It’s one of those supposedly useless parts of us that demonstrate the purported incompetence or nonexistence of design reflected in bodies, but the hair on your arm or face or elsewhere turns out to have yet another use that was previously unknown. Hair follicles, along with the folds and oil-producing glands in the skin, form a habitat for microorganisms that are vital to the skin’s ability to fight off harmful pathogens.
Nature News summarizes:
The folds, follicles and tiny oil-producing glands on the skin’s surface create a multitude of diverse habitats, each with its own community of microbes.1 Most of these “commensals” live harmlessly on the skin, and their presence is thought to stop pathogenic microbes from invading the skin’s habitats. But these benign residents are not just innocent bystanders — according to a paper published today in Science, skin-specific bacteria also influence the response from the host’s immune system to help fight off infection.2
Immunologist Yasmine Belkaid and her team at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, decided to investigate the immunological role of the skin’s resident microorganisms, known collectively as the skin microbiome. “For the first time, we’ve shown that the skin needs microbial signals for proper immune-cell function,” says study author Shruti Naik, a graduate student at the University of Pennsylvania, Philadelphia, who is based in Belkaid’s lab.
Mice raised in a sterile germ-free environment, thus without their normal complement of skin microbiota, were unable to mount an effective immunological response to attack by a particular pathogen — but the ability was restored after scientists introduced a normally friendly bacterium, Staphylococcus epidermidis.
We have a dear friend who’s quite germophobic and whose kids play with our kids. She’s always insisting that nobody may come into her house without a severe scrubbing of the hands, face, etc. I need to remember to bring this to her attention.
The finding, by the way, adds to earlier news that fine body hair is part of our defense system against parasites; see here: “Human Fine Body Hair and the Myth of Junk Body Parts,” ENV.