A Mite’s Choice
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Human faces are rife with microscopic mites that live, feed and reproduce on facial skin until their host dies.
Demodex mites primarily live on hair and feed on the oils produced in our pores. While generally harmless, they can cause an itchy, irritating condition called demodicosis in people with skin conditions or the immunocompromised.
The tiny bugs become part of an individual’s life during breastfeeding when mites leap from the mother’s nipple to the baby’s face – known as their primary way of spreading.
But the peculiar creature leads a very sheltered lifestyle in the pores, which protects it from the outside world and natural selection. Demodex also reproduces through inbreeding, which causes many mutations in their DNA.
Now, a research team found that their way of life could lead to their demise: After analyzing the genomes of more than 250 mites, they discovered that Demodex’s genomes were degraded and reshuffled as a result of decreased selection pressure.
The insect lost genes that coded for stress response, immune response and reproduction. The mutations also distorted its anatomy, resulting in a simplified body with the fewest number of cells of any known arthropod.
While some of these mutations are harmless, others could be fatal, the team warned.
They added that if the mites carrying these deadly mutations moved to a new host, their chance of survival remains dim – and they could eventually become extinct.