Evolution in Action

The Economist magazine has an interesting article on the evolutionary tradeoff between big muscular men and smaller healthier men. Here is the key bit:

Their data came from the National Health and Nutrition Examination Survey, which followed 12,000 American men and women over the course of six years. They found that men require 50% more calories than women do, even after adjusting for activity levels, and that their muscle mass is the strongest predictor of their intake of calories—stronger than their occupation or their body-mass index (a measure of obesity). And there is another cost to being muscly: men’s immune systems are less effective than those of women (which was known before), and become worse the more muscular the men are (which was not).

The benefits, however, were there, as well. The more muscular a man, the more sexual partners he reported, both in the past year and over his lifetime, and the earlier his first sexual experience was likely to have been. This may, in part, be a result of the ability of muscular men to intimidate 97lb weaklings. But in a society where extreme forms of such intimidation are curbed by law, female choice seems as likely an explanation—especially as previous studies have confirmed scientifically the everyday observation that women do indeed prefer men with big biceps and triangular torsos.

Because muscles come at such cost, Dr Gaulin thinks an evolutionary fight is going on between natural selection, which conserves metabolic expenditure and promotes longevity, and sexual selection, which willingly trades both for extra mating opportunities. This may explain why men have such a range of muscularity. In the past, the strong man would have had better mating opportunities in the short term, but the skinny guy who outlived him could have had just as much reproductive success over the course of his longer life.

I wonder how clear-cut the trade-off is. I'm a fuzzy gray kind of fellow. I think there are most likely many more factors involved.

One reason why these "announcements" of discoveies get retracted is because the investigation is too limited and too simplistic. I tend to be skeptical about reserach findings that paint things in such a black-or-white format.

I can buy that there is an evolutionary trade-off going on because I believe that evolution is very active. (When I was a kid the consensus was that evolution happens over very large time scales and that humans had stepped outside the environment in which evolutionary pressures would continue to shape us.) So I enjoy the basic story of this "discovery", but I doubt that the proper interpretation is as simple as presented.

Here's another example of jumping to a conclusion from a bit of experimental results. Again, from an Economist magazine article:

Hormones, not sexism, explain why fewer women than men work in banks

That the risk-taking end of the financial industry is dominated by men is unarguable. But does it discriminate against women merely because they are women? Well, it might. But a piece of research just published in the Proceedings of the National Academy of Sciences by Paola Sapienza of Northwestern University, near Chicago, suggests an alternative—that it is not a person’s sex, per se, that is the basis for discrimination, but the level of his or her testosterone. Besides being a sex hormone, testosterone also governs appetite for risk. Control for an individual’s testosterone levels and, at least in America, the perceived sexism vanishes.

Whoa! First of all, when I was a kid the financial industry was not presented as a "high risk arena". Instead it was presented as an area of cautious investment. Maybe that was a consequence of the reverberations of the Great Depression. I can agree that by the 1980s the financial arena was presented as a testosterone-filled arena of high stakes risky behaviour. But is that finance? Isn't that just a cultural deviance that grabbed hold of an era and sent it off on a wild and disasterous ride? The article never asks the question "what role does risk-taking play in finance?". It simply assumes that the more joy in risk-taking you have, the better "adapted" you are for a finance industry job. That is quite a leap.

At least one person I know doesn't think risk-taking is synonymous with finance. Here's a bit from an op-ed in the NY Times by Paul Krugman:

Thirty-plus years ago, when I was a graduate student in economics, only the least ambitious of my classmates sought careers in the financial world. Even then, investment banks paid more than teaching or public service — but not that much more, and anyway, everyone knew that banking was, well, boring.

In the years that followed, of course, banking became anything but boring. Wheeling and dealing flourished, and pay scales in finance shot up, drawing in many of the nation’s best and brightest young people (O.K., I’m not so sure about the “best” part). And we were assured that our supersized financial sector was the key to prosperity.

Instead, however, finance turned into the monster that ate the world economy.

The message is: always be skeptical of popular science interpretations. Worse, always be skeptical of new scientific "results".