While women with curvy figures might enjoy more attention from men in Western culture, and find it easier to become pregnant, new research suggests they may also face some evolutionary disadvantages compared to women with thicker waists.
That's because the same hormones that increase fat around the waist can also make women stronger, more assertive, and more resistant to stress, according to a new study published in the December issue of Current Anthropology.
Given those findings, it makes sense that the slim-waisted body has not evolved to become the universal norm, said the study's author, Elizabeth Cashdan, an anthropologist at the University of Utah.
Her study takes aim at a theory popular in evolutionary psychology and medicine: that men universally prefer women with narrow waists and larger hips because their higher levels of estrogen make them more likely to conceive a child, and less vulnerable to chronic diseases. These preferences, the theory goes, have defined women's ideal body shape over time.
One of the most tiresome aspects of evolutionary psychology is the paradigmatic straitjacket which many of the practitioners operate under; the only type of evolution that exists is unidirectional. Deviations from expectation are explained away. The importance of human universals mean that variation can not exist. These sorts of evolutionary psychologists resemble the caricature of the economist who holds to rational choice so that behavior which deviates from the model is explained by ad hoc contingencies. The most popular current expositor of this view of evolutionary psychology is Satoshi Kanazawa, who is also not a big fan of statistics. In any case, the paper will come out in Current Anthropology, but isn't on the website, but there is a press release:
Androgens, a class of hormones that includes testosterone, increase waist-to-hip ratios in women by increasing visceral fat, which is carried around the waist. But on the upside, increased androgen levels are also associated with increased strength, stamina, and competitiveness. Cortisol, a hormone that helps the body deal with stressful situations, also increases fat carried around the waist.
"The hormonal profile associated with high WHR (waist-to-hip ratio) ... may favor success in resource competition, particularly under stressful circumstances," writes Cashdan. "The androgenic effects--stamina, initiative, risk-proneness, assertiveness, dominance--should be particularly useful where a woman must depend on her own resources to support herself and her family."
In other words, trading the benefits of a thin waist for better ability to collect resources may be a good deal in certain societies and situations. And there is evidence that male mate preferences may reflect this trade-off, according to Cashdan.
In Japan, Greece and Portugal, where women tend to be less economically independent, men place a higher value on a thin waist than men in Britain or Denmark, where there tends to be more sexual equality. And in some non-Western societies where food is scarce and women bear the responsibility for finding it, men actually prefer larger waist-to-hip ratios.
In Demonic Males Richard Wrangham reports that orangutan males come in two morphs. A very large one, and a small one which seems to be a case of paedomorphism. Female orangutans prefer the normal large male orangutans as sexual partners. But the small ones do reproduce. How so? They ambush and chase the females and rape them. This is a behavioral strategy which can work well if the small variant morph is not extant as too high a frequency, because females will then not be "on alert." How these sorts of variations emerge is clear to anyone who is cursorily familiar with evolutionary game theory.
I use the orangutan "raper" strategy as an example for a reason: some of the press will no doubt spin the new research as a victory for feminism and a rebuke to heteronormative males or something of that sort, at least implicitly. But the intersection of biology and behavior is fundamentally value neutral; humans are the ones interjecting norms. The old paradigm of evolutionary psychology, which I must admit is \ "Just So" and rooted in a coarse and outdated understanding of biological science, should be rejected on scientific grounds. Not only are there many areas where it offers little insight, but it is no longer compelling on theoretical grounds.
There are certainly a core of human behavioral traits which exhibit little variance, and are extremely constrained by purifying selection which fixes the trait so that only one morph is extant at appreciable frequencies. But there are many which no doubt exhibit continuities, while a fair number likely can be modeled as discrete strategies across the adaptive landscape, buffeted by stochastic & frequency dependent dynamics as well as exogenous parameters. As simple as sufficient, but as complex as necessary, should be the maxim.
A very large one, and a small one which seems to be a case of paedomorphism ... This is a behavioral strategy which can work well if the small variant morph is not extant as too high a frequency
The small orangutan seems to just be in an arrested state of pubescence. All big orangutans start as small orangutans, and all small orangutans turn into big orangutans in captivity.
In the wild it is believed that once the small orangutan is able to defend a territory for some given period of time without a big male randomly chasing them away, this is what triggers the second stage of development (affordable family formation??). This is why they always finish growing in zoos.
Actually, this study makes me think of my own culture and several others where if your horse dies, the husband hitches his wife to the plough. Women in lots of anti-feminist cultures are expected to be workhorses, in a lot more ways than reproducing--women in my family are not considered "good" women unless they do 100% of the housework, child-rearing AND farm work. And find time to embroider their husband's undies, too, or something. Men are nevertheless considered more valuable even though they do demonstrably less economic work.
I think the researchers ain't looking right. They should have a look at rural farm communities if they want to see deliberate selection of thick-waisted women: You can't manage 4000 lbs. of draft horse, 100 head of dairy cattle, three farm dogs and a passel of brats without some assertiveness and coping skills, and the value of a "good" woman in those societies is placed more highly on cooking skills and being able to lift a pig under each arm than on T&A. To my family's eyes, the thin-waisted women need a burger.
Russian male peasants are a good example here: their traditional ideal mate was curvy women earlier in life (teens, early twenties) who *became* non-curvy callus-handed workers as they aged. This seems to have selected for a peculiar trait in Russian women: they go from this to this very quickly.
So this goes to show that it's not either or for selection. It could be that this trait of non-curvy waists was only preferred because it emerged later in development (late twenties or thirties). Russian women are an extreme example of this, but it appears to be the trend; women get more masculine, less curvy, and harder working as they age.
Slightly afield, but you might find interesting this politics of sociobiology
Lora, your comment reminded me of something Peter Frost wrote.
Interesting article TGGP. The bit where he wonders why, therefore, men aren't programmed to find hard-working women "enjoyable" seemed a little bit far fetched to me; isn't it sufficient for selection that hard-working women increase one's chances of the offspring having enough food to eat?
Some of the questions raised in the Peter Frost article reminded me of a Neil Gaiman story, The Monarch of the Glen. The hero meets a hulder, a Norse woman who is half-demon, sort of thing--very strong, hard-working, but a bit temperamental. She tells him how once she fell in love with a farmer who abused her, beat her daily, and she put up with it for years. Finally, on a particularly bad day, the hulder picked up a heavy iron poker and bent it into a perfect circle with her bare hands. The farmer realized that any time he had beaten her over the years, she could have turned around and done the same to him, and so he never said a cross word to her after that day. The hulder's question to the hero, then, was why did she stay with the guy who abused her? It didn't make sense.