Econstudentlog

The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature

Here’s a link.

I’ve read roughly half the book. It’s interesting, but quite speculative. As with all popular science books it sort of assumes the reader doesn’t know very much about anything, and this of course means that there’s quite a bit of known stuff covered here along the way. The notes/references do quite a bit of the work. So far I’ve enjoyed reading the book, but I’m not that impressed; I’m probably currently at a three-star evaluation, but a little closer to four than two. Compared to a textbook it’s very easy to read.

Some quotes from the first half of the book:

“most experimental psychology views the human mind exclusively as a computer that learns to solve problems, not as an entertainment system that evolved to attract sexual partners.”

“Natural selection [refer] to competition within or between species that affect relative survival ability. Sexual selection [refer] to sexual competition within a species that affects relative rates of reproduction. […] Under natural selection, species adopt to their environments. […] Under sexual selection, species adapt too, but they adapt to themselves. Females adapt to males, males adapt to females. Sexual preferences adapt to the sexual ornaments available, and sexual ornaments adapt to sexual preferences.
This can make things quite confusing. In sexual selection, genes do not code just for the adaptions used in courtship, such as sexual ornaments. They also code for the adaptions used in mate choice, the sexual preferences themselves.”

“brain size within each sex is correlated about 40 percent with general intelligence” (I did not know that!)

“Short-term mating is exciting and sexy, but it is not necessarily where sexual selection has the greatest effect. Human females, much more than other great apes, conceal when they are ovulating. This means that a single act of short-term copulation rarely results in pregnancy. Almost all human pregnancies arise in sexual relationships that have lasted at least several months, if not years. Modern contraception has merely reinforced this effect. […] when it comes to choosing sexual partners for long-term relationships, men and women increase their choosiness to almost identical levels. They also converge in the features they prefer.”

“By suggesting that sexual selection plays a major but neglected role in evolutionary innovation in general and the human mind’s evolution in particular, I am proposing a sort of marketing revolution in biology. Survival is like production, and courtship is like marketing. Organisms are like products, and the sexual preferences of the opposite sex are like consumer preferences. Courtship displays are not a mysterious luxury soaking up excess energy after the business of survival is accomplished. Rather, they are the only way to get one’s genes into the next generation, by fullfilling the sexual preferences of the opposite sex. Survival only matters insofar as it contributes to courtship. If nobody wants to mate with an animal, there’s no evolutionary point in the animal surviving.”

“Our ancestors did not spend all their time worrying about survival problems. They were among the longest-lived species on the planet, which implies that their daily risk of death was miniscule. Like most great apes, they probably spent their time worrying about social and sexual problems.”

“In most primate species, the distribution of food in the environment determines the distribution of females, and the distribution of females determines the distribution of males. When food is so dispersed that females do best by foraging on their own, males disperse to pair up with the lone females. This gives rise to monogamous couples. It is a fairly rare pattern among primates […] When food comes in patches large enough for several females to share, they tend to band together in small groups to find the food, and to protect each other against predators, unwanted males, and competing female groups. As long as the female band is not too large, a single male can exclude other males from sexual access to the band […] This ‘harem’ system of single-male polygyny is fairly common in primates. […] When food comes in still larger patches, female groups can grow too large for any single male to defend them. the males must then form coalitions, resulting in a complex multi-male, multi-female group […] Our hominid ancestors probably lived in such groups, in which sexual selection gets more complicated. […] Most children were probably born to couples who stayed together only a few years. Exclusive lifelong monogamy was practically unknown. The more standard pattern would have been ‘serial monogamy’: a sequence of nearly exclusive sexual partnerships that were socially recognized and jealously defended.” (This last part I consider to be highly speculative, and the notes/references are basically doing all the work here. Given the paucity of the available archaeological evidence – which I’m familar with – and the uncertainties involved when drawing conclusions and inferences based on the behaviours of other great apes, I think there’s a fair amount of uncertainty related to to which extent this account is true. There’s a lot we don’t know and can’t ever know about what was going on back then.)

