Posted on 04/25/2025 7:49:24 PM PDT by Red Badger
Have you ever wondered why you don't have thick hair covering your whole body like a dog, cat or gorilla does?
Humans aren't the only mammals with sparse hair. Elephants, rhinos and naked mole rats also have very little hair. It's true for some marine mammals, such as whales and dolphins, too.
Scientists think the earliest mammals, which lived at the time of the dinosaurs, were quite hairy.
But over hundreds of millions of years, a small handful of mammals, including humans, evolved to have less hair. What's the advantage of not growing your own fur coat?
I'm a biologist who studies the genes that control hairiness in mammals. Why humans and a small number of other mammals are relatively hairless is an interesting question. It all comes down to whether certain genes are turned on or off.
Hair benefits Hair and fur have many important jobs. They keep animals warm, protect their skin from the sun and injuries and help them blend into their surroundings.
They even assist animals in sensing their environment. Ever felt a tickle when something almost touches you? That's your hair helping you detect things nearby.
Humans do have hair all over their bodies, but it is generally sparser and finer than that of our hairier relatives. A notable exception is the hair on our heads, which likely serves to protect the scalp from the sun.
In human adults, the thicker hair that develops under the arms and between the legs likely reduces skin friction and aids in cooling by dispersing sweat.
So hair can be pretty beneficial. There must have been a strong evolutionary reason for people to lose so much of it.
Why humans lost their hair The story begins about 7 million years ago, when humans and chimpanzees took different evolutionary paths. Although scientists can't be sure why humans became less hairy, we have some strong theories that involve sweat.
Humans have far more sweat glands than chimps and other mammals do. Sweating keeps you cool.
As sweat evaporates from your skin, heat energy is carried away from your body. This cooling system was likely crucial for early human ancestors, who lived in the hot African savanna.
Why Aren't Humans as Hairy as Other Mammals? Here's The Science Humans have an internal cooling system. (zenzeta/Canva) Of course, there are plenty of mammals living in hot climates right now that are covered with fur. Early humans were able to hunt those kinds of animals by tiring them out over long chases in the heat – a strategy known as persistence hunting.
Humans didn't need to be faster than the animals they hunted. They just needed to keep going until their prey got too hot and tired to flee. Being able to sweat a lot, without a thick coat of hair, made this endurance possible.
Genes that control hairiness To better understand hairiness in mammals, my research team compared the genetic information of 62 different mammals, from humans to armadillos to dogs and squirrels. By lining up the DNA of all these different species, we were able to zero in on the genes linked to keeping or losing body hair.
Among the many discoveries we made, we learned humans still carry all the genes needed for a full coat of hair – they are just muted or switched off.
In the story of "Beauty and the Beast," the Beast is covered in thick fur, which might seem like pure fantasy. But in real life some rare conditions can cause people to grow a lot of hair all over their bodies.
This condition, called hypertrichosis, is very unusual and has been called "werewolf syndrome" because of how people who have it look.
A detailed painting of a man and a woman standing next to one another in historical looking clothes. The man's face is covered in hair, while the woman's is not.
Petrus Gonsalvus and his wife, Catherine, painted by Joris Hoefnagel, circa 1575. (National Gallery of Art) In the 1500s, a Spanish man named Petrus Gonsalvus was born with hypertrichosis. As a child he was sent in an iron cage like an animal to Henry II of France as a gift.
It wasn't long before the king realized Petrus was like any other person and could be educated. In time, he married a lady, forming the inspiration for the "Beauty and the Beast" story.
While you will probably never meet someone with this rare trait, it shows how genes can lead to unique and surprising changes in hair growth.
Maria Chikina, Assistant Professor of Computational and Systems Biology, University of Pittsburgh
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Right… slowly, gradually over an insanely long period of time for some reason we became hairless because that makes total sense for any mammal to go without a protective layer… 🙄
It’s so blatantly clear how this stuff is such utter garbage when you really think about it. It’s hate for our Creator is all it is.
Thanks Red Badger. We're all descended from one prehistoric ancestor, Pontius Depilatus.
Because we’re not related to animals. We are separate creatures, made in the image of God.
in before the “i’m not saying it was aliens” guy
So obviously the hairless human did not “evolve” less hair. The gene is and was already there...it is just turned off.
The researcher should find out if sedentary people who don’t hunt for food by tiring out prey...get the hair gene turned back on. Lots of people are sedentary nowadays.
I wouldn't call it an "ability." More like a "susceptibility" or "vulnerability."
Regards,
The armadillos object
When the hairless aliens mated with the apes, the result was a creature that is almost hairless. Everybody knows that.
Less hair meant less fleas and lice. Hunters wouldn’t scratch and fidget when stalking dinner. Chicks dig dudes that bring dinner.
hormones
Unlike this flake, Elaine Morgan correctly answered this question in her book The Decent Of Woman.
https://en.wikipedia.org/wiki/The_Descent_of_Woman
Humans have acquired several drastic changes which separate us from our simian ancestors while others of their progeny changed very little. Of necessity, these changes would need to 1) all be related to a single niche we had to fill, and 2) all be related to the survival of hominid ancestor infants.
This flake’s explanation fills neither requirement.
Wow. The Morgan book link I posted is just wrong. Searching for a replacement.....
Elaine Morgan’s book The Decent Of Woman cites several human evolutionary changes which which were all adaptations to a marine environment.
1. Upright gait.
2. No fur.
3. Unique downward-turned nostrils.
4. Continuously growing head hair in women.
5. Infant survivability in water.
6. Infant finger grip.
7. Female subcutaneous fat layer.
8. Extra-muscular breasts.
While men were off chasing small animals surviving women were evading predators by running into the surf with their infants.
2. No fur.
Well most of it arm pits and groin to reduce friction hair on head for protection?.
It’s why you smell hair when fast walkers pass you.
Most women’s hair thins after infant-rearing age. LOTS of men lose most of their hair. Why wouldn’t continuously-growing hair in these people matter to species survival?
I’ll give you one point though. On men, where is the most vulnerable point to physical attack, and why do men have continuously-growing beards throughout our lives?
Because we have Gillette?
Why wouldn’t continuously-growing hair in these people matter to species survival?
Ageing process even animals have some traits of it.
why do men have continuously-growing beards throughout our lives?
Not Native Americans it’s in the breeding process.
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