What could be more massively useful than fur? The only mammals other than us who don't seem to have it are cetaceans. Even seals and beavers and other aquatic mammals maintain a nice thick coat. What happened to ours? What possible adaptive advantage could we have had to lose it? Or is it not adaptive at all and just a weird founder effect sort of thing?
Here are some theories I can think of. None of them seems very strong to me.
1) Heat loss. Humans evolved in quite warm climates.
2) Aqua man. At some point in human evolution our ancestors gained adaptations for aquatic life.
3) Cleanliness. Carrion eaters often have baldness as an adaptation that decreases bacteria, rot, filth. Example is a vulture's bald head.
4) It's Sexier. This is what Desmond Morris thinks so I include it though I think he's sort of .
5) No reason at all. Perhaps a side effect of our general neoteny compared to our closest relatives. Or a contingent fact of history due to founder effect or other random occurance.
6) It's an adaptation connected to wearing clothes, somehow. None of the other mammals wear clothes.
7) Sexual selection. It's prettier.
8) To allow more sunlight onto our skins for the purpose of making Vitamin D.
9) To allow us to more easily rid ourselves of ticks, lice, and fleas, and to provide a less hospital home for them.
Can anyone advance a better hypothesis? What observations support or counter each possible explanation?
[ August 06, 2003, 11:43 AM: Message edited by: ak ]
Posted by ak (Member # 90) on :
We've had at least 20,000 years living (on land) in cold climates, (some populations of us at least) so I would think with the huge amount of variation in the hairiness of people that if fur were adaptive for us, we could have easily gotten it back. This tends to undermine hypotheses 1, 2, and 5.
[ August 06, 2003, 04:36 AM: Message edited by: ak ]
Posted by ak (Member # 90) on :
Apes also evolved in warm climates and they are fully furred, ditto every other warm-climate mammal I can think of. This tends to undermine hypothesis 1.
Posted by ak (Member # 90) on :
Our heads and faces are the least bald part of us, particularly males. This would tend to undermine hypothesis 3.
Posted by ak (Member # 90) on :
None of the other mammals seem to have any problems breeding in great numbers despite being fully furred. Far faster than us, even. This undermines 4.
Posted by ak (Member # 90) on :
It's true that wearing clothes if you have fur is quite uncomfortable and unpleasant, but, hey, if you had fur you wouldn't NEED clothes, would you? This seems circular. I don't care for hypothesis 6 because of that.
Posted by ak (Member # 90) on :
Hypothesis 7 gets pretty well blown out of the water when you realize a few things.
a. The tendency to be attracted to certain features in a mate is a heritable trait which is subject to natural selection. The trait of thinking non-adaptive traits are attractive will tend to be weeded out of any population. There are plenty of women who think hairy men are sexy, for instance, and if hairiness were an adaptive trait, their offspring would tend to prevail.
b. All the other traits which evolutionary biologists characterize as being due to sexual selection are expressed only in males. Our relative baldness compared to other mammals is true of both sexes.
[ August 06, 2003, 04:59 AM: Message edited by: ak ]
Posted by Maccabeus (Member # 3051) on :
Long ago I read a Science Digest article proposing #2, that humans were aquatic apes. I found it amusing, but it made some useful points. Humans can swim; apes can't. No ape has even the tiny amount of "web" between the fingers that humans have. Apes do not (I think) show the "diving reflex" that slows heartbeat in cold water. There may have been some other points, but it's been too long.
Posted by ak (Member # 90) on :
We are the only ape with nostrils that open downward. We are the only ape with the ability to flare our nostrils, which could perhaps be a remnant of an earlier ability to close them completely. The upright stance could be a side effect of a rotation backwards of the lower legs for swimming purposes.
[ August 06, 2003, 05:03 AM: Message edited by: ak ]
Posted by Ralphie (Member # 1565) on :
I think someone made off with Anne Kate's username and password.
Insomnia, Anne Kate? Posted by ak (Member # 90) on :
Nope, since Paul can get online more now, I've been keeping something more closely approaching Iraqi time the last few days.
How about you? Where have you been? I used to count on you for 4am philosophy when I was having insomnia. Posted by ginette (Member # 852) on :
I think we have no fur because our skin must be able to get nutitrion from the sunlight.
Posted by ak (Member # 90) on :
Ah, good hypothesis, ginette! I'll add it to the list.
Posted by Duragon C. Mikado (Member # 2815) on :
Whoa whoa, lets not look at this from a Lamarckian standpoint. We don't lose something just because we don't need it, we lose it because it becomes a flaw so fatal that any animal carrying it will die off and eventually those genes won't be reproduced anymore.
I guess people slowly started shunning those w/ fur all over and would only breed w/ baldies??
[ August 06, 2003, 07:41 AM: Message edited by: Duragon C. Mikado ]
Posted by Pod (Member # 941) on :
just by the by, we're not adapted to aquatic life. we are, in fact, very bad at dealing with aquatic environments, or environments which have water near by them.
thats why we have boats.
Posted by twinky (Member # 693) on :
Ah, but we're better with water than apes are Posted by Kasie H (Member # 2120) on :
quote:Whoa whoa, lets not look at this from a Lamarckian standpoint. We don't lose something just because we don't need it, we lose it because it becomes a flaw so fatal that any animal carrying it will die off and eventually those genes won't be reproduced anymore.
Wait just a second. If that's true, why are people being born without wisdom teeth? I don't think wisdom teeth are quite a fatal flaw...but at the same time we don't need them any more, so they're slowly fading away.
Posted by Jaiden (Member # 2099) on :
These are the theorys I remember from class... but I took that class a long time ago and my memory is bad
(BTW human's aren't fur-less, our hair is rather fine, etc. so it's nearly invisible, but it is there)
There's beena a theory floating around that humans are hairless to help with ticks, lice, fleas, etc.
There's a theory that unique human cultural adaptions (fire, shelter, clothing) allowed humans the luxury of ditching their hair.
I believe the most accepted theory is that it was a strategy for cooling the body (African savanna's are rather hot)- that it happenend when we left the forest. (Upright posture and lack of body hair might have made it easier to radiate heat back).
