In 1841, German anatomist Jacob Henle was examining earwax under a microscope when, much to his surprise, tiny, worm-like creatures came into view. Soon after, scientists realized that these animals were, in fact, tiny arachnids. And now we know they belong to a group of mites, which scientists named Demodex, that contains more than 100 different species that live in and around mammals’ hair follicles. Two of these species Demodex folliculorum and brevis specifically inhabit human follicles. And not just some people’s. Nearly everyone is thought to host mites from at least one of these two Demodex species. One person’s face might harbor hundreds or even thousands of individual mites. So, yes: on any given day, microscopic arachnids are probably eating, mating, and laying eggs inside your pores. So, is this... okay?
Many might mysteries remain in part because of how difficult it is to keep Demodex alive and investigate them off our skin but scientists have begun teasing out the truth. And it turns out that our entanglement is probably just about as old as we are. It seems that the mites’ ancestors developed and diversified alongside mammals, moving into their pores and feeding off the oily secretions in their host’s follicles. Then, we humans eventually came about, with our very own follicular mites to accompany us, and we’ve been inseparable ever since. Babies seem to inherit Demodex mites through direct contact, like during birth and breastfeeding. And a person’s mite population tends to grow after puberty, probably in response to changes in our hormones, oiliness, and immune responses. The mites mostly reside on our faces, especially our noses, where our pores and oil glands are larger. They take approximately one week to reach adulthood and spend the remainder of their lives about another week either face-down in our pores or traversing the expanse of our faces. As you might expect, based on the fact that they are usually embedded within our skin, our daily routines are pretty tightly synced. Around dusk, our bodies secrete the hormone melatonin, which helps prime us for sleep. For Demodex, however, melatonin is thought to serve as their stimulating nocturnal cue. So as night falls and we become less active, our resident Demodex mites liven up. In fact, because they're regularly tucked away in our pores or out exploring in the dark, they've lost the genes that give them UV protection altogether. Over the course of an evening, some adults shimmy out of our pores in search of mates, moving at speeds of around one centimeter an hour across our facial terrain. And then they pop back into our pores to lay their eggs. Scientists estimate that one pore can hold a family of around 14 mites. Demodex are on virtually everyone’s faces including those with healthy skin and little inflammation. It seems that Demodex mites are only associated with skin issues in cases where some kind of immune dysfunction is at play like when someone’s immune system reacts strongly to the mites’ presence or doesn't adequately suppress their populations, all of which can cause inflammation. For most people, however, follicular mites are harmless. And most people maintain their original mite lineages, even as they travel or move to new parts of the world. What’s more, it seems that different lineages of mites evolved alongside different populations of people, so scientists may be able to tell your ancestry by merely studying the mites that colonize your face. Because mite populations stick with one person, however, they have limited breeding opportunities, which reduces their overall genetic diversity. This might have set our follicular mites on a path for extinction, but that would be a long ways off. In the meantime, you can look at yourself in the mirror and rest assured that your face is, in fact, teeming with a multitude of mites. And with that, nighty night and sleep tight.
Thank you....
Comments
Post a Comment