Microscopic mites that live in the pores of your skin use the oils you produce to fuel their “all night” mating sessions — which is actually a good thing. Once blamed for ailments like acne, rosacea, and itchy scalp, these nighttime lovers may not be keeping our pores clogged and free of the oils that contribute to bad skin problems.
Because the tiny mites do us more good than harm, they can be considered as much a part of our daily lives as the bacteria that live in our gut microbiome. But scientists at the University of Bangor and the University of Reading say their new research on the small Demodex folliculorum mites suggests that the existence of mites is threatened.
The first-ever study of the mites’ DNA has revealed that their ancient relationship with humans contributed to the loss of much of the organisms’ genetic variety. Living in the follicles on our faces and nipples — the mites’ preference, scientists say, although they can be found all over the body — has given them such an isolated experience that they are quickly approaching an “evolutionary dead end.”
With very little admixture of mites, mating pairs passed on the same genes for millions of years and shed the ones that weren’t needed. Because they can’t protect themselves from UV rays, the mites hide in your pores during the day and come out at night to eat and do their job.
At some point, the mites lost the gene to produce melatonin, the chemical nocturnal animals use to keep themselves awake at night. Fortunately for the mites, melatonin is produced by glands on our skin. It is this byproduct of our existence that the mites use to fuel their fertility.
Despite the mites’ relationship to us and other animals since mammals first appeared on Earth about 200 million ago, demodex are effectively on their way to extinction. Analysis of the mites’ genome has shown that they can only be passed from mother to child (so your mites will never mix with your partner’s no matter how many times you rub the face).
As generations come and go, the differences in the DNA of mites get smaller and smaller. One day the gene pool will be so small that they will become extinct.
The genetic analysis also dispelled a long-standing notion about the mites: that they have no anus and hold all their feces throughout their lives (a short two or three weeks) until they die. This dermo-dumping, as was once believed, could cause skin inflammation and problems such as acne. But the demodex mites do not deserve such a bad reputation.
“Mites have been blamed for many things,” said Dr. Henk Braig, co-lead author of the new study. †[But their] long association with humans might suggest that they could also play a simple but important beneficial role, for example by keeping the pores in our face loose.”
Although the mites were previously considered parasites, Braig and colleagues are pushing for a reappraisal of their role in our lives. Their help in keeping our skin healthy means we can think of them as one of our symbiotes – a lifelong collaboration between two different species that benefit both.
Can we prevent their loss? It may be too late.
“I don’t think we can stop nature, and we shouldn’t,” said Dr. Alejandra Perotti, co-author of the demodex Research. “However, [our] healthy skin should be enough to maintain a healthy population for generations to come.”
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