With the summer heat in lots of parts of the country, you’ll have already turned in your air conditioner.
Also try plugging in a curling iron.
Researchers at Pennsylvania State University were intrigued by the undeniable fact that humans are unique amongst mammals with an almost hairless body but a hairy scalp.
“Humans evolved in equatorial Africa, where the sun shines overhead for many of the day, yr after yr,” Nina Jablonski, professor of anthropology at Penn State, said in a press release.
“We wanted to grasp how this influenced the evolution of our hair,” she added.
To seek out out if our hair evolved to assist early humans, scientists used a thermal mannequin – a temperature-controlled, electrified model of a human – to check how heat is transferred from the body to the atmosphere.
They then aimed the lamps at a mannequin’s head in 4 different hair states: no hair, straight hair, moderately curly hair, or heavily curly hair.
![two mannequins, one with curly hair, the other with straight hair](https://nypost.com/wp-content/uploads/sites/2/2023/06/NYPICHPDPICT000012324018.jpg?w=1024)
As expected, each of the three hair types limited solar radiation to the scalp, but tightly curled hair provided the very best protection against solar radiation and warmth.
And after wetting the scalp to simulate the perspiration effect, the tightly curled hair also minimized the necessity to perspire to remain cool, which might help conserve water and stop dehydration.
The authors of the study, published in Proceedings of the National Academy of Sciencesconsider that tightly curled hair helps to extend the space between the scalp and the highest of the hair.
They argue that the hair on our heads probably evolved as a option to reduce the quantity of warmth gained from solar radiation, thus keeping people cool without the body having to expend additional resources.
![infographic showing the results of a hair experiment](https://nypost.com/wp-content/uploads/sites/2/2023/06/NYPICHPDPICT000012324054.jpg?w=1024)
This likely gave early humans an evolutionary advantage by allowing our brains to grow.
“About 2 million years ago, we saw a Homo erectus that had the identical physical structure as us, but a smaller brain size,” said Tina Lasisi, who conducted the study as a part of her PhD dissertation at Penn State.
“And 1 million years ago, we mainly got to the trendy brain size by adding or taking. Something released a physical constraint that allowed our brains to grow.”
“We consider that scalp hair provides a passive mechanism to cut back the quantity of warmth gained from solar radiation that our sweat glands were unable to.”
Lasisi also believes that this research could have real-world applications.
“If you consider the military or different athletes training in several environments, our findings provide you with a moment to think and wonder: will this hairstyle make me overheat more easily? Should I style my hair optimally this fashion?” she said.