There are a pair of articles in this week’s edition of the journal Science that are almost certainly going to cause some excitement and controversy in the field of human evolution. Controversies in this area are nothing new, of course, but these articles seem to have all of the necessary ingredients for a spirited debate. They also seem to be almost certainly destined to be miscited by any number of unsavory individuals.
Although the two articles have slightly different sets of authors, both come from the same laboratory, and both focus on the same topic: natural selection acting on genes involved in the development of the human brain. Two different genes were examined, and in both cases specific versions of the genes - alleles - were found to be present in frequencies that indicate that they have recently been (or still are) the subject of strong selective pressure. In both cases, the alleles appear to be very new - younger than the appearance in modern humans. Finally, and here is the bit that’s going be the most controversial part of this, the selectively favored alleles are less likely to be present in people from certain geographic locales.