A behavioural ecologist from the U of Liverpool (I can't remember the fellows name, I'm sorry!) said that having less hair doubles the distance we can travel off a liter of water.
And, btw, Ted, there is an aquatic ape hypothesis which says perhaps human's underwent a semi aquatic phase. (Which would explain our improved swimming abilities compared to other apes). But... there isn't much evidence of this and is generally thrown out of the window last I checked.
And, hey, who says only one theory or one idea is correct? I'm guessing it's a combination Posted by Theca (Member # 1629) on :
quote:but at the same time we don't need them any more, so they're slowly fading away.
That's quite an assumption. Are there less people born with wisdom teeth now than there were hundreds or thousands of years ago?
And if so, maybe in the past (before dentists) people without wisdom teeth were considered more handsome due to straighter teeth or fewer pain lines around their eyes. Maybe they had less fatal jaw infections and lived longer/had more children.
Hmm, I have a cousin who developed two extra teeth, and another with two fewer teeth. I wonder which one is more genetically advanced? Posted by Noemon (Member # 1115) on :
I love questions like this! I think about stuff like this all the time.
It strikes me that another mammal that is furless is the elephant. Every surviving species of elephant is hairless (well, as hairless as we are, anyway). Walruses would be another. I'm not sure that that's useful for our purposes though--in the first instance I expect that it's an adaptation to keep them from overheating (due to massive amounts of metabolicly active tissue and a very warm environment), and in the second it's probably a streamlining thing.
If it were a question of getting enough vitamin D, we could expect that in places where there wasn't a fair amount of vitamin D available from available food, people would have to wear less clothing, exposing more of their skin to the light. I have no idea whether this is the case or not.
What is the difference between options 4 and 7?
quote:The tendency to be attracted to certain features in a mate is a heritable trait which is subject to natural selection. The trait of thinking non-adaptive traits are attractive will tend to be weeded out of any population.
I don't know that that's true. The peacock's tail leaps to mind as a non-apaptive trait that has flourished due to sexual selection.
Could it be a trait that is neutral in and of itself, but is linked to some other trait that does have adaptive value? That would be my guess.
[ August 06, 2003, 09:31 AM: Message edited by: Noemon ]
Posted by Amka (Member # 690) on :
I think it is a combination of the heat and water. Look at all the other mammals that have lost their fur and think of what environments they live in. Pigs, Hippos, Rhinos, Elephannts, Dolphins, etc. Not all aquatic mammals have lost their hair, but most of them have. Of these all, only the rhinocerous, that I'm aware of, doesn't at least hang around water. Some elephants are adapted to the desert of Africa, but for the most part they seem like jungle creatures.
One thing we have to bear in mind is that mutation, without intellegent design, is random. In terms of evolution, 20,000 years is not really long enough to do much for someone with a long lifespan and complex genome.
Posted by aspectre (Member # 2222) on :
Northern Europeans ,who get less sunlight, are noticeably hairier than natives who recieve the greater sunlight of the tropics.
I prefer the 'Marathon Man' theory. Humans can run for longer distances than other animals; ie other animals will become exhausted, allowing the hunter to catch them. Humans sweat, which other animals do not, to allow for evaporative cooling while engaged in strenuous activity, such as running. Fur would lessen the amount of sweat that could be evaporated.
[ August 06, 2003, 10:16 AM: Message edited by: aspectre ]
Posted by Noemon (Member # 1115) on :
Don't horses sweat?
Posted by BannaOj (Member # 3206) on :
yes horses sweat.
A semi-aquatic phase similar to hippos and pigs would explain why small children are naturally attracted to mud.
AJ
Posted by mackillian (Member # 586) on :
*snort*
Maybe they just like getting dirty.
Or that nice cool, squishy feeling between your toes...
*goes off to look for some mud*
Posted by ak (Member # 90) on :
Oh some good new theories!
Noemon, 4 and 7 are different. 4 states that skin is sexier than fur so baldies copulate more often and hence have more children. It applies to both sexes.
7 states that females prefer relatively hairless males for no reason whatsoever apart from fickle whims of taste. Hairless dads then give rise to hairless sons who also are preferred for no reason. Sexual selection is something that happens for males only. It concerns traits that are expressed in males only, like the peacock tail and deer antlers and so on. I actually think scientists are missing some very important reasoning about sexual selection which is another subject entirely. I need to publish it, cause nobody seems to see but me, but it's quite clear to anyone who thinks about it who is female.
Duragon, who are you saying is making a Lamarckian argument? I see none here. I'm saying when a trait conveys a selective advantage, it soon comes to predominate in the population. That's a Darwinian argument, not Lamarckian.
Kasie, the selective advantage that comes from losing something you don't need anymore is only about metabolic cost and extra body weight, etc. Assuming some people had large appendices, say, while others have tiny ones or none at all, then the second group uses less of their fuel building something that is of no use, and carries less excess body weight, so they have a slight advantage. Whether people actually are losing their wisdom teeth isn't established but the principle is the same.
Jaids! Good theory with the ticks, lice, and fleas. I'm adding it to the original list for ease of reference.
Also theory number 1 gets a boost from thinking about elephants and rhinos. Other large african mammals like zebra, antelopes, giraffes, etc. that would also get an adaptive boost from being able to run farther or faster with less water are still fully furred so this isn't convincing to me. What else do elephants and rhinos have in common? Is their hairlessness a shared derived trait? They are somewhat related, neh? Neither have any natural predators besides humans, I don't think, but no idea if that would matter to hairlessness at all.
[ August 06, 2003, 11:49 AM: Message edited by: ak ]
Posted by Laurenz0 (Member # 5336) on :
Unfortunately, now ugly people like me, always seem to get married anyway so mwa ha ha ha ha! WERE BRINGING THE RACE DOWN!! Posted by Laurenz0 (Member # 5336) on :
In all seriousness It might have been clothes. The ones with the least fur needed clothes. Perhaps they were considered a status symbol. Kidna like a trophy. The women perfer this. and so the trait gets passed on. Completely based on nothing. but hey.
