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Author: u/Wagamaga
URL: https://www.psu.edu/news/research/story/life-air-conditioning-curly-hair-kept-early-humans-cool/

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I love that the conclusion here is that big brains started with big hair.

So as humans moved north their hair became less curly? I wonder what evolutionary benefits straight hair has in colder climates. It seems like curly hair would still provide better insulation against cold by trapping more body heat.

TIL the sun prevents brain growth

Curly hair does more than simply look good — it may explain how early humans stayed cool while conserving water, according to researchers who studied the role human hair textures play in regulating body temperature. The findings can shed light on an evolutionary adaptation that enabled the human brain to grow to modern-day sizes.

“Humans evolved in equatorial Africa, where the sun is overhead for much of the day, year in and year out,” said Nina Jablonski, Evan Pugh University Professor of Anthropology at Penn State. “Here the scalp and top of the head receive far more constant levels of intense solar radiation as heat. We wanted to understand how that affected the evolution of our hair. We found that tightly curled hair allowed humans to stay cool and actually conserve water.”

The researchers used a thermal manikin — a human-shaped model that uses electric power to simulate body heat and allows scientists to study heat transfer between human skin and the environment — and human-hair wigs to examine how diverse hair textures affect heat gain from solar radiation. The scientists programmed the manikin to maintain a constant surface temperature of 95 degrees Fahrenheit (35 degrees Celsius), similar to the average surface temperature of skin, and set it in a climate-controlled wind tunnel

The team took base measurements of body heat loss by monitoring the amount of electricity required by the manikin to maintain a constant temperature. Then they shined lamps on the manikin’s head to mimic solar radiation under four scalp hair conditions — none, straight, moderately curled and tightly curled.

https://www.pnas.org/doi/10.1073/pnas.2301760120

I'm from Yorkshire, why the F do I need curly hair? It's freezing here!

All they did is shine a heat lamp on a manikin with different wigs. I am struggling to see how this proves brain size is the result

Cooling occurs largely from circulating blood and your through your forehead, neither give a damn about how curly your hair is.

The inactivation of (IIRC) the myosin light chain 3 gene also played a big role since it resulted in a reduction in the size of the muscles between the jaw and sagittal crest, reducing a restricting force on our skulls which allowed them to grow.

As someone with 3B/C, I find the opposite to be true, very insulating in the winter, basically up all summer

Could this also explain the reason for the growth of pubic hair? To keep the reproductive organs relatively cool in hot environments when pre-humans wore no or very little clothing.

Sooo….
Humanity would have been extinct if I were one of the first to live …. Since I am bald.

Would balding be a negative then? Surprised it persisted.

Uncle Paul (maybe it was Eric) once told me that Afros keep your head cool in the summer and warm on the winter. After learning about insulation it makes sense. It not the layers that moderate temperature, it’s the air in between the layers. The layers are barriers. Plastic stop flow so it’s good for windbreakers and sweating. Goose downs are a perfect example. The plastic outside stops the outside air from affecting the temperature of the down. The cotton inside allows for your body, then, to warm the down. The down staying warm eventually reduces the necessary heat for your body to generate in order to be warm. Anyway, i just smoked.

thought our brains grew big because our jaw muscles atrophied from quads, into, well, today’s jaw

So what about people without curly hair?

I googled Dr. Tina and I see an immediate conflict of interest. But all the racially charged potential insinuations aside, I always wondered about the hair. Why out of all the primates do we have so much, even orangutans can't grow a poney tail or afro. It makes so much sense in hindsight; big brain ape has more hair on brain area. I mean, it could have been extra protection from injury, but the heat thing makes sense given how it disappeared once humans migrated to colder climates.

Curly hair means big brains??

ha.

so all those flat hairs who made fun of my curly hair in school are less evolved than i am.

i knew it.

One of the biggest reasons why I don’t leave my hair curly is because of how uncomfortable it is in the heat. It is 1000 times easier to deal with if your hair is straight, even if it’s not stick straight due to the humidity, than it is to deal with curly hair that just reminds you of how heavy it is all the time

Ok but ban the broccoli cut

This is already known I thought?

i wonder if it still has any residue/effect left in modern times. like people with very curly hair being slightly more intelligent? that would be cool ngl

Cool. I never liked mine though

And... was straight hair just something people found more attractive later on, like blue eyes?

Not sure what's ground breaking here. It's pretty simple physics. It'd need to balance blocked sun with enough airflow to allow sweat to evaporate, which also explains why straight hair evolved outside of Africa. It holds moisture, thus reducing airflow, negating cooling effects of sweat. Basics of "survival of best fitment."

Ah! The beauty of this theory! It can explain everything and it's opposite, it doesn't explain anything at all.

For anyone curious, this is also why pubic hair is curly.

On a structural level, pubic hair, and African hair are indistinguishable.

ah! I curly hair! me big brain!

Early man had a fro, film at 11. I thought we knew this.

So what about the elongated skulls?

"new" ? Wasn't this long known and understood?

So the 70s was important for our evolution in the world is what these folks say?

“My hair’s *electric* man, it picks up all the vibes.” -Jimi Hendrix

Also it would prevent the problem of skin cancers along the partline in the hair. Your scalp/top of your head is the body area exposed to the most sun.

So explain why pubic hairs are curly ? Clearly not to keep by balls cool.

Ive never had a harder time regulating my temp than when I bic’d my head.
Curly, perhaps dry hair holds moisture in combination with a lot of surface area, similar to the straw in a swamp cooler.

Loll that’s all it took. Curly hair.

The hair of African descent follows the pattern of Earth as it rotates around the nearest star, our Sun. Actually it leaps like a spring but your not supposed to know this……. Research the Lost 11 days of September 1752 and how the Earth moves. Comparing the correct time measurements.

Ok, nature. Please, explain balding now

I have fine straight hair and my ancestors come from northern England and Scotland where it’s misty and rainy, so I guess it would be an advantage to hair that dried quickly

Reminds me of the monologue by Redd Foxx with the punchline "Lord, why the hell am i in Cleveland?"

This is not new. The brainiacs have already mentioned this before.