Having said that, men are cheats. A developing zygote needs a certain amount of nutrients from the two sex cells (gametes) that have combined to form it. Yet sperm are tiny, and the majority of nutrition is provided by the female egg cell. Hence, the male gamete is like a date who refuses to go halves on the bill, but instead searches for a partner who will provide them with the most extravagant gifts; whilst the female gamete is the sugar daddy of the sex cell world.
Therefore, sperm have evolved to be fast and numerous so as to reach a female egg cell before any other male gametes, whilst female gametes have evolved to be nutrient-rich. From these first principles, how far can we explain the presence of sex roles in society? It is clear that females invest more heavily per gamete than males, and therefore there is a difference between the two sexes in terms of the way in which they should maximise their reproductive output; a man should attempt to impregnate everyone, whilst a woman should use up her eggs on males who are expected to produce fit offspring. Thus, men should compete for females. It is relatively easy to think of examples of this in society; for instance, that guys approach women more often in clubs than vice versa. Then again, Dawkins argues in The Selfish Gene that since women tend to take longer on their appearance this is evidence for males having become the sex that is competed over. Clearly this makes a number of assumptions, but nevertheless the two examples above go to show how difficult it is to extend evolutionary theory to explain human behaviour.
Evolutionary biologists and feminists have often clashed horns. For instance, in the 1970s, sociobiologists used evolutionary theory to argue against the burgeoning women’s liberation movement. Even nice, beardy Darwin reasoned that since females of most species resemble the young of the species, males must be more ‘evolutionarily advanced’. Darwin believed that females were more competed for by males than vice versa (since one male can have many children, whereas a female is limited to having a few children), and so males of different species evolve under sexual selection to be more intelligent. More recently, take the Cambridge don Martin Sewell, who, in a written response to a female academic’s lament about the glass ceiling in her chosen scientific discipline of anatomy, chose to remind her of his recent article, which apparently ” seeks to explain why men are better equipped than women to do science and engineering, and why there are more men than women in higher offices.” As a biologist I feel obliged to point out that Martin Sewell is actually an economist (not an evolutionary biologist), but nonetheless it seems that his comments do represent a lingering suspicion in society that perhaps women’s position in society is a result of inherent differences in the genetics between the two sexes, rather than a result of the environment. Essentially this is a nature vs. nurture argument; do women fail to reach positions of power due to some genetic difference, or is it purely a result of societal pressures?
The most obvious attribute to run a company is probably intelligence; could this have evolved differently in men and women? In short, no; IQ tests tend to give the same result (with a point or two of difference) between men and women. It used to be the case that the male IQ was consistently higher than the female IQ, (as would be expected with limited education available to women) but in 2012 women’s IQ overtook men’s. The female IQ has been consistently increasing at a rate faster than men’s, and so it seems likely that as females have now caught up their rate of IQ increase will decrease (unless women turn out to be more intelligent than men.)
However, do the sexes differ in specific types of intelligence? For instance, it has long been argued that boys are more likely to have mathematical talent than girls while girls are more likely than boys to have verbal talent, leading boys to do better in mathematics than girls. The last meta-analysis of mathematical ability was published last year; after finding that ‘girls in general get better grades than boys in mathematics courses’ the authors concluded that there was ‘little support for the assumption that boys, on average, demonstrate higher mathematical abilities than girls’. However, the authors did argue that societal stereotypes tended to put women off applying for courses in the physical life sciences and engineering. Likewise, it seems likely that the lack of men in English courses is due to societal pressures rather than an inbuilt lack of verbal skill. This makes sense; from an evolutionary perspective it is very difficult to construct an argument for why women would be better at verbal skills and why men would be better at maths, and indeed a scan of the literature shows that this seems to be the general conclusion.
