To sum up feebly what others have said: there doesn’t need to be an advantage to a trait like long head hair. There just needs to be no sizable detriment to that trait leading to reproductive fitness. And if it were found to be attractive/showy/sexy…well, there ya go. So much the better.
I imagine that pubic hair and other as secondary sex characteristics were/are a useful signal to reproductive readiness, and have endured for that reason. They also serve as a conduit for pheromones from the apocrine glands, FWIW.
Beards let others tell who is a mature male at a distance. That’s a visual distinction lots of species have, so it clearly commonly has some evolutionary benefit.
This is actually a pretty good indication that there is *no *evolutionary benefit to long hair. If the evolutionary pressure was so high that no women would mate with bald men, then baldness would eventually no longer happen. Those genes wouldn’t be passed on. But we’re not disgusted by bald heads or by hair on heads. We each have our personal preferences, of course, but as a whole species, we don’t revile the bald.
There are lots of traits which “just happen”. There is no reason for them that we can discern. There’s no advantage or disadvantage. Genes mutate, and variances from the norm occur and are passed down to offspring. If the mutation is very beneficial - if the mutation gets the mutant laid more often with fertile offspring compared to the “normal” individual - then over time, it may become the new normal. If it’s not helping the individual get laid any more than the “normal” individual, but neither is it preventing the individual from getting laid and having fertile offspring, then over time it will simply be one variation within the norm. If it prevents an individual from getting laid and/or from having fertile offspring, the mutation will die with that individual.
There’s no benefit to having hair on the middle section of your finger, but it’s a genetically linked trait. (I bet you half the readers just looked at their fingers…it’s so inconsequential that most people don’t even know whether or not they have hair on the middle section of their fingers until you mention it.) Somewhere along the line, someone’s DNA mutated and that person was born with a gene that allowed hair to grow on the middle section of the finger. It didn’t help them get laid, but it didn’t prevent them from getting laid, either. It was neither a benefit nor a drawback. So that person had some babies, but not more than anyone else, and those babies had babies, some of whom had the hairy middle section gene, and those babies had babies, but neither remarkably more or less than anyone else…and now hairy middle sections are just one variation on body hair.
It does not have to be an advantage to be passed down. It just has to not be a disadvantage.
It may have to be an advantage to cause a dramatic shift in the phenotype of the species. But most mutations are not that. Most mutations are tiny and inconsequential.
Is having head hair the kind of dramatic shift in phenotype that would indicate an evolutionary pressure caused it? Eh…maybe. We could make up many “just-so” stories proposing evolutionary advantages to long hair. But the real answer is that it’s not clear whether or not long hair is actually advantageous at all. There are a whole lot of people whose natural hair is not long at all, it’s very curly and clings tight to the head unless you futz with it a lot and do unnatural things to it. It’s likely that long hair is just one of the many “normal” variations of human phenotype - neither grotesque enough that no one will sleep with you nor stunning enough to attract significantly more mating opportunities.
actually hair protect you from bacteria… ask a bear ;).
protection against scratches
protection against sunburns (nature’s hat)
heat, sweat evaporation control… if you live in a hot climate, you might have seen, during the hot summer days, some guys “wearing” a towel over their shoulders and the back of their neck… they don’t have long hair
reproduction… a sign of youth and good health
protection against insects… the vast majority of them can’t live in a hairy environment
men live rougher lives than women… they need more protection… in general they have more hair
a sign of coming to age, for reproduction
social status (eg “wise old man with long beard”)
a sign of age… white hair…
intimidation… they look more “manly”… think twice before you mess with them
economical protection… hair is cheaper than a constant flow of some lubricant fluid that would protect your body parts from rubbing against each other
pubic hair… protections against all things mentioned already (insects, sunburns, scratches, etc)
Long head hair, most likely, has to do, mainly, with how humans cool their bodies.
How they got “upright”… starting covering longer distances.
Most of the heat leaves the body from the shoulders, the neck and the head.
They real question ought to be “Why humans have so little hair compared so the other mammals?”
But… the most crucial question ought to be “Why some women have mustages?” yahhh :eek:
That doesn’t explain why ALL humans have long head hair. And remember baldness DOESNT prevent people from getting laid. Many tribes shave their hair off… So if baldness doesn’t prevent people from getting laid, why is baldness never passed on? (I mean for children - children start off with long head hair - unlike apes who don’t have that)
Being super “hot” and sexually aggressive would cause them to get laid more often… but as long as some others still get laid then the “hot” genes won’t completely dominate. BTW the amount of body hair varies… from hairy backs to relatively hairless people… but long head hair is still universal. Male pattern baldness is fairly common but they still have long head hair in some places.
It is universal so there must be a reason for that. If it wasn’t universal then it wouldn’t need to be advantageous.
