Lice aren't nice, at least not when they're attached to people. In a bid for scientific respectability, however, these pestering parasites may have yielded provocative new genetic insights into human evolution.
Head lice found on people today consist of two lineages that diverged about 1.18 million years ago, say biologist David L. Reed of the Florida Museum of Natural History in Gainesville and his colleagues. Analyses of mitochondrial DNA, inherited solely from the mother, indicate that the group that includes body lice evolved with the ancient Homo species that became modern Homo sapiens, the researchers contend. This genetic category of lice now inhabits all regions of the world.