At his blog West Hunter, Greg Cochran writes Natural selection is not an odd, unusual, poorly understood phenomenon like ball lighting. It is not something that last occurred 50 million years ago, like a kimberlite pipe eruption. And, of course, it applies to human behavioral traits, which are significantly heritable. Unless you think that the optimum mental phenotype (considering costs and payoffs) was the same in tropical hunter-gatherers, arctic hunter-gatherers, neolithic peasants, and medieval moneylenders (which would strongly suggest that you are an idiot), natural selection must have generated significant differences between populations. Differences whose consequences we see every day, and that have been copiously documented by psychometricians. This notion that ongoing natural selection is not the default – that it only happens on national holidays or whatever – is fairly common among biologists. Obviously untrue, because you can't even have things stay the same without ongoing selection – otherwise mutations and drift would gradually ruin everything. more... See more text