Posted by ludosti (Member # 1772) on :
I thought that baldness (at least male pattern baldnes) is inherited from the mother's genes, not the father's...
Wouldn't that throw a wrench into the works, as far as "baldness as a reproductive advantage" is concerned?
[ August 06, 2003, 12:01 PM: Message edited by: ludosti ]
Posted by ak (Member # 90) on :
Amka, pigs are fully furred, aren't they?
Looks like we have 2 groups of furless mammals besides humans. Aquatic (cetaceans and walruses), and the other group which consists of rhinos and elephants. We are guessing cooling is the reason for their hairlessness. Do we fit into either of those groups? I'm not at all sure.
I think the fossil record shows that changes are very abrupt with long times of very little change in between. (Punctuated equilibrium.) The experiments and observations of evolution in action (like the gypsy moths, etc.) do show that changes in entire populations can take place very quickly. Hairiness is quite variable, as we can see, and very heritable. I believe 20k years is plenty of time for this trait to change in entire populations if it were adaptive to do so. We do have human subpopulations with beards and those without, for instance, since the last radiation from Africa which was less than 200k years ago. It would be good if we could be sure of that, though. We need examples of other significant changes in 20k years or less that we know of in mammals, particularly in apes. Can anyone supply any of those?
Posted by ak (Member # 90) on :
Otherwise, if 20k years is too short a time to change this trait, then I want to put my money on the hairlessness being a side effect of the general human neoteny. Neoteny means retaining juvenile characteristics into adulthood and humans' major differences from their closest relatives, the chimps, are mainly neotenous. We retain the small jawbones and flat face and the large cranial growth rate of juvenile apes into our adulthood. This is done by mutations in homeobox genes, which control rates of growth and so on. They are the master switches that control when other genes turn on and off. Great apes are all mature by the age of 4 or so. Our lifespan is much longer than theirs. In many ways adult humans are like juvenile apes, and one way is relative hairlessness.
Yet I think 20k years (which is an absolute lower limit... it could have been as much as 100k years) would be plenty of time to adjust this detail to its optimum setting. It's true that Europeans are much shaggier people than Asians, or Africans, isn't it? Does this give us any clues? Native Americans and Australian Aborigines came from Asian stock, as well, didn't they?
Posted by sndrake (Member # 4941) on :
Well, there's another hypothesis that hasn't been considered. It could be that we lost our fur as a result of one of the most successful, long-range marketing plans in our history.
As I see it, there was probably a group of early humans - probably shamans charging exorbitant prices for poultices and relieving pain with birch bark - who foresaw a time when they would come up with a substance to promote hair growth.
But as they looked around them, they saw the market for that would be extremely limited, since a lot of the early humans had plenty.
So I figure they started planting the idea around that skin was sexier than fur. As a result, less hairy males and females were more likely to produce offspring.
And they got what they wanted - male pattern baldness. The descendants of the original marketing geniuses went on to found Pfizer, the makers of Rogaine - who now bombard us with commercials telling men (mostly) how unappealing they'll be to women if they don't regrow some hair.
Then there's that whole thing about the ancestors of Dr. Scholl's getting early humans up onto two feet.... Posted by DOG (Member # 5428) on :
I haven't lost my fur. I know I have it around here somewhere....
--DOG
Posted by saxon75 (Member # 4589) on :
quote:a. The tendency to be attracted to certain features in a mate is a heritable trait which is subject to natural selection. The trait of thinking non-adaptive traits are attractive will tend to be weeded out of any population.
This is not really correct. Witness the large number of brightly colored tropical birds. However, your second observation about sexual selection seems pretty accurate.
Posted by FlyingCow (Member # 2150) on :
Of course, there are always exceptions to the rule. Mexican hairless dogs, for instance, and Robin Williams.
Posted by ak (Member # 90) on :
The brightly colored birds, long peacock tails, deer antlers, and other traits like that are all expressed only in the males. The message they send is "I am so very fit that I can survive despite this obvious handicap". They advertise to the females that, while your sons will be similarly handicapped, your DAUGHTERS will be extraordinarily fit. This proves that the fitness of daughters is more important than that of sons to an individual's reproductive success overall in passing their genes down to future generations. I think this conclusion is inescapable, yet nobody seems to understand that but me. I need to publish this observation.
Posted by ak (Member # 90) on :
saxon, it HAS to be correct. All that's required is for the trait to be variable and heritable, which it demonstrably is. Therefore natural selection will act upon it, without fail.
Posted by asQmh (Member # 4590) on :
It was God's little joke. "Hey, look at that bald critter! I'm gonna tell him he's in my image! :snort:"
Either that or it was universal chemo to get rid of a funky genetic quirk proto-humans had. Like. . . a taste for freakish fruit of knowledge and such. It's just one of those things that it never grew back.
Q.
Posted by ak (Member # 90) on :
Oh, Q, what a GREAT hypothesis! I love that univeral chemo idea!
Posted by saxon75 (Member # 4589) on :
quote:saxon, it HAS to be correct. All that's required is for the trait to be variable and heritable, which it demonstrably is. Therefore natural selection will act upon it, without fail.
Any variable and heritable trait will be acted upon by natural selection, true. However, natural selection and sexual selection often work at odds to each other. A male bird's bright plumage is not an adaptive trait and in fact hurts its chances of survival. That trait should select out, then. However, because of sexual selection--and the reasoning behind it that you supplied--the trait is actually selected FOR instead of AGAINST. But it's not that trait that is adaptive, it's the other traits that are implied by that individual's continued survival: strength, endurance, intelligence, etc, which are all also both variable and heritable.
Posted by Maccabeus (Member # 3051) on :
Ak, I should point out that once such a selective effect becomes established males with the embellishment would cease to be less fit than those without, if one thinks of fitness simply as capability to produce more offspring, because females would prefer the males with.
Posted by ak (Member # 90) on :
Maccabeus, that's what is said, and yet it is a logical error. Fitness is an objective trait. Can he outrun predators? Can he find and consume the highest quality food? Is he healthy and strong? Can he run fast, fly well, etc.? These are the things that go to make up fitness.
