Great lice debate comes to a head 17:31 13 September 04 Exclusive from New Scientist Print Edition. Subscribe and get 4 free issues. A new genetic analysis may finally settle the question, and even help when it comes to getting rid of the little parasites, which are staging a comeback in rich countries. Linnaeus named the human louse Pediculus humanus in 1758, but later realised there might be two sorts. Debate has gone on ever since. Those who regard body lice as a separate species point out that they are bigger than head lice and live in clothes rather than...