A controversy over lice that has had zoologists scratching their heads for almost 250 years has been resolved at last, a report in next Saturday’s New Scientist says.
The squabble dates back to 1758, when Carl Linnaeus, the father of the taxonomic system for classifying organisms that remains with us to this day, declared there was one species of human louse, which he boldly baptised Pediculus humanus.
Linnaeus then became racked by nit-picking doubt, sometimes agonising that there might in fact be two species of human lice, not one.
The debate has raged ever since.
Backers of the two-species theory point out that body lice are bigger than head lice and live in clothes, rather than in head hair.
Body lice can also transmit diseases such as typhus and trench fever, something that head lice have never been known to do.
One-species advocates say that, in lab conditions, head and body lice can interbreed, which means they must be the same species.
However, breeding in artificial conditions is a poor test of a species.
Genetic detective work, using 100% guaranteed wild lice, has now found the answer.
DNA fingerprinting of 443 head and body lice, collected from seven boys in Nepal and four girls in Inner Mongolia, showed ”two genetically distinct populations”, the British scientific weekly says.
Despite this, there is still room for a fresh spat — for the next challenge will be to agree on names for the two species… — Sapa-AFP