Do the chicks dig him? is not the same type question because the shoe is on the other foot here. Here the trait natural selection will be working on is the females' tendency to choose fit mates. Females who choose unfit mates get bred out of the population!!!!!!! This can't be said with enough emphasis, seemingly.
Therefore there must be a different explanation of the paradox of the peacock's tail, the deer's antlers, and so on. And the reason is just this. Such traits advertise the potential for extremely fit DAUGHTERS, despite the handicap that they convey to the sons.
Every such trait, without fail, is expressed in the MALES only. You would never choose a mate who would pass down handicaps to your daughters. If you did your gene line would die out. This shows that daughters count more than sons to long term reproductive success, in terms of replicating the most genes in future generations.
Posted by saxon75 (Member # 4589) on :
The point is that in sexual selection, the females are NOT selecting mates based on fitness. They are actively selecting for traits that have nothing to do with fitness, traits that you'd think would hinder fitness. One biologist did an experiments using birds on the Galapagos Islands. He noted that the males with the longest tail feathers mated the most. So he went and cut the tail feathers off one group of long-tailed birds and attached them to a group of short-tailed birds. He found that the shorn males no longer mated regularly and that the males with the false feathers mated much more frequently. The conclusion, then, is that the females are directly selecting for the adverse trait, and not for the good ones that usually go along with it.
Posted by ak (Member # 90) on :
saxon, you are missing the point. Don't feel bad, though. All the other male evolutionary biologists have gotten this wrong too.
1) The tendency to choose fit mates is a variable, heritable trait.
2) Natural selection will work on any variable, heritable trait.
3) Females who choose mates who are unfit will be bred out of the population.
Because 3) is an inescapable conclusion, we have to ask ourselves how the trait of females-who-dig-long-tailed-peacocks is able to persist in peacock populations? The answer must be that this strategy is a good one. If it were bad it would die out, right?
But how can it be good? It only passes the handicap down to sons only. Meanwhile it advertises that the male is so very fit he can even survive with this huge handicap. What is that saying? Your daughters will inherit his overall fitness. Your sons will inherit the handicap. Therefore fit daughters count more than fit sons.
Read this and think about it and you will see that it must be true.
Posted by ak (Member # 90) on :
Note that all such traits are expressed in males only. If your explanation were true, that selection for unfit mates could just persist despite the unfitness of such a choice, once it set in, then it should be true for both males and females.
Then such traits as being born with no hands or lacking wing feathers or any other sort of deformity might just come into fashion and the trait persist in both males and females, despite the handicap. This never happens, though. All such traits are expressed in males only. Because that explanation is false and mine is the true one.
Posted by saxon75 (Member # 4589) on :
Anne Kate, I wasn't addressing that idea at all. I was talking about this:
quote:a. The tendency to be attracted to certain features in a mate is a heritable trait which is subject to natural selection. The trait of thinking non-adaptive traits are attractive will tend to be weeded out of any population.
Regardless of the reason that the non-adaptive trait is attractive, it is attractive and the females that select mates with non-adaptive traits do not get selected out.
Now, regarding your other idea,
quote:Because 3) is an inescapable conclusion, we have to ask ourselves how the trait of females-who-dig-long-tailed-peacocks is able to persist in peacock populations? The answer must be that this strategy is a good one. If it were bad it would die out, right?
Absolutely. And, as you point out, it's a good strategy because it proves that the males are capable of surviving even though they have this handicap.
quote:But how can it be good? It only passes the handicap down to sons only. Meanwhile it advertises that the male is so very fit he can even survive with this huge handicap. What is that saying? Your daughters will inherit his overall fitness. Your sons will inherit the handicap. Therefore fit daughters count more than fit sons.
I think that this is a bit of a flaw in logic. After all, if the sons were not fit, they wouldn't get to reproduce, right? In fact, I could turn this right back around and say that, since the sons have to be that much more fit just to survive and pass on their genes with such a handicap, having fit sons is more important than having fit daughters. But that has some flaws in it as well, doesn't it?
Posted by saxon75 (Member # 4589) on :
quote:Don't feel bad, though. All the other male evolutionary biologists have gotten this wrong too.
Oh, and was this really necessary? If I'm wrong, I'm wrong. There's no need to turn it into a gender issue.
Posted by ak (Member # 90) on :
I'm only hypothesizing that the reason this is so clear to me and nobody else seems to get it is that I don't have any feminine mystery issues or something. Who knows? Posted by The Rabbit (Member # 671) on :
Anne Kate is completely right on this one.
Consider that features like brightly colored plummage and enormous tales only occur in species where females are only looking for sperm from the males. In species where males are also needed to help care for the eggs or young, one never observes this type of adaptation.
[ August 06, 2003, 08:08 PM: Message edited by: The Rabbit ]
Posted by The Rabbit (Member # 671) on :
I think that the best hypothesis yet for humans loosing their fur is that it is an adaptation to living in the dry plains rather than in the wet tropical jungles. Having no fur (actually fur is not the same as hair and humans truly have no fur) dramatically decreases the amount of water that we humans need to cool our bodies. Therefore, the loss of fur would give a significant survival advantage to early humans living arid regions. All the other apes that have fur live in humid, water rich jungles where water is not a scarce commodity and therefore there would be no evolutionary pressure to develop features to reduce the need for water.
Posted by ak (Member # 90) on :
So does that mean we lack fur for a different reason than elephants and rhinos? Do they sweat from their skins and are they adapted for arid regions?
Secondly, is 20k-200k years indeed too short a time for the baldness to have been reversed, after anatomically modern humans spread out to the rest of the world from Africa? Even during ice ages when fur would have been extremely useful?
[ August 06, 2003, 08:13 PM: Message edited by: ak ]
Posted by saxon75 (Member # 4589) on :
Well, given that hominids have been shown to be tool users since at least Homo habilis (1.6-2.2 million years ago) and that Neanderthals used some relatively advanced tools, probably including clothing (30k to 230k years ago), it seems like body hair wouldn't be particularly strongly selected as a survival trait.
