For the tiny mites that live on our faces, choosing a landlord may be a family matter.
Researchers identified four lineages of microscopic Demodex folliculorum mites living on the foreheads of 70 volunteers. People with different geographical ancestry hosted different mixes of mites. Participants of Asian and European descent harbored fewer types of mites than people with Latin American and African ancestry. The differences probably reflect historical patterns of human migration, the researchers report December 14 in the Proceedings of the National Academy of Sciences.
Within families, parents and adult children tended to share mites with similar genes, indicating that D. folliculorum is spread by close physical contact.
Mites may have evolved alongside their hosts for millions of years, the researchers suggest. These facial occupants could be used to study the global travels of ancient humans.