Tiny Mites Living on Your Face Hold the Key to Your Ancestry

http://www.takepart.com/article/2015/12/14/tiny-mites-live-your-skin-hold-key-your-ancestry

When people talk about wildlife, they’re generally thinking about wolves running through forests, or maybe squirrels skittering about neighborhood trees. But let’s look a bit closer to home: Blink. Wildlife just took a ride on your eyelashes. If that makes you lift your eyebrows in puzzlement (or dismay), well, there are animals in your eyebrows, too.

In fact, your face is an ecosystem of long standing for two species, which have been passed on for generations in your family. They probably climbed aboard while you were nursing at your mother’s breast. Demodex folliculorum has evolved to live in human hair follicles. Its cousin Demodex brevis ensconces itself slightly deeper in the microhabitat of your sebaceous glands.

Follicle mites, as they are commonly known, are distant relatives of spiders. They eat our dead skin cells, or maybe the oils, bacteria, and fungi on our skin, and they are, I should quickly add, utterly harmless. It’s even possible they perform some sort of housekeeping service, making us mutually beneficial: We give them habitat, they minimize zits. But no one really knows for sure. In any case, mites have coevolved with humans and prehumans for millions of years.

A study released Monday in Proceedings of the National Academy of Sciences suggests that mites may also provide a sort of skin-deep view of our genealogy and shed new light on the history of human migration. Bowdoin College evolutionary biologist Michael Palopoli and his coauthors sampled follicle mites from 70 individuals, using the standard technology in the field: They scraped a bobby pin across the forehead of their test subjects. Then they analyzed the scruffy material trapped in the crook of the bobby pin.