Posted by The Rabbit (Member # 671) on :
Part of the problem with reversal is that humans have essentially stopped evolving genetically and begun evolving memetically.
Once humans developed very large brains and the ability to use tools, their ability to adapt to changing conditions became far more strongly dependent on invention and education than on genetic adaptation. A furry human living in cold northern climes would have little survival advantage over a bald human who had learned to steel the fur from other animals and make it into clothing. The bald human would also have the advantage of being able to rapidly change from cold to warm weather adaptation simply by addint or removing clothes while the furry ape would have to rely on the much slower and metabolically expensive process of sheading and growing fur.
For a species with a long reproductive cycle, like humans, invention allows for far more rapid adaptation than genetic change. So once apes became sufficiently intellegent to adapt quickly to their environment theough invention, evolutionary pressure would have favored the subpopulation who were best able to pass their learned behaviors to their off spring. As a result, rather than regaining the ability to grow fur, humans developed the ability to communicate effectively and live in communities.
Posted by Book (Member # 5500) on :
Maybe some of the more hairless apes had to be pretty resourceful to keep heat in, so they developed clothing. So the smarter, problem solving apes survived and flourished. This might have been stated before and I just forgot about it, though.
Posted by Bob_Scopatz (Member # 1227) on :
Humans don't have fur because early on in our evolution it was discovered that when we had fur, we spent almost all our time grooming each other. And while that's a lot of fun, it doesn't get the furniture moved into the cave, if you know what I mean.
Another reason we lost our fur is that primitive women were all like Martha Stewart and they really hated cleaning up when the whole family was shedding. And of course the men couldn't care less and would scratch and cough up hairballs just about wherever they wanted to. Pigs!
Posted by Book (Member # 5500) on :
How old is Nair? Anybody know?
Posted by Mr.Funny (Member # 4467) on :
Hey! I wanna know why Human lost all his fur!
Posted by Morbo (Member # 5309) on :
ak, I go with reasons 1, 2,4,6,8 from your first post. 1 is self-explanatory. 2,the aqua-man theory is supported by mucho evidence. One thing I didn't see mentioned was that human hair follicles follow flow lines, that is they minimize drag in water. I think that's Morris, but I have source amnesia on that.
4, less body hair is sexier is debatable, but look at the current trend for celebrities to get all body hair waxed off or even permanantly taken off.
6, clothing, is pretty evident and easily supported.
8, less hair=more vitamin D. For this I throw out the tangential data that women in all races are paler on average than men, apperently so they can absorb more D for potential fetuses.
ak, I think 20k years is not enough, 200k may be, but 2 million is more like it for a genetic change like losing fur. But I'm no biologist.
quote:Part of the problem with reversal is that humans have essentially stopped evolving genetically and begun evolving memetically.
Rabbit. A cool sentence. I can see why you get repect for technical issues, Rabbit. Anyone who doesn't understand this should get it explained to them. Computers and electronic media will only accelerate human's memetic evolution.
[ August 09, 2003, 05:38 AM: Message edited by: Morbo ]
Posted by ak (Member # 90) on :
I agree that by far the fastest change is in memetic evolution, but I don't believe that means we aren't evolving physically, too. Just we are being selected for different things these days.
Like here in the states, two of the most prevalent causes of death among young people are vehicle accidents and suicide. So I think that means now we are being selected for good reflexes and a sunny outlook.
Posted by Noemon (Member # 1115) on :
First, and most importantly, we have another new emoticon? We're getting enough of them that we're probably approaching a point where we'd be able to use them as hieroglyphics, and do away with alphabetic writing altoghether!
Seriously, though, ak, you raise an excellent point about there continuing to be selective pressure on a genetic level.
Your argument about the importance of daughters makes sense, by the way. I'm also forced to admit that you do have a point about that being harder for male evolutionary biologists to come up with or awknowledge as true--people always bring their cultural baggage to the table no matter what they're doing or how objective they set out to be. That's why it's a good idea to have people from both genders and as many cultures as possible looking at something like this. De Waal talks about this, I think.
One argument I've seen put forth (maybe even here) that is completely fallacious is that we're selecting for stupidity now, since higher levels of education in women result in a drop in the birth rate. I'm always puzzled when people trot that one out--I mean, first, why would they think that education equals intelligence? Second, intelligence is a much more complex trait than, say, eye color--it's one of those things that crops up in surprising places. Utter morons can give birth to geniuses, and vice versa.
What else? Oh, yeah, Morbo--I agree that there is a surprising amount of evidence for the whole aquatic ape theory. I bought a book on it years ago, expecting to have a good laugh--I thought it would basically be an extended Weekly World News article. I was surprised at how convincing I found the evidence. Unfortunately that was about 12 years ago, and I can't remember the specifics. Can you remember any of the other pieces of supporting evidence for that one? I remember something about our body's efficiency or lack thereof in processing water, but I honestly don't even remember which direction that one ran.
Finally, I'd be pretty skeptical about looking at a cultural trait like women shaving off most of their body hair and extrapolate from that a human universal. More often than not it's a mistake; things like that are so variable, and change all the time. Look at the shift in western society from viewing relatively plump women as the physical idea to feeling that way about rail thin women. Usually there are cultural explanations for that kind of thing. The problem is, when you're immersed in a behavior or tought pattern like that, it feels so natural that it's easy to just assume that it's human nature.
Posted by fugu13 (Member # 2859) on :
The Aquatic Ape hyp;othesis has been largely discredited.
And for the perhaps the best treatment of the subject, go here (linked from the second page I give), then order the book they talk about. The page itself is pro-aquatic ape and goes through some contortions to make it seem not so bad that a group of distinguished scientists came together, went over the evidence, and said while water may have been important to early apes, the aa theory itself is contradicted by the evidence: http://www.riverapes.com/AAH/FoF/FactOrFiction.htm Posted by aspectre (Member # 2222) on :
Yes, other animals have sweat glands. For the same reason as they have oil glands: to save the outer skin layers from death by dehydration. Evolution occurs primarily by modification of preexisting structures. Without those skin moisturizing glands, there would have been no basis for multiplication/adaptation into the cooling function.
