil men who pressure women to lose weight. Any part of those industries with an agenda to change women rather than to make money would be outcompeted. And men are horny, regardless of where in the social hierarchy they are. They would not pressure women into becoming something they found sexually repulsive.

So that’s why Henry Kissinger, who once proclaimed that power makes a man sexy,  judging by the picture above, thought skinny does the same for a woman.


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