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They are tiny eight legged mites, related to spiders and look rather like an ice cream cone with stubby legs at one end.
Yet although you may not recognise, scientists say they are living on your face right now.
A new study found the mites, invisible to the naked eye, in 100% of the people they tested.
D. brevis is slightly shorter and rounder, and spends most of its life nestled deeply inside a hair follicle sebum (oil) gland.
Our skin is home to two different species of mites: Demodex folliculorum and Demodex brevis.D. brevis is slightly shorter and rounder, and spends most of its life nestled deeply inside a hair follicle sebum (oil) gland. D. folliculorum live more shallowly in the hair follicle
Called Demodex, they live in our hair follicles, buried head-down, eating the oils we secrete.,
Human faces host two species of mites -- Demodex folliculorum and Demodex brevis -- and they aren't that close of relatives.
Megan Thoemmes, a graduate student at North Carolina State University, told NPR. 'They're actually pretty cute.
'With their eight little legs, they look like they're almost swimming through the oil.'
'It's like having friends with you all the time,' Thoemmes says.
'Realizing that everyone has them and they're likely not causing any problems, it's pretty reassuring.'
In DNA tests of 29 people, 100 percent of those over age 18 carried DNA from Demodex mites, the team found in their study in the journal PLOS One.
Tests on more people have also come up with the same 100 percent number, Thoemmes says.
Scientists don't know how the mites spread among humans; one theory is that they're passed on from mother to child while breast-feeding.
Young people are much less likely to have them, while they've been found on almost all cadavers.
The mites probably crawl on our faces at night, when it's dark.
D. folliculorum live more shallowly in the hair follicle
Demodex have likely been living with us for a long, long time; as early humans walked out of Africa and found their way around the globe, the researchers say.
They found that mites from China are genetically distinct from mites from the Americas. East Asians and European populations diverged over 40,000 years ago and so far it looks like their mites did as well.
'Demodex have likely been living with us for a long, long time; as early humans walked out of Africa and found their way around the globe, they probably carried their mites with them,' said Michelle Trautwein, adjunct assistant professor of entomology at NC State and Schlinger Chair of Dipterology at the California Academy of Sciences.
'So we want to know if Demodex DNA can provide a reflection of our own evolutionary history by allowing us to retrace those ancient paths of human migration.
'One of the most intriguing (and unsolved) face mite mysteries is how humans acquired these beasties.
'Perhaps these mites are a model system of co-evolution. It’s possible that as every species of mammal evolved, so did their mites – each one particularly adapted to its changed environs.'