Horses have been bred for all of recorded history for transportation, keeping up with man's pace, racing. It's unsurprising that those who survived for breeding should also begin to show similar cooling adaptations. It is also quite apparent that they are still far behind humans: Geronimo managed to beat Pershing because his on-foot warriors routinely outran the mounted troops of the US Cavalry.
Posted by Morbo (Member # 5309) on :
Thanks for the links, Fugu. I had no idea the aquatic ape theory had been so discredited. My anthro is 20+ years outdated.
Moore is a great science writer, I'll have to read some more of his stuff. He really shreds the theory. I loved this passage:
quote:Also, fossil evidence shows the larynx wasn't descended until millions of years after the supposed aquatic phase. Maybe it was a delayed reaction. I do that sometimes; someone says "boo" and I jump several million years later.
Jim Moore critiquing Elaine Morgan's book The Aquatic Ape Hypothesis. From fugu's first link :link Posted by ClaudiaTherese (Member # 923) on :
ak: Well done. Yeah, you should get the hypothesis out there -- once you explain it that way, it's hard to see why this would have been missed before. Seems quite reasonable, but I've never heard even a hint of that line of thought in anything I've read before.
quote:If it were a question of getting enough vitamin D, we could expect that in places where there wasn't a fair amount of vitamin D available from available food, people would have to wear less clothing, exposing more of their skin to the light. I have no idea whether this is the case or not.
Noemon, I'd have to puzzle through the details, but I do know that in the northern US and Canada, with the relatively extended periods of dark over the winter and less direct sunlight, we are seeing rickets in kids who are breast-fed by women swathed in occlusive outer clothing and the hajib. Apparently the mothers are becoming Vitamin D- deficient, and this is being passed on to the babies.
(Wow, I was trying to find the correct technical terms for the clothing, and I found this gorgeous website for Islamic clothing online. How elegant!)
Edit: The prices are astounding, too. Look at the denim drawstring skirt for $35, and the beautiful Berkeley cardigan $40 (it is so katharina, in my mind's picture of her), and I'm in love with the hooded denim hijab (full-length cloak) for $65. Man, I never ever buy new clothes -- can't even remember when I last did, other than for my mother's funeral -- but I might just have to. I tend towards ankle-length skirts and dresses anyway, and these are obviously of very high quality.
*impressed
Edit2: Sorry, it's a bit tacky to rave over new clothing when we have people on this board who are trying to make mac & cheese stretch an extra day. But really, if one must invest in a work wardrobe, these look like good investments in quality.
[ August 19, 2003, 05:41 AM: Message edited by: ClaudiaTherese ]
Posted by :Locke (Member # 2255) on :
Because fur was like, so 40 million years ago.
Posted by ak (Member # 90) on :
CT, that is a great site!
Muslims, please answer this. Would wearing a hijab for non-religious reasons be considered an affront? I'm about to spend a good long time in an Islamic country and the head covering seems practical as well as beautiful. I hope to make friends with families living there and can see there being social occasions that could come up in which I might want to follow local customs. Would this be considered a gracious thing or not? I would not want to wear as fashion, garments which had specific religious meanings, for instance. Just trying to get a feel for that.
Posted by unohoo (Member # 5490) on :
Today's New York Times has an article on this today! You can read it at http://www.nytimes.com/2003/08/19/science/19HAIR.html?th (You may have to sign up with the Times to read this article, but it's free). The article is titled "Why Humans and Their Fur Parted Ways". (It's in today's Science section for those who rather read the print).
Posted by ak (Member # 90) on :
quote: Darwin says: "No one supposes that the nakedness of the skin is any direct advantage to man; his body therefore cannot have been divested of hair through natural selection." He uses this as a setup for his next paragraph, which begins: "The absence of hair on the body is to a certain extent a secondary sexual character; for in all parts of the world women are less hairy than men. Therefore we may reasonably suspect that this character has been gained through sexual selection." Then he goes on to provide 7 long paragraphs of info to support his contention.
...
"The view which seems to me the most probable is that man, or rather primarily woman, became divested of hair for ornamental purposes, as we shall see under Sexual Selection; and, according to this belief, it is not surprising that man should differ so greatly in hairiness from all other Primates, for characters, gained through sexual selection, often differ to an extraordinary degree in closely related forms." Charles Darwin, 1871, Descent of Man, and Selection in relation to Sex. (above from Project Gutenberg's copy of the 1874 2nd ed.)
This is a quote from this site that fugu linked above, refuting the Aquatic Ape hypothesis. It's interesting to note Darwin's view on this, which I had forgotten. Also to notice that he sees this as a sexual selection trait which applies to women.
Posted by ClaudiaTherese (Member # 923) on :
ak, if there isn't someone well-versed in Islam at this site, I think you'd find a warm welcome at Islamway Sisters forum online. I don't post there, but I've lurked for awhile. The general mood is quite generous and kind, and their moderators are quite active in answering questions.
I used to wear a wide black chenille scarf (actually, more like a small blanket) draped over my head and hair while travelling, especially by train. I liked the peace and privacy, and I like the seclusion of the body more than feeling on display. My understanding from reading prior posts on this subject at Islamway is that the modesty of dress isn't considered a practice specific to Islam, but is enjoined of all persons. However, I will defer to those who know much much more than I.
[ August 19, 2003, 03:18 PM: Message edited by: ClaudiaTherese ]
Posted by BannaOj (Member # 3206) on :
This reminds me that I have an extremely funny story involving myself, Steve, Nair and giving a simultaneous bath to two dirty dogs that had rolled in cat poo. Mild nudity was involved, but not sex, obscenity, or bestiality. A combination of things just happened to happen at the same time. I'm not sure if I should actually post the story here on Hatrack or not. Suffice to say, the incident originated the expression among my friends, "Doesn't that just Nair your a$$"
If you want the details (which are very funny) you can IM me at BannaOj
AJ
(this was in response to Book's post way, way up at the top)
[ August 19, 2003, 01:53 PM: Message edited by: BannaOj ]
Posted by Noemon (Member # 1115) on :
I can't use an IM client from work, Banna, but I'd *love* to hear your story! You could email it to me, but I'd say just post it, and delete it if you get complaints (maybe just delete your story, not just the whole thread though).
