Ahhhhhhhhh! Paleo-porn
Speak for yourself, bub. You obviously haven’t seen some of the guys I’ve seen without shirts on. (myself included)
Seems to me though, that chest/back hair on men is some kind of secondary sex characteristic like deep voices, beards, etc…
If they were a survival mechanism, women would be pretty hairy too, but they’re not nearly so hairy as men.
Is this true? IIRC, the hair is just finer and softer on women, but is the same amount and areas as men.
Hairlessness (which is really less hairiness), might date to the time when humans began to stand upright and became long distance runners. A hairless body might have been an adaptation to the changing body temperature stability conditions. This could also relate to why humans have pubic hair. Hair is less effective at blocking the sun in an upright posture. Or not. That’s the trouble with evolution. We occasionally find the when, we rarely know the why. There’s a lot of variation in hairiness, from people with little or only very fine body hair, or someone like my friend who had a think coat of hair everywhere on his body below his ears. That much variation makes it difficult to deduce how hairy anybody was 100,000 years ago.
Right now my main concern is maintaining some hair at the top of my forehead as my scalp evolves into a hairless state.
In that sense, humans in general are just as “hairy” as chimps. We have similar numbers of hair follicles on the body, it’s just that human body hair is much shorter and finer.
There are certainly people today who’re as hair as the common “hairier” depictions of cro-magnon and older relatives, but it’s my impression that most genetic sub-groups are pretty hairless. Most of those are in Africa, where I suppose hairlessness arose and remains an advantage, but if we lost most our hair 1.2 million years ago, did we leave Africa hairless and then to some extent “regress”?
I’ve heard this maverick theory that in response to cold ice-age European climates, the Neandertals re-evolved thick coats of hair and may have looked more like Bigfoot. Apparently archeological evidence of clothing (bone sewing needles) only date from Cro-Magnon times.
Or Ringo Starr.
How is hairiness passed on genetically? Does it follow maternal lines, paternal lines? Is there a sexual selection component to it?
Well, I suppose I should have defined “hairier,” but what I meant is that women don’t have the longer, darker, thicker hairs that men do ,and that women’s hair doesn’t appear to me, to be particularly useful for insulation. Ergo, the very visually obvious male body hair is a secondary sex characteristic, not an environmental adaptation.
The fact that women never have facial hair and (usually) little body hair suggests that temperature isn’t a strong selection pressure for such. Or that it’s use as a sexual-recognition feature overrides it. I can imagine, though, that in climates where people wore bulky clothing, men would get more chicks if they looked more masculine in the most visible part of their bodies - their faces.
Neanderthals (and even earlier humans) had bone scrapers that were probably used to prepare hides for clothing (although not the needles used to make tailored clothes). Genetic divergence between human body lice and head lice suggests that clothing may have first been used about 170,000 years ago.
Europeans (or at least some of them) are among the hairiest human populations, while many Asian and American Indian populations are comparatively hairless. It would be difficult to draw any conclusions about the condition of the modern humans who first left Africa since populations outside of Africa are so variable in this character.
Given that northern Asians and Eskimos are among the least hairy populations, it is unlikely that the degree of hairiness in modern human populations is related to selection for insulation. We’ve had clothes long enough so that body hair is rather irrelevant for thermoinsulation.
Maybe, but I suspect that a bristling beard and mustache are more related to intimidating other male rivals rather than attracting females directly.
Actually, just the opposite.
The first humans were hairless. Ditto for the first Chimps.
In evolution, the first creature necessarily is hairless, bc the development of hair is a reaction or a response to the environment. Hair, fur, feathers, evolved later, probably evolved when the creatures migrated to cooler climates. The creatures with hair, feathers , fur, more hair, more feathers, more fur survived better at some point in time.
Ditto for the very first cell/spark of life to be created on Earth, the first bird, the first frog, the first puppy, etc were all t also hairless in the earliest stages of evolution.
Actually, women do have hair on their faces, it is usually very light, very sparse, very short, very thin, but it is there.
In fact, even very marginal improvements that translate into reproductive success will tend to propagate quickly through the population due to accumulation, in the same way that compound interest can build up capital. Random mutations that don’t have any direct impact upon reproductive fitness or success can still accumulate in a non-linear fashion depending on what other genotypes they may be linked to.
Stranger
This makes so little sense in the context of the discussion I don’t think there’s much point in addressing it.
Nope; it’s just that caves are better than preserving many things than an open plain or forest is, and were convenient shelters when available.
And in the case of facial hair, though a beard might be nice on a brisk day, it’s actually a bit of a liability in actual severe cold conditions because it traps moisture and stops you from warming your face with your hands. A lot of the European arctic explorers (who would normally have elaborate Victorian facial hair) learned that you had to “go native” in the arctic and stay clean shaved to avoid frostbite.
Obviously you never met my Aunt! :eek:
in afghanistan, US soldiers discovered that shaving everyday is near-fatal. the reason the taliban required beards for males is not due to some cockamamey religious rule but rather out of concern. beards, mustaches, and mutton chop sideburns protect you from the fierce sun. GIs learned quickly to grow long beards while in 'stan.