I now see your point about the 26% differential and ugly dying out. Over a thousand generations that would certainly have taken place at those rates.

On the other hand, maybe our ancestors put us to shame in the ugly department and we’re the product of this weeding out process. As the evolutionary biologists say: It’s all relatives.

My earlier comment about ugliness dying out reflects this. I don’t see where the cost of beauty is, so any effect anything like 26% would select for beauty to such an extent that there would rapidly be no ugly people.

Perhaps I have answered my question above – if a result seems to be much larger than make sense, suspect the stats.

Thanks for posting this. Very interesting on several fronts.

Bottom line re: Kanazawa’s conclusions seems to be that his results are not statistically significant, only suggestive, and there’s only a snow ball’s chance in hell of obtaining a statistically significant result for such potentially small effects regardless of sample size.

This makes a lot of sense considering that, in this case, evolution working over 30,000+ years could be expected to exhibit only a small effect on current populations, too small to show up in statistical studies.

I think the assumption that beauty is more costly to produce (Ha! wouldn’t you expect that from an economist) is doubtful as a mechanism for natural selection. Why would beauty be more costly to produce? That cries out for a hypothesis.

I think the more plausible explanation is that all women compete for the healthiest and best-provider males (I think there’s some scientific evidence for this), and beauty bestows an advantage in that competition. If men place a higher priority on beauty (I think there’s evidence for this too; perhaps men conflate beauty and healthiness), natural selection would favor the production and survival of beautiful daughters and sons via the healthiness/better-provider genes of the male.

However, this does not fully explain either of the two observed results Kanazawa explores. That requires a different mechanism such as the “haggard mother” hypothesis combined with the assumption that some mothers tend to produce daughters while others tend to produce sons.

Competition in the womb is not the only venue for natural selection to have its way.

If we assume there are some women with a propensity to have daughters and others who tend to produce sons, then (1) the birth of more females than males (through the “haggard mother” mechanism) and (2) the higher propensity of beautiful daughter-producing girls to survive to child-bearing and to produce more children over their lifetimes, gives us a coherent theory to work with.

Over hundreds or thousands of generations these factors would result in the observed (1) propensity of beautiful women to have more daughters and (2) the difference in the proportions of beautiful women to beautiful men in the genral population.