Last week I pointed to a really stupid story in the Times (UK): "Women are getting more beautiful". Once upon a time, I had a reader complain that I called the New York Times, just the Times, since the real Times is based in London. I often chuckle when I remember this, because the science coverage in the "real" Times is so abysmally bad. As with everything, there are occasional bright spots, but in this case the low spots are pert' near looney-tunes bad. The "Women are getting more beautiful" story was definitely a low spot.
Turns out, the author of the study agrees -- and he has a webpage where he strikes back at the story! Markus Jokela writes:
Having your study publicized by the media is nice. Having your study misrepresented and misinterpreted in the process is not. The media coverage of my paper on physical attractiveness and having children had a bad start and even worse follow-up. The origin of the problem: Times Online news article sexing up the finding a bit too much (I wasn’t interviewed for this article at all and heard about it only after it had been published). Then things got worse with other journalists copying & slightly modifying the Times Online piece. Naturally, things were further muddled by the If-I-were-a-movie-critic-I-would-rate-movies-without-seeing-them-and-just-by-relying-on-discussions-overheard-in-a-pub columnists, the I-haven’t-read-the-paper-but-here’s-my-take-on-it-anyway bloggers and the ever so alert This-research-is-nonsense-I-want-my-tax-money-back-even-if-the-research-was-not-funded-by-my-tax-money readers.
I love that last sentence with all the hyphenates. Also, the one I pulled for the title of my post:
And please, do not refer to me as the “Ann Coulter-loving scientist”, I hadn’t even heard about the lady before the headline.
One interesting thing:
So how much is 0.02 standard deviations? Perhaps it helps to consider the effect magnitude in another context: if natural selection were to favor tallness with the same strength as observed for attractiveness here, height would increase by ~0.20cm (or 0.08 inches) per one generation. Such a slow process would be observed only over several generations, say, at least 5-10 generations to get an observable effect. In other words, the finding says nothing of comparison of people’s attractiveness in the 1950s vs. the 1970s vs. the 2000s!
The media always want to put things in the terms of the last and next generations. That's understandable -- most of their readers couldn't care less about people 100 years ago, much less 1000 years ago. But in this case, although Jokela says the selection is "weak", it would actually be pretty strong in evolutionary terms. He's talking about a 16 percent reproductive advantage for women in the second-highest "attractiveness" quartile. One standard deviation in 50 generations (or two in 100 generations) would be abrupt change.
Human craniofacial phenotypes have been changing, but across the last few thousand years I wouldn't say it's been as fast as two standard deviations per 100 generations. So that raises an obvious question: Why are things different today? And if we like to mate with the beautiful so much, why is "attractiveness" still heritable?
Recent differential reductions in fertility in the sampled population, changes in other social correlates of mating success (like physical labor, or family wealth), alterations or oscillations in judgements about attractiveness, unobserved epistatic associations with attractiveness, social effects of media stereotypes -- there are a dozen or more obvious hypotheses. Don't start counting your future Eloi chickens before they've hatched.
But next time somebody asks you whether human evolution is stopping because of the low mortality rates in industrialized economies, here's a pretty clear example to the contrary. Low mortality only decreases one component of selection -- relaxing this component leaves fertility selection unchecked. Relaxing mortality may even change the vector on some fitness associations.
(via Gene Expression)
References:
Jokela M. 2009. Physical attractiveness and reproductive success in humans: evidence from the late 20th century United States. Evol Hum Behav (early online) Abstract
