By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) - Head lice taken from 1,000-year-oldmummies in Peru support the idea that the little creaturesaccompanied humans on their first migration out of Africa,100,000 years ago, researchers reported on Wednesday.
Genetic tests showed the lice are nearly identical tostrains found around the world that have been dated to whenhumans first began to colonize the rest of the world.
"It tells us that this genetic type got around the globeright as humans spread and migrated around the globe," saidDavid Reed of the University of Florida, who worked on thestudy.
"We know that this parasite was distributed all over theglobe along with us," Reed said in a telephone interview.
Writing in Journal of Infectious Diseases, Reed andcolleagues noted that there are three known strains, or clades,of head lice -- A, B and C.
Clade A is found everywhere, clade B is common in bothNorth America and Europe, and clade C is rare. There had been atheory that clade B evolved separately in the Americas and thatEuropean explorers carried A to the Americas and brought B backto Europe with them.
Reed, who showed in 2004 that clade A dated back to earlyhumans, said he got to test the idea by accident.
The lice were collected off the heads of two mummies foundin the southern Peruvian coastal desert. "The mummies belongedto the post-Tiwanaku Chiribaya culture," the researchers wrote.They were dated to around 1000 AD.
The two heads, removed from the bodies by looters yearsbefore, had elaborately braided hair. Researchers collectedmore than 400 head lice from one and 500 from the other.
"They were loaded. It was amazing," Reed said. "It reallywas remarkable how lousy they were."
He speculated that the elaborate braids would not allow forregular combing, thus making a haven for the little parasites.
Reed was able to get intact DNA from the lice andsequencing showed they were all clade A.
That means the strain was distributed across the Americashundreds of years before the first Europeans arrived.
Reed believes he can use gene sequencing of lice to trackand date human migrations all over the world.
Type A lice include both head and body lice. Thebloodsucking creatures can only live on humans -- they die veryquickly away from their hosts and cannot survive on any otheranimals.
They can also transmit diseases such as typhus. Reedbelieves some mummified lice will carry the rickettsia bacteriathat transmit typhus, and gene sequencing of these bacteria canalso help trace routes of human migration.
It is also possible to test the theory that typhus was aNew World disease carried back to Europe by explorers, Reedsaid.
(Editing by Stuart Grudgings)
