This article is a bit disgusting but remains fascinating as well.
Demodex folliculorum is a species of mite that lives in and around the hair follicles of humans and other mammals. Bowdoin College evolutionary geneticist Michael Palopoli and his colleagues sampled the DNA of these mites living on a diverse group of 70 human hosts. The mites’ mitochondrial DNA revealed different lineages that closely match the ancestral geography of their human hosts. One mite lineage is common among people of European ancestry, no matter where they live in the world now, and is persistent even after generations in new locations. Other mite lineages are more common among people of Asian, African or Latin American ancestry.
In other words, you apparently inherited your hair mites from your ancestors. Yuck!
Mining the DNA sequences of our faithful mite pals could also provide a new tool for scientists to trace ancient human migrations. “We’ve got these genetically diverse mite lineages existing on all of us, and that provides a wealth of information, potentially, for unraveling different human migration patterns,” Palopoli said.
You can read the full story by Brian Handwerk in the Smithsonian web site at http://goo.gl/7IhuKQ.