Can you show me an example of someone who’s never really cut their hair yet their hair in its normal state is short? I’m sure that their hair would still be longer than an ape’s so their head hair is still relatively long compared to our ancestors’.
There is a downside in growing long hair, in that you need to expend the energy to grow it. On the other hand, if you are able to expend the energy to grow long hair, it may show that you’re healthy enough to do so, which wouild be a sign to members of the opposite sex that you’re worthy of mating with. You’re showing off that you can afford to spend the energy to grow healthy, long hair.
In modern society, it’s not that hard to be healthy enough to grow long hair, so it doesn’t really show you anything anymore. It might just be entrenched in our genes, but it needn’t have always been so. When we as a species were much much fewer in number, and barely surviving, it could have served a similar role as the peacock’s feathers.
You said its fairly long if you “futz with it a lot and do unnatural things to it”… also if it was tight and still long then you’d have a ridiculously huge Afro.
It is still longer than apes - so still everyone’s hair got longer.
The brain can overheat pretty easily and malfunction-- the big danger from a high fever is brain damage. That’s why we don’t accumulate fat under our scalp in proportion to the fat on the rest of our bodies, but we still need some cold protection on our heads, and hair is a good compromise, especially since it can get sweat-soaked, and give us heat protection, and also keeps our scalps from getting sunburned.
As for bald men not getting laid-- most men who are destined to become very bald do not become so until they are middle-aged, and that was beyond the life expectancy of most paleolithic people. It’s still beyond the age that most men father children. Men who are bald in their forties may have fathered babies when they were 27, and had all their hair still.
Not that I personally consider baldness a deal-breaker (although bad toups and combovers are); I’m just saying that most men pass on bald genes before they actually are bald.
There’s more than one type of baldness, and it’s not controlled by a single gene. For one thing, the amount of testosterone a man produces influences baldness, and that’s a Y-chromosome trait.
A psychiatrist was moved to study that back in the 1950s, when he observed that one of two identical twins had become bald, and one had not. The one that had not was schizophrenic, and had been castrated in order to control his aggressive behavior (this was before Haldol, and most sedatives).
I can tell you for a fact, as well, that my mother’s father and brother are both bald, but her maternal grandfather and my brother are not. Also, one of my mother’s brother’s son’s is losing his hair; I don’t know whether his maternal grandfather was bald, but his mother’s brother isn’t, and he is in his 70s, so that’s pretty remarkable. My father had hair right up until the end of his life as well, and he was on chemo, with his hair just getting a little thin all over. Whatever baldness is in my mother’s family doesn’t seem to be X-linked.
In other animals this kind of hunting is called cursorial hunting, utilized by wolves, hyaenas, and Cape Hunting Dogs. Not sure about hyaenas but wolves anyway do not sweat at all except through the pads of their feet. I grant the less hair part of the human cooling system.
Wikipedia tells me the other cursorial hunters on this planet are the lungless spiders of Africa. Which I am betting not everyone on this board knew already.
LOL. Yeah, I probably could have worded that better! But I think there’s a huge everywhere-but-the-largest-continent-in-the-world bias in the question itself. I work with a lot of African American people, and I hear a lot of hair woes. I hear a lot about how fragile hair of African origin is, and how slowly it grows, and how easily it breaks and thins. Black women spend hours and hours (literally, they tell me 6 hours is not an unusual amount of time) at the hairdresser putting noxious chemicals in their hair, putting false hair in their hair and finally giving up and buying wigs to put over their hair, all in an attempt to make their hair something it naturally isn’t.
Can some black people grow their hair long? Yep. But they’re not the majority, and they’re often “mixed race,” I’m told.
Last year, I cut my (white girl) hair from the middle of my back to just below my chin, and people actually cried for me. I couldn’t figure it out, until I realized they thought it was going to take me 10 years or more to grow it back out. Here we are a year later, and my hair is back down to my bra strap. They’re amazed at how fast my hair grows, when it’s really not any faster than average for my genetic background. But my hair is stronger and straighter, so it only grows in one direction, while theirs has to grow around and around and around before it gets any length to it.
And we’re all aware that humans didn’t evolve from gorillas, right? Please tell me we’re aware of that… I think it’s entirely possible to look at this handsome fella and recognize that we probably share a common ancestor with hair something like his. The better question is probably why the mutation that made the rest of our hair that isn’t on our head so short and sparse was advantageous. There are plenty of hypotheses about that. It’s unlikely that we were bald on the head and then mutated to grow long hair there.
Apes have dark skin, and don’t need sun protection on the top of their heads.
People in Northern and Central Europe had an evolutionary advantage if they got the mutation for light skin, because they could absorb a lot more sunlight and make a lot more vitamin D, even when most of their skin was covered up to protect them from the cold, but when the warmer seasons came along, having their heads covered with hair so they didn’t burn was also an advantage.
ETA: That orangutan looks like a Hebrew school teacher I had once.
