What lice have to say about human evolution

From the International Herald Tribune: Head-scratching puzzle: What lice have to say about human evolution.

One of the more embarrassing mysteries of human evolution is that people are host to no fewer than three kinds of louse while most species have just one. (…)

Louse specialists now seem at last to have solved the question of how people came by their superabundance of fellow travelers. And in doing so they have shed light on the two major turning points in the history of fashion — when people lost their body hair, and when they first made clothing. [continue]