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Comment by illuminated | Hacker News Reader

And that characteristic is the ability to sweat. That's what made the human species "stand out from the crowd" and be able to outrun the prey.

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Meat eating really helps a lot too because we can shove a couple thousand calories in our face in basically no time at all compared to a herbivore that must graze and forage those calories. That alone lets us cover more ground week to week than a lot of species. When you top it off with an efficient high duty cycle transportation system (i.e. biped that can sweat) and from the perspective of a water buffalo it's like being chased by terminator.

Meat + fire = even more calories out of it.

fire made eating animal protein much more efficient. imagine the patience of eating raw deer off the bone - hours of chewing. With fire, it converted a monotonous task to something efficient

Cooking doesn't do anything for meat unless you cook low and slow. A quick cooked cut of meat is not easier or harder to chew.

Cooking made a big difference for vegetables because heat quickly breaks down some hard to digest fiber.

"In essence, cooking—including not only heat but also mechanical processes such as chopping and grinding—outsources some of the body’s work of digestion so that more energy is extracted from food and less expended in processing it. Cooking breaks down collagen, the connective tissue in meat, and softens the cell walls of plants to release their stores of starch and fat. The calories to fuel the bigger brains of successive species of hominids came at the expense of the energy-intensive tissue in the gut, which was shrinking at the same time—you can actually see how the barrel-shaped trunk of the apes morphed into the comparatively narrow-waisted Homo sapiens. Cooking freed up time, as well; the great apes spend four to seven hours a day just chewing, not an activity that prioritizes the intellect."

https://www.smithsonianmag.com/science-nature/why-fire-makes...

Is that also why humans aren't furry?

Correct, its a big benefit over the furry prey. Especially when chasing the animal in the hottest part of the day for hours, pre-modern people had quite a different life.

> pre-modern people had quite a different life

You know I've thought about this, and if you look at it a certain way, I think you can say life is no different.

We still wake up as a group. We still "hunt" except the payoff is money convertible to food. We still eat together. We still sleep together (just across from one another in houses).

It's neat to think about.

Also, the massive impact of having a complex enough brain to form complex and intricate social structures made it possible for humans to dominate the food chain.

Is that right? As a beardy guy, I find beard is cooler in Summer and warmer in Winter. I'd speculate that hair allows more heat transfer to sweat. Hair also send to keep a local air layer near the skin which helps Summer-cooling and Winter-heating.

How hot and/or humid is your summer?

I don't know really, UK, so not hottest, a bit humid on occasions.

Ok I think you might have issues with actual cooling needs up above 32/35+.

But, I don't think it matters much. It doesn't help, but it's a small surface area.

Keeping a "local air layer" near your skin is not going to help at all with summer cooling. You need constant sweat evaporation to cool off. I don't think a beard is going to have much effect either way, since it's small, and our cheeks and chins are not designed to radiate heat or even sweat much compared to most of the body.

Surely if the evaporation can cool the skin surface, then a local insulation layer would prevent ambient air from heating the skin. Just as a locally warmed layer prevents ambient air from cooling the skin during Winter.

It's certainly a hypothesis I've long held but never had chance to test.

Citations for support/contradiction welcome, thanks.

Unless it's above body temperature, the local ambient air isn't heating your skin up, and if it's that hot you need to sweat profusely to avoid hyperthermia.

I think the beard is cooler in summer because you lose so much moisture from exhaling, it would go to waste not evaporating from your beard. In the winter, it solidifies and adds an extra layer of insulation. But if we were pushing that much moisture out everywhere, we'd probably dehydrate much too quickly.

It probably also explains afro style hair - keeps the heat of the sun off at midday while the prey doesn't have that.

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