Wow, this topic seems to have the same heat to light ratio as discussions about nature/nurture and the gender gap in the sciences. It's pretty amazing the percentage of confident arguments for one side or the other that seem to be based on little more than personal ancedotes or what the author wanted to believe.
Anyway serious discussion of this issue should start with the
original paper (if you have access). A quick skim will reveal that it really doesn't offer much if any support for the evolutionary claim.
The study basically took a bunch of yearbook photos (from 1956) of people for whom they already had data about reproduction. They then asked participants in the "Madison Senior Scholars program" to rate the attractiveness of these yearbook photos (so presumably US HS or college students). They then observed that attractive women tended to have more children than unattractive women (though attractive women outproduced very attractive women).
This setup should make one very leary of drawing any deep evolutionary explanations for the observed phenomenon. Indeed the authors themselves point out that they can't draw any conclusions about mechanism and seem to suggest there are likely complex causes underlying the observations. Moreover,
the authors come right out and say the observed correlations between offspring gender and attractiveness aren't significant enough to warrant any conclusions. ("best interpreted cautiously before more data are available").
As far as reproductive success goes just off the top of my head I can come up with a whole bunch of hypothesizes that would account for the greater offspring effect.
- Yearbook attractiveness in 50s women reflects effort and hence priority they place on finding a husband/reproducing.
- Attractiveness is correlated to health/nutrition which correlates with more/easier births.
- Attractiveness is correlated to grooming habits learned in households with better socioeconomic status. This leads to more marriages.
- People tend to find people who look like their parents attractive so those sub-ethnic groups who have more kids tend to get rated higher
- Random correlations from a bunch of other factors (race etc..)
One could go on but what's the point. The study just doesn't say what this ridiculous piece of science 'journalism' claims it does.
However, that isn't grounds to reject the claim that humans have been evolving to be more attractive or even that physical attractiveness in women undergoes stronger selection pressure than it does in men. Presumably, one should think that at least the first claim was true (at least before birth control). Hell, it's pretty much a tautology (by definition more attractive means ceterus parabus people find you more sexually attractive). The second claim is less clear. After all in most animals it is the male which undergoes the greater pressure to look attractive. However, in humans there are plausible reasons to think that other forms of status for men take the place of purely physical status while the need for healthy births retains that pressure for females. Of course there are probably real papers on this with real evidence and who knows what that means in the modern enviornment.