What Makes Humans Human?

The recent efforts to map various genetic characteristics of humans are beginning to yield insights into what makes us Homo sapiens at the most basic levels. John Hawks draws attention to a paper published this week in PNAS. The paper uses statistical analysis of the distributions of linkage disequilibria in single-nucleotide polymorphisms (SNPs) to detect genes under recent selection pressure, and finds that at least 10% of human genes have been under such selection. (The percentage is an under-estimate because the coverage of SNPs is skewed to higher frequencies.) Many genes under recent selection cluster into four main groupings: “host-pathogen interactions, reproduction, protein metabolism, and neuronal function”. That last, of course, is real interesting! They offer some tentative explanations for the groupings:

We outline several predominant biological themes among genes detected with this strategy and suggest that selection for alleles in these categories accompanied the major “out of Africa” population expansion of humankind and/or the radical shift from hunter–gatherer to agricultural societies .

See Hawks’ blog entry for a more discussion and the paper itself, which is free online.