Did humans wearing clothes prevent evolution (that would have let humans remain warm while naked?)

Factual Questions
21

Yes, natural selection - the essence of evolution, “selection” from random, rather than design.

Yes. The “Just So Story” is that humans started off coming down from the trees to scavenge the plains as the grasslands replaced the jungle. They evolved upright walking because the ones who could do that more easily could carry more food back to the safety of the trees. They began to scavenge the carcasses left behind by bigger predators. The extra protein was convenient for brain development, and took less time to chew. As human brains became bigger, they figured out how to use tools to kill their own game. Upright posture meant that they could run efficiently, thus they could harry big game to exhaustion. Learning to use fire (brains, again) meant they could break down meat with heat, so no need to select for raw meat consumption.

the key here is that humans could harass big animals to exhaustion because bipedal running was so efficient, and unlike their prey, they did not need to stop regularly to drink and graze. A horse or gazelle can easily outrun a human, but only for a few minutes before it stops to rest, the human catches up, and off the chase goes… until the gazelle is too exhausted.

Humans were selected for little hair and good sweat glands because that efficiently shed heat generated by running, in the tropical central African climate. They spread out across the tropics initially, the Mediterranean, the south coast of Asia, and into the Indonesian islands. No doubt they figured out to cever themselves with leaves or grass when it was a particularly frosty night, or just keep moving. But - the need to efficiently shed heat probably overbalanced the need to cover up.

By the time they moved into more chilly climates, they were already a top predator. IIRC, most sites in central Asia and Europe include a goodly assortment of bones from hunting. It would be surprising if, during that time, they had not figured out that the furry stuff on the outside of those animals was nice and warm. Plus, I recall reading about the plains in the middle east where they are littered with the remains of flint implements from up to 300,000 years ago - so they had the tools to skin animals as well as to chop liver. Presumably the process of making leather was a learning experience.

So yes, making clothes made selection for natural heat insulation much less significant. Environmental pressures are much less if you can modify your immediate environment. However… I have read that Inuit, for example, are somewhat suited for their situation - more subcutaneous fat as insulation. I don’t know about other ethnicities, but I am aware that I am not the only European that is not too far removed from a sheep (Scottish heritage?) in that I have a distinctive thick furry layer all over my body. Shaving my chest, for example, would be difficult because I wouldn’t know where to stop. I can grow a decent pelt on my face, but not the top of my head. So I suspect there is some residual evolutionary selection happening.

Oh, and you have to experience -40C (or -40F) to understand what real cold is. You can only do that without a jacket for a few minutes.

22

For a short trip, like fetching the newspaper, i might don a jacket below 20F, and would probably don a jacket below 10F.

I used to like to take a few steps in fresh snow, barefoot, though, just to feel the snow between my toes.

I’m much more tolerant of cold in the winter and early spring than in early fall, though.

23

Golden snub-nosed monkeys apparently “can withstand colder average temperatures better than any other non-human primate”. Lots of pics of them in the snow in GIS.

24

It was more likely the brains and bone marrow of the prey that was convenient for brain development, being awash with fatty acids (and much higher in energy than meat). And it took even less time to chew!

25

The main point being chunks of protein-rich (and fat-rich) animal flesh were much larger chunks of concentrated nutrients and calories than collecting small wild beans and roots and a lot less work to get. (I think people don’t always realize how much bigger we’ve made domesticated crops through selection). So scavenging and then hunting provided significantly more food value than simply collecting plants. Also by comparison, those mountain gorillas spend about 11 hours a day chewing the plants they collect, in order to make the food digestible. Humans chew for less time. The brain uses about 1/4 to 1/3 of the calories we consume, so evolution selecting for meat eaters, and for the brain which helped humans be smart hunters, was a sort of vicious cycle of specialization.

That brain power has made it possible for humans to survive in exotic climates without natural protection, by manufacturing their own. I suppose for example, water containers for desert travelers might fall in the same category as clothing for cold climates - we consequently did not evolve a separate species with the water-conserving adaptations like camels have…

26

Who’s to say that we didn’t evolve for our environments? Look at people in Africa, vs. Europe vs. Asia- different adaptations to the local climate.

For example, Europeans tend toward very pale skin, because where they lived, there was a lack of sunlight and vitamin D deficiencies were common enough that pale skin conferred a survival advantage.

Here’s an article that says that most non-African descended populations have certain genetic metabolic differences that date back to the Ice Age as adaptations to cold.

Ice Age Ancestry May Keep Body Warmer and Healthier - The New York Times (nytimes.com)

27

Thinking about this, I was pretty sure most primate species live in warm weather areas. Google says I’m right: “In truth, just four nations—Brazil, Madagascar, Indonesia, and the Democratic Republic of the Congo (DRC)—harbor 65 percent of all primate species.”

So, that would probably be the story for us.

28

I thought I remembered a pair of OG columns that pertains to this (although I could have also sworn there was a more detailed one about Inuit people’s adaptations that I cannot find ) -

And

Just always like to bring us back to our source when I can.

