Economics blogger Tyler Cowen of Marginal Revolution reviews Joan Roughgarden’s The Genial Gene: Deconstructing Darwinian Selfishness. And while he’s not convinced (a libertarian economist probably wouldn’t… and if he’s going to be consistent maybe shouldn’t be) he’s impressed.
The book rejects the “Red Queen” hypothesis for why there is sex (e.g., outracing parasites by frequently rolling the genetic dice) and presents a “portfolio diversification” view:
“The explanation for why asexual species keep popping up and quickly dying compared with sexual species would seem to be completely explained by thinking of asexual species as genetic versions of get-rich-schemes and of sexual populations as genetic versions of long-term mutual funds, without any need to invoke cost-of-meiosis considerations.
In other words, sex brings a genetic diversity which protects against rapidly changing environmental conditions and thus favors parental genes.
The author also argues against signaling theories of the peacock’s tail and against sexual selection more generally (especially on that latter topic I was not convinced but the discussion of sexual dimorphism and why it doesn’t always hold is nonetheless interesting). She presents “social selection” as an alternative and if you turn to pp.237-8 you will see an excellent page-and-a-half summary of what the book is about. Male promiscuity, for instance, is viewed as a genetic “tactic of last resort.”
Recommended, but with caution. It is a must for anyone who reads about evolutionary biology and by the end of the book I was less skeptical than when I started it.
Not being either an economist or a biologist (but having studied social theory and the history and philosophy of science) I’m less wary that Cowen… and possibly less certain that Roughgarden sounds from various reviews. Like nurture vs. nature debates the question of whether there is or isn’t sexual selection in species is sort of like debating whether sunlight or the fire heats a room with windows and a fireplace. The commonest answer is often “it’s complicated.”
It’s unlikely that no sexual behavior (i.e. mate-attracting or rival-repelling) is selected for. But it’s really unlikely that, as ev-psych people too often imply, that everything behavioral (women preferring symmetrical men’s wallets when they’re ovulating — the wallets, not the women… or something like that) and many things non-behavioral (women evolved big boobs because men can’t do rear-entry sex but needed something that looked like buttocks — the men, not the boobs… or something like that) is sexually selected for.
The point being that even if Roughgarden’s work were no more well-founded than the average ev-psych “report” it would still be a useful corrective because it strengthens the case for “it’s complicated.”
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Note: it’s surprising how many reviews include a disclaimer along the lines “Roughgarden believes in evolution, she just doesn’t…” I mean duh she believes in evolution. It’s rather well-established. Not believing the persistently biased, background-noise-ridden, poor-statistically-sampled, and tradition-reinforcing, and behaviorally extremely complex blather of the kind of ev-psych that gets coverage in the press** has nothing to do with not believing in evolution.
Update: The bit about male promiscuity being a last resort rings true. At least in non-herd animals. (I dunno, maybe it works for elk and elephant seals.) As I mention here, if women are all so sure-fired dependent on keeping men around to help raise offspring then it stands to reason that partners of promiscuous men are not going have men around to help raise those offspring… in which case (assuming, remember, that the grand theory was true) the offspring of such unions wouldn’t themselves be likely to survive to reproduce… let alone pass on their promiscuous father’s genes for, well, promiscuity. So sure, as a reproductive last resort male promiscuity might work. But in general, over the multitudes of generations required to establish such traits, I don’t see it.
[** i.e. not the kind of evolutionary psychology that understands that’s methodically and actually scientifically learning to crawl before it can do circus tricks. —fl]
Submitted by 2813 (not verified) on Wed, 2009-04-01 14:45.
I somehow thought that promiscuity in an evolutionary sense was because most early societies of humans didn't favor monogamous relationships and that male tendency still existed even though society now prefers monogamy.
About that boob thing; that's cultural.
Submitted by 2813 (not verified) on Thu, 2009-04-02 00:09.
I seriously doubt "it's cultural" is an adequate explanation for the size of womens' breasts. Other primates do not have conspicuous breasts unless they're lactating; the males of most primate species are actually turned off by the sight of breasts (with at least one odd exception in orangutans, who sometimes prefer human women with conspicuous breasts to females of their own species. Or even sometimes human women with conspicuous tattoos.) and often cheat on their mates while they're in the lactating stage (assuming regular pair-bonding).
Since humans are primates, and not closely related to Orangs, and there's actually a minor physical cost to having conspicuous breasts at all times, there must have been some sort of evolutionary advantage at some point for the switch to full-time breasts and a general male preference for them, but nobody has yet come up with an adequate reason.
Unless you meant a male preference for "larger than average breasts", in which case it's probably at least partly cultural, and one of us misunderstood what Figleaf meant.
[See, that's the thing -- Orangs, which are interested, are more distant than other primates that... aren't... or are even averse. Which says... if it's expressly instead of opportunistically about sexual selection it's complicated. I mean, yes, humans have much bigger breasts even when not lactating so there's something going on. We've just differentiated so rapidly it's not clear whether it's specifically selected for or a consequence of selection for some other characteristic. (Consider the author's point that it's not male hormones that make peacock feathers so gorgeous, it's female hormones that make them drab and difficult to see -- suggesting it's not selective pressure on males to be distinctive, though there must be some, but pressure on females to be less visible while nesting.) Culturally speaking it's certainly the case that breasts aren't universally considered erotic, and I'm sure you'd find at least one non-fluke group that considered them unpleasant and off-limits.
Submitted by 2813 (not verified) on Thu, 2009-04-02 15:21.
I was not giving an alternative to an evolutionary reason why women have protruding breast. I was saying that not every culture think of them as a major turn on. It is also the times too. When I was small it was not uncommon for women to nurse in public and they didn't smother the baby doing it.
Brazilian women have their breast reduced more than enhanced, it's the booty for them. Have you heard of women having the Brazilian lift on their butts? It is almost shameless if you are of African decent and have no butt.
Submitted by 2813 (not verified) on Thu, 2009-04-02 17:02.
I was think about it a bit more later, and realized that whatever the evolutionary advantage was, it probably had to do with hormone levels than anything else - possibly something that helped store up body fat during the ice age, or something similar. Those men who happened to prefer women with the obvious, visible effects of those genes had more surviving children. Since there was no strong pressure to revert after the ice age (or whatever it was), the rest... is prehistory.
The preference probably isn't quite as strong as it was, and culture can do a lot to alter, enhance, or derail instincts (especially since instincts in humans are often kind of weak to begin with). So it's not surprising that there are are some cultures which mostly ignore them in preference to other portions of the anatomy. And there probably are some that are even adverse, but I'd suspect that they're at least as rare as cultures with Object-Verb-Subject order languages. (Even in regions where there are a wide variety of word orders among the languages, OVS is absent or nearly so, suggesting that this is somehow mostly unnatural for humans.) I do strongly suspect that there is a natural preference for breasts, at least as a mild general tendency if nothing else.
Note: In the case of African and Brazilian women, there is a small but significant portion of the population who have breasts that are simply too big - and cause health problems for the woman, which is part of the reason for the large number of breast reductions. And for the buttocks thing, well, that's usually number two in the cultures which put more emphasis on the bosom, and there are a wide variety of cultures in the world... and yet ultimately there are always men who prefer things which are outside the cultural standards, plus breast and buttock size usually matter slightly less than hip-to-waist ratio, which few cultures specifically express a preference for.
So yeah, it's *really* complicated.