[Edit] CT--very interesting about the women wearing the hajib having children with a higher than normal incidence of rickets!
[ August 19, 2003, 02:45 PM: Message edited by: Noemon ]
Posted by Morbo (Member # 5309) on :
quote:Usually there are cultural explanations for that kind of thing. The problem is, when you're immersed in a behavior or tought pattern like that, it feels so natural that it's easy to just assume that it's human nature.
Noeman
quote:The message [of a bare-skinned model] — "No fleas, lice or ticks on me!" — is presumably concealed from the conscious mind of both sender and receiver.
a louse researcher, from the above NY Times story. Cultural conditioning is hard to overcome and understand, to be sure. But even harder to overcome is unconscious sexual signalling. But as I said, it's debatable. I have two louse experts (heehee)--can you support the cultural conditioning view? Is there a culture that values excess body hair, especially in females? (Aside: who in their right minds sets out to be a louse expert? It takes all kinds. .) Noeman, fugu's first link pretty well convinced me the aquatic ape theory is dead in the water, or at best in serious trouble.
[ August 19, 2003, 03:01 PM: Message edited by: Morbo ]
Posted by Morbo (Member # 5309) on :
This is slightly derailing, but can anybody confirm that factoid I posted that women of all races are paler than men, presumably because fetuses need extra Vitamin D? I read or heard that last year but have total source amnesia.
Posted by BannaOj (Member # 3206) on :
btw CT and ak, the idea of wearing those head coverings is awesome. They can be very classy.
Ok here goes with the story. You would probably have to see how Steve and I interact with each other in real life in order to completely understand, but we have a great, if a bit unorthodox relationship.
I am very hairy for a female and definitely hairier than Steve (fortunately I'm blonde so it isn't horribly visible.) Out of curiosity because I'd never used the product, I bought some Nair in the roll on variety. As a gag I gave it to Steve. One of the places I was contemplating using it was my derrier. For a couple of days he chased me around the house brandishing the bottle threatening to use it on my posterior as a joke. It got a little bit old to me round about day 3 or 4, but Steve was having such fun that I didn't want to spoil it.
That day we let the dogs out and they came back inside both covered in cat poo. So they went straight to the bathtub. I have one of those shower handsets on a cord specifically for bathing the dogs. Normally I bathe them one at a time but they were so disgusting that I put them both in at once. When bathing dogs the human generally ends up as wet as the dogs so I often remove most of my clothing because there nothing quite like getting wet jean rash while bending over bathing dogs. (These are corgis so they are shorter than most dogs and bending over is even more of a necessity than for most breeds.)
While I'm dealing with the stinky cat-poo dogs, Steve is chasing me around with the Nair bottle. I'm exasperated with both him and the dog situation that I had a brief moment of insanity. I told him "Fine, you can put it on me while I'm washing the dogs since I'm going to be bent over with most of my clothes off and butt up in the air anyway." He starts cackleing with glee, because he never really expected me to give in.
So two 40-lb dogs, myself (nekked) and Steve (clothed) all end up packed into a tiny apartment bathroom roughly the size of an elevator. In order to get into the shower/tub, you had to close the door to the bathroom and the the door clerance was such that you had to be squinched into the space between the toilet and the tub in order to shut it. There was barely enough floor space for a bathmat.
Steve is applying the Nair to my behind and I'm washing Jake when Ciara detected some extra space in that bathroom and decided to make a break for it and leave the tub. One of us caught her and Steve (now finished with the Nair)gets enlisted into dog holding duty while sitting on the toilet seat. He is now pretty sopping wet.
Then my rear starts to burn. I start going, Ow. ow get it off me. The dogs however are only half lathered and not rinsed and if I get in the tub without still holding on to them one will make a break for it. Steve solved the problem by kicking off his shoes and hopping in the tub himself while still holding on to Ciara. I kept holding onto Jake and I stepped into the tub while still loudly complaining about my butt burning...there may have been one or two obscenities and many reiterations of "How on earth did you talk me into this?" We got the shower curtain closed which greatly inhibited any canine escape plans. Then I handed the shower attachment (which sprays wildly when not being held onto) to Steve and turn around so he can rinse off my rear.
As the Nair starts rinsing off, I suddenly panic because I realize it is rinsing right on to the disgruntled soapy canines below, particularly Jake. Jake is a show dog and coat is extremely important and I had sudden visions of trying to explain to his breeder and co-owner how her valuable show dog ended up hairless. I then tell Steve that we've got to rinse the dogs first because they are more important even though I'm gritting my teeth.
At that point Steve just takes off the rest of his clothes and tosses them over the top of the shower because he is already soaked. After that we had a moment where we looked at each other and went, "We are naked, in a shower with two soapy dogs, WHAT HECK IS WRONG WITH US AND HOW DID WE MANAGE TO END UP IN THIS PREDICAMENT???!! Sex is the last thing on your minds, even when you are both naked, when you have a tub full of dog hair involved.
Eventually we did get them both rinsed off and the Nair completely removed from my derrier. There was a towel shortage, but drying them off was uneventful. The postmortem trying to figure out the exact sequence of events that led to the catastrophe didn't really accomplish anything except sendin us and our friends off into gales of laughter.
AJ
Posted by Noemon (Member # 1115) on :
I actually just read the first link over my lunch today, Morbo, and yeah, I completely agree with you about the Aquatic Ape hypothesis not holding water.
About the louse researcher--maybe when he was first looking into a career in science, his advisor tried to disuade him from going into such a rigourous field by saying "son, you'll be a lousy researcher", and the guy just heard him wrong and thought that he was being encouraged to go into parasitology.