29

Well sickle cell disease is a clear example of a two edged trait - albeit one involving a single base pair. Clearly things do happen that potentially could get labelled as evolution within our species’ history. If the mutation didn’t have such a devastating effect on those unfortunate to get it from both parents, one wonders how it would be viewed? As an adaptation to environment it is pretty clear.

30

Years ago I took a Science Fiction Literature course in college, A guest lecturer stated he was pessimistic that as society became more advanced, we were doing the opposite of natural selection - we were permitting traits to spread that normally would cause those specimens to fail to survive or reproduce - from simple things like needing glasses, to other details like cancer susceptibility, tendency to miscarry or infertility, poor immune systems, etc.

Again, the question is whether some of these are attributable to heredity or environment.

31

Your guest lecturer was an idiot. “If we cure cancer, we won’t select for people who are immune to cancer!” Yeah, but who cares if we never evolve cancer immunity if we can cure it? Hell, if we’re using the big ol’ brains evolution gave us to cure cancer, how is that functionally different from evolving cancer immunity?

Not to mention, telling everyone in the audience with a disability that the species would be better off if they just died is a massive dick move, in and of itself.

32

Yes and no. Being able to cure cancer is great, until some catastrophe comes along and the solution is unavailable. In Frank’s Alas Babylon some of the first people to die after a nuclear war were the diabetics. Their little region is untouched, but supply chains broke down. Fortunately, our global supply chains are robust enough that we will never run out of medicines or essential goods.

Natural selection for “survival of the fittest” depends, always, on definitions of “fittest”. Poor eyesight will be a disadvantage if glasses are hard to come by - or if you use disposable contact lenses, have no backup glasses, and suddenly contact lenses are hard to come by. It wasn’t a suggestion that everyone in the lecture hall should drop dead, just a warning that we are going from becoming a global predator successful in all environments to a species like hummingbirds or pandas, highly dependent on a specialized set of surroundings. And this points to what the OP is asking - we make clothes, so we are unlikely to survive in some environments without clothes. We build shelters and use fire, so again, can survive in locations we were less likely to survive in without those; and can eat food that needs cooking to be easily digestible. So there is no “survival of the fittest” pressure to adapt to living naked outside in the cold without fire.

Another point to make to the OP is that mutations, beneficial or not, are useless if they don’t result in differential reproduction, more offspring who survive to themselves reproduce. (Another ancient SF novel to reference, Marching Morons .) Being smarter, richer, healthier, whatever is no advantage if you still have the standard 2.3 children everyone else does (or nowadays, 1.7 children). it seems that being a better off middle class couple, possibly due to genetic advantage, in fact results in less reproduction. But then, is social success more about genetics or environment? That’s a whole separate debate with no easy answer.

33

So, because diabetics wouldn’t survive a nuclear apocalypse, it’s better that they should die now?

It’s not just a stupid idea, it’s incredibly inhuman.

34

Nobody said they should die now… except you.

It was just a warning that life in general is tending toward a more fragile state. And in fact, in the days before Canadians discovered how to purify insulin 100 years ago, diabetics did die before passing the tendency on to children. Nowadays, diabetics (Type I) are one major catastrophe away from that. I’m not sure, for example, how reliable the pharmaceutical supplies are in, say, Mariupol or Aleppo. Or if the optometrists are still working there.

But the same applies anywhere - it’s far better to be healthy than to not be. And healthy depends on a lot of factors. At what point should you simply not have children because of genetics? There are people with diseases like Tay-Sachs and Huntington who go to some lengths to avoid passing it on. Bad eyesight, not so much.

35

If you’re presenting this as a “problem,” then you kind of are.

36

Considering the lecturer (and myself) were wearing glasses when I asked him “what about people who need glasses?” I suspect he did not mean it was a “time to die, Mister Deckard” situation.

37

I’d say it may have done the opposite, furthered evolution, meaning that evolution favored those who use their intelligence to move into new environments? And the early ones who did evolved into more intelligent humans who took it further? Since humans did spread out to colonize most of the land of the earth, I would think wearing clothing and building structures and taming fire in all places took considerable adaptive skills that simply were not needed in the ‘original place’.

38

Did Humans doing x prevent evolution of y?

Maybe. We killed off a lot of species that might have evolved past where they were, for better or worse. In other cases we promoted their survival but on our terms. We also influenced the breeding patterns for many species.

If there were a cultural group of humans that wanted to be naked all the time, we probably would have seen it by now. It’s doable in some climates.

39

I’d think this was absolutely the case. Every time that population pressure grew somewhere, some people would go elsewhere for better hunting or greener pastures or whatever, and then only the ones who were best equipped tended to survive and thrive. I don’t doubt that being smart was one of those things that helped people thrive and have more children than those who were able to merely survive. But it likely wasn’t the only thing. Clearly being able to pack on fat and burn it slow was an advantage. And other things were advantages in different places- pale skin, flatter facial features, more melanin, and so forth.

I’m not so convinced that civilization has “stopped evolution”. If I had to guess, it’s probably changed it, but it’s too early to tell just how.

40

I wonder if it all just needs to hold together until the advanced society cracks genetic engineering: the genetic need for glasses wouldn’t get passed on by someone who wore glasses, but would just, y’know, stop getting passed on — possibly thanks to a breakthrough from a guy who wears glasses.

And so on.