Do the sexes differ much at all? ‘The Gender Similarities Hypothesis’ is a psychology paper from 2005 that consists of one of the most thorough meta-analysis of various different psychological and motor abilities between the two sexes, from self-esteem levels to throwing ability via neuroticism. The study concluded that there was little difference between the two sexes in pretty much anything, apart from some motor abilities (such as throwing) and aggression. Aggression showed a moderate gender difference. Likewise, a very recent study tested for differences between each gender in parameters including masculinity, femininity and inclination to science. They concluded ‘that [the different parameters] unambiguously represent exemplars of the same underlying attributes rather than qualitatively distinct categories of human characteristics.’ The conclusions of both of these studies are backed up by a meta-meta-analysis of 46 meta-analyses. It’s important to think about how incorrect stereotypes adversely affect men as well; one of the paper’s conclusions was that men had as low self-esteem at the start of adolescence as females, yet were less likely to get professional counselling.
There is little or no evidence for personality differences between the genders, with the exception of aggression. Perhaps it is aggression that has caused the difference in pay/power between the two genders in the first place. It would make sense that the first people to get into power happened to also be the most aggressive ones (e.g. the ones that literally fought the others off) and that they would in turn favour people with similar traits to themselves (such as being male and/or aggressive) to also be put into similar positions. Thus an overrepresentation of men would be put into such positions, and then it seems fairly intuitive that stereotypes could pop up that assumed that females were not in positions of power due to deficiencies in certain useful traits. Once stereotypes are prevalent it is difficult to break free of them. For instance, it is worth mentioning the existence of the stereotype effect; in a seminal paper in 1995 by Steele and Aronson, it was shown that African-Americans tended to perform worse than their white counterparts in testing situations when negative stereotypes about African-Americans were relevant. This was not the case when relevant stereotypes were not present. This same effect has been demonstrated many times in women; for instance, on their performance in maths tests. Given the on-going prevalence of gender-specific stereotypes about intellectual ability, if anything it’s impressive that women are now doing as well as they are now doing in courses such as maths.
So with the support of the considerable amount of data available to us, we can say that women and men have far greater in-gender personality and intellectual differences than between-gender differences (again with the exception of aggression.) However, can we explain differences in sexual behaviour from evolutionary principles? This is more plausible from an evolutionary perspective than explaining personality differences. Personality differences could only potentially have evolved once pre-determined roles that favoured different personality traits (in terms of reproductive success) had existed for a few million years; this involves lot of dodgy caveats and isn’t particularly plausible. However, differences in sexual behaviour could be favoured by selection straight away, owing to the different investment in gametes between the two sexes. Then again, even differences in sexual behaviour seem to be smaller than expected. The most recent 2012 study into gender differences reported that ‘sociosexuality showed no evidence of a gender taxon, but did show some signs of a small taxon of men high in SOI’ – SOI is a measure of willingness to have sex outside of a committed relationship.
The genetics that determine personality (and even sexual behaviour) between the genders don’t seem to differ that much. But even if it did, how much would it matter? There is a tendency to think that genetic predispositions towards certain behaviours or skills are irreversible. For instance, imagine taking a genetic test which determines that you have genes associated with poor mathematical ability. This would somehow be more gutting than being told you are poor at maths as a result of daydreaming in all your maths classes. Yet in many cases the two examples are equivalent in terms of the amount you would need to work to catch up with everyone else. Obviously this isn’t true in all cases (for instance if you are dyslexic, no amount of work will make you not dyslexic), but nevertheless the example demonstrates our tendency to forget that most genes are not all-or-nothing; there are huge numbers of genes which each contribute a little bit to a certain cognitive skill. The brain is also plastic; that is, its very structure will change as a result of the environment. If you work hard at maths, the connections in your brain that help you work out a mathematical problem will become stronger. If you have really bad genes for doing maths this might not be significant, but in the majority of cases working extra hard will bring you up to the level of your peers.
We are also not slaves to maximising our reproductive fitness; if we were, how could we have invented the contraceptive pill? Evolutionary arguments are often used as if they are an all-powerful force, when in reality our ability to think allows us the ability to act in ways that are counter-productive to the very function that natural selection designed us for. In conclusion, there are no significant genetic differences between the genders in terms of intellectual ability or personality traits, and so there is no excuse for why we haven’t sorted out the predominance of men in certain roles within society.