Why are humans one of the only mammals that don’t have fur all over their skin. What’s the advantage?
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It works well for hunting. Humans can run longer and farther than most animals, we’re just not as fast. We can chase our prey to the point of exhaustion because we evolved the ability to cool ourselves during physical exertion. Our bodies also breathe air more effectively than most animals while running to keep our muscles fuelled with oxygen.
The ancestors of modern humans did have fur, and technically modern day humans also have fur, or more specifically the remnants of fur. There’s many pros and cons to having fur and not having fur but broadly speaking over the majority of humans’ evolution the need to cool down became more important than the need to stay warm. Fur’s main purpose is as an insulator that helps keep the body warm, but it makes cooling down difficult. Humans evolved mainly in Africa where there’s a hot climate, and we’ve evolved to be able to run for sustained periods of time. Thus sweating won out as a cooling method. Fur is counterproductive to cooling down and also decreases the cooling efficiency of sweating, thus we’ve mostly done away with fur. That’s not to say however we don’t technically still have it. All humans still have hair all over their bodies, on some more prominent than others. It’s just not as logn and dense as it is in other animals like primates.
We are actually the only distance runners on the planet. We can’t out sprint prey on 2 legs, but we can tire out any 4 legged animal, we just have to keep jogging after them. Jogging means we are risking over heating so we need to sweat all over to cool off the body. This is where hairlessness comes in as well. It was so our ancestors could chase down herds of animals on foot
Humans evolved in the African Savannah. We developed a lot of traits to adapt to that sort of life, including a lack of fur and originally, dark skin.
Human beings evolved to stand upright and sweat – and sweating works better to control heat if tot have no fur.
The advantage this coveys is endurance. A human can walk further without resting than just about any other animal and primitive cultures engaged in exhaustion hunting – where they tracked an animal relentlessly until it collapsed of exhaustion. Walking upright is very efficient, energy wise, and sweating to cool down is very effective.
You can test this very easily. Take your dog for a very long walk and see which one of you has to stop first. You will win as long as you just keep briskly walking (assuming you are reasonably fit).
So here’s a small bit of trivia my old biology teacher told me a decade ago. You know when your hair stands on end? That’s a biological reaction triggered when you shiver to capture and retain more heat and a leftover from back when we used to have a lot more fur.
Sweating. Sweating is one of humanity’s greatest strengths. Other animals might be bigger, faster, and stronger. Humans are the best distance runners on earth, and the ability to sweat helps with that because we don’t overheat in the same way other animals do. We can literally walk animals on a hunt until they are too weak to move anymore and kill them with a stick.
Most mammals do have fur, but we are NOT the only ones who are not covered in fur.
In fact, we are covered in fur. We just call it hair. And we’re covered with it, normally. Other generally considered “hairless” species are elephants, walruses, whales, moles, many species of pig are commonly and naturally hairless. Even more hairless than we are.
There there are select species, or sub-species, which can be hairless, like Sphynx cats, some highly specialized sub-species of rats and mice… so, actually, our lack of hair isn’t in any way remarkable…
One thing to keep in mind when asking questions about our evolution is that things aren’t always advantageous. Sometimes they just aren’t disadvantageous and that’s good enough. If there’s a mutation and it doesn’t negatively affect the ability to survive and procreate, it might just stick around.
Not saying that applies in this case, but rather, suggesting it’s always good to challenge the assumption that something may be advantageous just because it exists.
Dogs and wolves can run around a hundred miles in a day and do it every day for weeks, in cold climates. In 95degrees and sunny, I can outrun a sled dog for 5 miles, to the point they’ll lay down and quit. Sweating is a huge advantage in warm climates for running distances, which was our primary hunting method.
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