As for your actual point, I certainly agree with you that sexual selection is a potent force in any species (well, any species that reproduces sexually, anyway). I'm not aware of any soceity that actually values hairy women over hairless women, but we acutally wouldn't need to go that far to disprove this one, would we? Wouldn't it be enough to find a soceity in with hirsuteness simply wasn't a factor?
I don't have positive knowledge of such a society, but I have long heard that in many European societies it isn't uncommon for women to not shave their legs or armpits. This may be the case, or it may not be. It's also possible that it was the case 20 or 30 years ago, but that cultural shifts have occurred, and it is no longer the case. Does anyone know anything about that? For that matter, does anyone know of any other societies in which hirsuteness simply isn't a factor?
Posted by Noemon (Member # 1115) on :
Banna
Posted by BannaOj (Member # 3206) on :
The scary thing is that every word is true!
AJ
Posted by Morbo (Member # 5309) on :
AJ, LOL Posted by BannaOj (Member # 3206) on :
To derail this thread further, I cut and pasted my own story above, made a few edits, saved it for posterity and e-mailed it it to some non-jatraquero friends. After rolling on the floor for a while they said I should publish it.
The question is, what magazine would take it? I don't quite see it working in a readers digest blurb. And does posting it to a site like hatrack (without which I wouldn't have written it in the first place) constitute prior publication?
AJ
Posted by eslaine (Member # 5433) on :
Great job. Ever consider Blogging?
Posted by BannaOj (Member # 3206) on :
Not really, though I confess I don't know exactly what Blogging entails. I only write if it doesn't feel like work though. I suck at making things up, except occasionally a poem. And my ordinary life while amusing enough, only approaches those levels of wierd a couple times a year.
AJ
Posted by Noemon (Member # 1115) on :
Maybe you could submit it to Dog Fancy magazine? Posted by BannaOj (Member # 3206) on :
Yeah but I might get angry tirades from people who are afraid I dehaired my dog (who was fine btw) Plus that doesn't quite tie in with the Nair, though I could make an analogy to all of the dog hair products that are on the market today. I personally use human Head and Shoulders on Ciara because she is prone to dandruff. It works just fine and is a lot cheaper to buy at Sam's club than any fancy shmancy dog shampoos. It also works great on my dog that doesn't have dandruff too.
AJ
Posted by The Rabbit (Member # 671) on :
Noemon, I've lived in both Austria and Germany and spent quite a bit of time in other parts of Europe. Your are correct. Most European women do not shave either legs or armpits.
Posted by Noemon (Member # 1115) on :
Wouldn't that suggest that "the current trend for celebrities to get all body hair waxed off or even permanantly taken off" in the US is a cultural phenomenon, rather that proof of hairlessness being a sexually selected trait?
Posted by The Rabbit (Member # 671) on :
It certainly does Noemon.
Darwin's arguments for sexual selection miss some very crucial points. First, it is important to note that extreme sexual dimorphism occurs only in species where different genders play dramatically different roles in parenting. In species where both parents perform equivalent tasks in caring for the young, rarely show any type of sexual dimorphism. I am unaware if any species where the gender that carries the greatest parental burden, has notable gender specific ornamentation. It is therefore unlikely that humans lost their fur due to sexual selection.
In order for any trait to be favored by evolution, that trait must be both passed genetically from one generation to the next, and must confer a survival advantage. So let us assume that having fur confers a survival advantage. Then let us imagine that a male appears who has a genetic mutation that causes him to prefer less furry females. As a result, his children would be born to mothers who were less likely to survive. In homonids, if the the mother dies anytime between conception and the child reaching adolence, the child is highly unlikely to live to adulthood. The net result would be that our hypothetical male would have fewer offspring survive to adulthood than his peers who preferred furry females. Because of the nature of genetic mutation, the fraction of the male population that preferred furless females would initially be very low, so the males less furry daughters would have no clear advantage in atracting mates. If his sons inherited his taste for furless females and his daughters inherited their mothers lack of fur, both sons and daughters would be less likely to produce children that lived to adulthood. As a result, this mutation would be rapidly breed out of the population.
Sexual selection can only conceivably occur when the trait being selected is either survival neutral or is linked to a non-gender-specific survival gene.
[ August 20, 2003, 10:04 PM: Message edited by: The Rabbit ]
Posted by The Rabbit (Member # 671) on :
quote:. . . is 20k-200k years indeed too short a time for the baldness to have been reversed, after anatomically modern humans spread out to the rest of the world from Africa? Even during ice ages when fur would have been extremely useful?
I think it is worth noting that humans of European decent are typically hairier than other racial groups and would have been most strongly impacted by the ice age so perhaps their has been some reversal during the past 20k - 30k years.
The issue of vitamin D is an interesting one. It has been noted that racial groups which originate in tropical areas where there is much sun year round, tend to have alot of melanin which decreases their efficiency in producing vitamin D. Racial groups that originated in in northern climates where long winters with little sun and more need for clothing, have less melanin which increases their efficiency in producing vitamin D. The one exception to this rule are the Eskimos but this is the exception that proves the rule. The Eskimos have a diet of fish and seals which is extremely rich in vitamin D obviating any need for sunlight to enhance their natural vitamin D production.
This data tends to contradict the theory that humans furlessness as anything to do with vitamin D production since Europeans are the hairiest race and Eskimos are almost devoid of body hair.
Posted by Wonko The Sane (Member # 2945) on :
[ August 20, 2003, 11:58 PM: Message edited by: Wonko The Sane ]
Posted by Noemon (Member # 1115) on :
Thanks Rabbit, for confirming that there wasn't a flaw in my train of thought, for the input on the whole "hairlessness as a way to increase vitamin D production" idea, and for the further information on sexual selection. Very interesting stuff!
Posted by Bob the Lawyer (Member # 3278) on :
Psst: It's Inuit. Eskimo translates as "Eater of raw meat" I believe. Anyway, it's considered quite offensive.
Posted by ak (Member # 90) on :
Yeah, Darwin's hypothesis sounds all wet to me but I've got a lot of respect for him as a scientist so it's quite interesting to note what he thought and why.
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Banna