A new DNA research explains the strange mating patterns, bodily traits, and evolutionary prospects of mites that dwell in human hair follicles.
According to recent study, microscopic mites that live in human pores and spawn on our faces at night are evolving into such basic organisms as a result of their peculiar lives that they may soon become one with people. Bangor University and the University of Reading spearheaded the study, which was conducted in partnership with the Universities of Valencia, Vienna, and San Juan. The study’s findings were published in the journal Molecular Biology and Evolution.
The mites are handed down from mother to child and are carried by practically every human, with numbers increasing in adulthood as the pores expand. They are around 0.3mm long, live in hair follicles on the face and nipples, including the eyelashes, and feed on sebum produced naturally by cells in the pores. They become active at night, moving between follicles in search of a mate.
The first genome sequencing research of the D. folliculorum mite discovered that their solitary lifestyle and resultant inbreeding is leading them to shed unneeded genes and cells, causing them to shift from exterior parasites to interior symbionts.
Dr Alejandra Perotti, Associate Professor in Invertebrate Biology at the University of Reading and one of the study’s co-authors, stated: “Due to their adaptation to a protected life inside pores, these mites have a distinct arrangement of body component genes than other similar species. These genetic alterations have resulted in some odd physical characteristics and behaviours.”
Due to their isolated existence, with no exposure to external threats, no competition to infest hosts, and no encounters with other mites with different genes, genetic reduction has caused them to become extremely simple organisms with tiny legs powered by just three single cell muscles, according to an in-depth study of the Demodex folliculorum DNA.
They survive with the smallest protein repertoire yet observed in this and comparable species.
This gene decrease is also the cause of their nocturnal behaviour. The mites lack UV protection and have lost the gene that allows mammals to awaken when exposed to sunlight. They are also unable to synthesise melatonin, a substance that keeps tiny invertebrates active at night; nonetheless, they may fuel their all-night mating sessions with melatonin released by human skin around twilight.
The mites’ odd mating behaviours are also due to their unique gene arrangement. Their reproductive organs have shifted anteriorly, and males have a penis that protrudes upwards from the front of their body, requiring them to situate themselves beneath the female while mating and copulate while both cling on human hair.
One of their genes has inverted, resulting in a unique configuration of mouth-appendages that protrude to gather food. This helps them survive at an early age.
When mites are young, they have significantly more cells than when they are adults. This contradicts the previously held belief that parasitic animals lower cell numbers early in development. According to the experts, this is the first step toward mites becoming symbionts.
The lack of exposure to potential partners who may pass on new genes to their kids may have placed the mites on an evolutionary path that could lead to extinction. This has previously been observed in bacteria residing within cells, but never in a mammal.
Some studies hypothesised that because mites lack an anus, they must amass all of their faeces throughout their lives before discharging it when they die, causing skin irritation. However, the current study proved that they actually have anuses and have thus been wrongfully blamed for numerous skin problems.
Dr. Henk Braig of Bangor University and the National University of San Juan stated: “Mites have been accused for a variety of offences. Because of their lengthy relationship with humans, they may also have basic but crucial jobs, such as keeping the pores in our faces unblocked.”