posted
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 ]
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posted
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.
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posted
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.
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posted
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.
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posted
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!
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posted
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.
posted
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.
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posted
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.
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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.htmPosts: 15770 | Registered: Dec 2001
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posted
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.
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posted
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 :linkPosts: 6316 | Registered: Jun 2003
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posted
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.
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.
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posted
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).
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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.
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posted
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.
posted
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)
posted
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!
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.
posted
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.
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posted
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.
posted
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?
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posted
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?
posted
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.
posted
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.
posted
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.
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posted
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?
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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 ]
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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.
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posted
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!
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posted
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