“David Buss has amassed a lot of evidence that human females across many cultures tend to prefer males who have high social status, good income, ambition, intelligence, and energy – contrary to the views of some cultural anthropologists, who assume that people vary capriciously in their sexual preferences across different cultures. […] [It is a] universal, cross-cultural pattern that men care more about a partner’s age than women do, men generally preferring partners younger than themselves, and women generally preferring partners older than themselves. […] There is strong evidence from evolutionary psychology that men in modern societies generally prefer the physical appearance of women around 20 years old to those who are older (or younger). […] there has been much less research on the age at which women’s minds are most attractive.”

“our ancestors were highly social primates living in groups with children, relatives, and friends. Sexual relationships began and ended within family and tribal contexts.
If mate choice favours good genes, it can be useful to meet a potential mate’s blood relatives, because they share some of the same genes. An individual’s kin give additional information about their heritable fitness. If an intelligent man has foolish brothers or a beautiful woman has ugly sisters, this may lower their attractiveness as potential partners […] Given two sexual prospects who appear to display equal fitness, the one whose relatives appear healthier, brighter, more attractive, more fertile, and more successful probably has higher actual fitness. Since our ancestors tended to live in kin groups, there were plentiful opportunities for mate choice to take into account this sort of kin equality.”

August 21, 2013 - Posted by | anthropology, books, evolution

3 Comments »

  1. “David Buss has amassed a lot of evidence that human females across many cultures tend to prefer males who have high social status, good income, ambition, intelligence, and energy…” – Is Mr. Buss perchance a tenured professor at the University of the Blindingly Obvious?

    “If nobody wants to mate with an animal, there’s no evolutionary point in the animal surviving.” – This is an interesting one. It is obviously true on the face of it, but… Survival is a necessary, although not sufficient, condition for procreation. James Dean did not have much “evolutionary success”, for lack of a better term. I hope, for the sake of the field of evolutionary biology, that Miller’s insight is not groundbreaking. Only an idiot would interpret “survival of the fittest” as “live to an old age without progeny” – it’s a statistical concept, per Dawkins. What survives is genes, not individual organisms. On a different, speculative note, since we are talking statistics and probabilities… Drawing on the previous, “blindingly obvious” quote: I’d expect that in humans (not necessarily, or likely, in other species) survival, or long life, would have a high correlation with status, wealth, and wisdom/experience (proxy for intelligence?). I have this nagging suspicion that “evolutionary” fields have a lot in common with macroeconomics – they describe well a world where you can assume (or you observe) many agents that display little variance in their characteristics and behavior/preferences. Extrapolating those insights to human systems does not work well – I would guess that, barring physical differences between males and females (Anglerfish!), Homo Sapiens has the highest intra-species variability on most criteria, including many that flat-out do not apply to other species (e.g. religion). Trying to model human interactions based on averages seems to me to be the “epic fail” of modern social sciences.

    Cheers!

    Comment by Plamus | August 27, 2013 | Reply

    • “I hope, for the sake of the field of evolutionary biology, that Miller’s insight is not groundbreaking.” That insight isn’t – I think it’s been taken for granted for decades (my parents are both educated in the field of agricultural science/agronomy and since before the age of ten I’ve sort of taken procreation rather than survival to be the key variable in that equation – when you have parents with that background, you learn about Darwin a long time (sometimes a very long time) before you master basic algebra..).That sexual selection may explain our large brains – the main message of the book – was, I believe, a slightly different matter in that at least some of the arguments supporting the idea are new, although I don’t know if they’re actually ‘groundbreaking’.

