Scientific American / The Sciences
Article on hairlessness in Homo sapiens:
What is the latest theory (guesswork, “Just-So” story, idle speculation, pop-sci babble) of why humans lost their body hair? Why are we the only hairless primate?
Mark Pagel, head of the evolutionary biology group at the University of Reading in England and editor of The Encyclopedia of Evolution, fills us in: (edited for brevity)
We humans are conspicuous among the 5,000 or so mammal species in that we are effectively naked.
Scientists (those anonymous elves again!) have suggested three main explanations for why humans lack fur. All revolve around the idea that it may have been advantageous for our evolving lineage to have become less and less hairy during the six million years since we shared a common ancestor with our closest living relative, the chimpanzee. So – “the elves” agree that this was a gradual process that occurred over 6-8 m.y. ?
The aquatic-ape hypothesis suggests that six million to eight million years ago apelike ancestors of modern humans had a semiaquatic lifestyle based on foraging for food in shallow waters. Fur is not an effective insulator in water, and so the theory (which is it, “theory or hypothesis) asserts that we evolved to lose our fur, replacing it, as other aquatic mammals have, with relatively high levels of body fat. (How did we do this?)Paleontological evidence for an aquatic phase of human existence has proven elusive.
The second theory is that we lost our fur in order to control our body temperature when we adapted to life on the hot savannah. Our ape ancestors spent most of their time in cool forests (How do we know this when we haven’t established WHO these ancestors were?), but a furry, upright hominid walking around in the sun would have overheated. (How do we know this if we cannot describe the physiology of this unknown ancestor?) The body-cooling idea seems sensible, but even though lacking fur might have made it easier for us to lose heat during the day, we also would have lost more heat at night, when we needed to retain it. (Let me guess? We dug burrows and slept underground at night.)
How many furry mammal species live on the African Savanna today? 45.
Why, then, aren’t the other 44 furry-hairy mammals species extinct due to overheating?
Recently, a colleague and I suggested that ancestors to modern humans became naked as a means to reduce (this implies intention) the prevalence of external parasites that routinely infest fur. (Again, why aren’t the other 44 furry-hairy species dropping dead from external parasite infestations, and why aren’t the humans who live on the savanna today “free” from external parasites?)
A furry coat provides an attractive and safe haven for insects such as ticks, lice, biting flies and other “ectoparasites.” These creatures not only bring irritation and annoyance but carry viral, bacterial and protozoan-based diseases such as malaria, sleeping sickness, West Nile and Lyme disease, all of which can cause chronic medical problems and, in some cases, death. Humans, by virtue of being able to build fires, construct shelters and produce clothes, would have been able to lose their fur and thereby reduce the numbers of parasites they were carrying without suffering from the cold at night or in colder climates. (What happened to everyone “left behind” in Africa? So in this explanation, “humans” lost their hair-fur after corralling fire, inventing clothing, building shelters and moving to cold climates? And only then started shedding like crazy? These cultural advents indeed spread parasites and disease, which would point to the possibility that hairlessness may be a recent neotenic artifact.)
One enormous problem with these explanations involves the “flexible” neurotypical concept of time, in which adaptations appear out of nowhere, and just in the “nick of time” to “save” a species. Evolutionary changes are anticipated and “whipped up” by “a species”. How would this even be possible? Telepathy, ancient alien powers, will, forethought? MAGIC, of course; it’s the old “shape-shifter mythology” applied to evolution.
Don’t forget that we were informed in the intro that “the science elves” agree that “we” lost our fur-hair gradually over 6-8 m.y.a. even though “we” Homo sapiens have only been around for 100,000-200,00 years.
Naked mole rats are RODENTS.
Human lice infections, which are confined to the hairy areas of our bodies, seem to support the parasite hypothesis. Naked mole rats, animals that can be described as resembling “overcooked sausages with buck teeth,” also seem to support the theory: They live underground in large colonies, in which parasites would be readily transmitted. (So do oodles of furry animal species) But the combined warmth of their bodies and the confined underground space probably negate the problem of losing heat to cold air for these animals, allowing them also to become naked. (Aye, yai, yai!)
OMG! How unscientific can this discussion get?
Once hairlessness had evolved this way (what way?), it may have become subject to sexual selection—being a feature in one sex that appealed to another. (Once again, at some magic point in time ALL humans became hairless and sexual selection could begin! The reverse is more likely; sexual selection of less hairy individuals could lead to (relatively) hairless offspring) Smooth, clear skin may have become a signal of health, like a peacock’s tail, and could explain why women are naturally less hairy than men and why they put more effort into removing body hair.
Despite exposing us to head lice, humans probably retained head hair for protection from the sun and to provide warmth when the air is cold. Pubic hair may have been retained for its role in enhancing pheromones or the airborne odors of sexual attraction.
The nightmare of retroactive evolution:
A tiny and VERY RECENT number of modern social women zealously remove their vestigial body hair so that males will have sex with them, as if they wouldn’t otherwise! BTW – Removing pubic hair attracts pedophiles. These cultural practices are “the reason” that unknown ancestors became hairless over the last 6-8 m.y.