When birds live on an island without predators, their wings shrink, and they lose the power to fly.
This is because flying costs a lot of energy, so the bird has to eat more food.
At the same time, hunting and foraging for food are almost constant and exhausting. Every day is a delicate balancing act.
But everything changes on that peaceful island, where nothing tries to kill them: life is so comfortable and safe that birds don’t need an escape plan. And so, in an evolutionary shift, their wings shrink.
The secret life of mites has been revealed. Image: University of Reading
Something similar has happened with the microscopic mites (Demodex folliculorum) that live in our pores and mate happily on our faces at night.
Where the mites were once parasites, they have become much simpler organisms — and have developed a more symbiotic relationship with humans.
A fascinating new study suggests they are “becoming one” with humans.
Think of them as live-in help on a pretty good wicket.
The mites come in when we are born.
Our early life in the womb is the only time in our lives that we are mite free.
We pick them up when we are born and wear them for the rest of our lives.
Each mite is about 0.3 mm long. There are more than five of them in every square inch of your face and nipples, which can be found in and around your lashes.
Newly discovered: the anus of the mite. Image: University of Reading
These mites prefer the hair follicles where they feed on the sebum – the oily, waxy substance produced by your body’s sebaceous glands.
Sebum mixes with fat molecules (lipids) and protects the skin.
Excess sebum leads to clogged pores and blackheads, and subsequent irritation.
Mites are often blamed for skin irritation, but abundant sebum suggests you may need more than less.
If you get a tingling sensation on your face at night, in the dark, it probably isn’t mites moving between the follicles to mate. Actually, that’s what they’re planning, but you’re unlikely to feel them.
New study: more than you’d like to know
A research team led by the University of Bangor and the University of Reading, in collaboration with the University of Valencia, the University of Vienna, and the National University of San Juan, has completed the first genome sequencing study of the D. folliculorum mite.
The researchers found that “their isolated existence and resulting inbreeding causes them to reject unnecessary genes and cells and to move from external parasites to internal symbionts”.
Dr. Pores. Alejandra Perotti, associate professor of invertebrate biology at the University of Reading who co-led the study, said: “We found that these mites have a different arrangement of body part genes than other comparable species as they adapt to sheltered life. PThese changes in their DNA have led to some unusual body characteristics and behaviors.”
Little vampires confined to the night
The in-depth study of the Demodex folliculorum DNA revealed that living in isolation does not expose the mites to external threats.
They have no competition for food (all that tasty tallow) – and they don’t come across other mites with different genes to breed with.
This means their genetic pool has shrunk as a species — but they’ve lost many genes, making them “extremely simple organisms with tiny legs powered by just three single-celled muscles.”
It is related to those island birds that lose their wings.
A consequence of their evolved simplicity is that these mites “survive with the minimal repertoire of proteins – the lowest number ever seen in this and related species”.
As a result, they have fewer resources to fight the outside world.
They have been forced to be active at night inpartlyecause their gene reduction has taken away their built-in UV protection nd because they have also lost the gene “which causes animals to wake up in daylight”.
This a strange example of people helping
Humans produce melatonin, which makes sleep.
In small invertebrates, melatonin keeps them active at night.
But facial mites can no longer produce melatonin, which prevents them from moving around during the day and night.
So how come they stay up all night making a cry in our pores? They can access the melatonin we secrete through our skin when the sun goes down.
Downstairs has moved up.
In general, their mating habits are a bit strange, as is their approach to marriage.
The reproductive organs of the mites have moved toward the head of their bodies, and males “have a penis that extends upward from the front of their bodies.”
The scientists say this means positioning themselves below the female during mating “and copulate while both clinging to the human hair.”
The mite’s penis is where its nose should be. Image: University of Reading
The mites have developed extra mouth appendages to collect food, which aids their survival at a young age.
Although there are all kinds of openings for food to enter, some researchers assumed that mites do not have an anus “and therefore must accumulate all their excrement throughout their lives before releasing it when they die, causing skin inflammation”.
This alleged low point is not true. They have an anus that does what the anus does.
And they probably aren’t responsible for as many skin infections as once thought.
Dr. Henk Braig, the co-lead author of the University of Bangor and the National University of San Juan, said: “Mites are blamed for many things. Their long association with humans could indicate they may play a simple but important beneficial role. , for example, by keeping the pores in our face loose.”
the end of days
The lack of exposure to off-species partners means that the gene pool of mites shows dangerously low diversity.
The researchers believe this has set them on course “for an evolutionary dead end and possible extinction”.
In other words, they could become the Dodo of the mite world.