      “I’d expect that in humans (not necessarily, or likely, in other species) survival, or long life, would have a high correlation with status, wealth, and wisdom/experience (proxy for intelligence?).” First, in the period during which most of the selection making us who we are today took place, the concept of wealth did not exist. Wealth is a New Concept (Miller actually makes this observation himself in the book). Second, status confers major survival- and reproductive advantages in many species besides humans. Third, one of the main messages of the book is that bigger brains were selected for in humans, but that the selection in question was sexual selection. The idea here is that individuals with larger brains are handicapped – that big brains did not lead to survival advantages, but that individuals who could survive and approach females despite having big brains had better genes than individuals who couldn’t develop such an impressive metaphorical peacock tail. The brain as a costly/wasteful signalling device indicating that you have good genes. It makes sense, but it’s speculative. Brain tissue is metabolically very expensive and judging from the archaeological evidence our ancestors didn’t do a lot with it during most of the time humans have evolved, something which I’ve remarked upon before here on the blog – I find this behavioural gap quite interesting, as do a lot of other people. What we like to think of as ‘human culture, a consequence of our large brains’ didn’t really happen until brains had pretty much stopped growing. Of course that doesn’t mean bigger brains didn’t lead to some advantages back then which we can’t observe now, but at the very least you have an evidence problem.

      A big problem is also that if our big brains conferred ‘classical Darwinian survival/reproductive advantages’, you’d expect other animals to be doing or have done the same thing we have done. Why would only humans benefit from having large brains? That line of thinking easily leads to some human exceptionalism tale which doesn’t really explain anything. Miller argues that sexual selection as the driving mechanism works well when it comes to explaining why other species haven’t gone the same route we have; sexual selection (referring, remember, to how selection is shaped by mating choices, rather than other factors) processes are very unpredictable and can run in a lot of different directions given similar starting points, which is a good thing because that’s the sort of process we’d prefer – on the other hand we don’t want intelligence to be all that advantageous in the classical sense (if it were a lot of other species ought to be very smart as well, and they’re not).

      “they describe well a world where you can assume (or you observe) many agents that display little variance in their characteristics and behavior/preferences” – regarding trait variation one thing you need to remember here is that traits which do not vary much are likely to have been subject to strong (classical) selective pressures. But traits subject to sexual selection would be expected to display a lot of variation still. It’s actually an interesting question if human cognitive abilities display large variation or small – it’s not something Miller has discussed, he takes the large variation viewpoint for granted, presumably because it fits better with his theory, but I actually believe you can argue either way. Given the modern framework with complex societies, the need for a successful analyst to understand stuff like Bellman equations, etc., you could argue there’s a lot of variation, sure. But compare pretty much any human being (with 46 chromosomes) with a chimp and you’re likely to get a different picture of the variation in cognitive ability. Which scale is the optimal one to apply? It sort of depends on what you’re interested in – though I’ve tended to think of this aspect as one of the potential problems with Miller’s theory. Anyway, interindividual or intergroup trait variation (and preference heterogeneities associated with trait variation) are important in evolutionary biology, and a lot of the models that are used are derived from/related to microeconomics and game theory, not macro. I believe there’s a tendency to want to explain too much and so the theories don’t sufficiently impose restrictions on the data, but the main problem is not of the type ‘assume a representative agent…’

      Do note that the period we’re experiencing now – with advanced culture, religion, complex societies etc. – are of limited use to evolutionary biologists in the sense that the selection pressures that made us who we are and the selection pressures that rule today’s humans are potentially very different. People like Miller are aware of this and they know a bit about just how things used to be different (though less than they’d like) and which consequences those differences may have had.

      Comment by US | August 27, 2013 | Reply

      • Incidentally, regarding this: “I’d expect that in humans (not necessarily, or likely, in other species) survival, or long life, would have a high correlation with status, wealth, and wisdom/experience (proxy for intelligence?).” Here’s also a quote from the book: “Evolutionary psychology has rightfully emphasized the strong male human interest in young female bodies, but I think its scope should be broadened to include the romantic interest aroused in both sexes by mature, worldly minds.”

        I laughed when I first read that sentence, probably because if I had to judge from personal experience I’d have to conclude that pursuing a life of the mind seems to be one of the safest conceivable ways to make sure you’ll die unloved, alone, without children. But of course that’d be a silly conclusion to draw, for many reasons (some of which I’ve implicitly briefly touched upon above).

        Comment by US | August 27, 2013


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