Infanticide and Cannibalism

[Lemur]

More news of the weird, although in this case it's a weird theory. Why do humans lack body hair? Nobody has a good answer. All of the other great apes have lustrous coats, whereas even the hairiest guy at the beach is, by comparison, relatively bare.

The new award-winning theory is weird and creepy, and who knows, possibly correct:

Harris' paper describes Stone Age societies in which the mother of a newborn had to decide whether she had the resources to nurture her baby. The newborn's appearance probably influenced whether the mother kept or abandoned it. An attractive baby was more likely to be kept and reared.

Harris' theory is that this kind of parental selection may have been an important force in evolution. If Stone Age people believed that hairless babies were more attractive than hairy ones, this could explain why humans are the only apes lacking a coat of fur. Harris suggests that Neanderthals must have been furry in order to survive the Ice Age. Our species would have seen them as "animals" and potential prey. Harris' hypothesis continues that Neanderthals went extinct because human ancestors ate them.

[InsaneApache]

Humans have the same amount of hair as chimps, they're just a lot finer. That's what I heard anyway.

[CrossLOPER]

Neanderthals went extinct because human ancestors ate them.[/indent]

Not unbelievable.

[Louis VI the Fat]

Why do humans lack body hair? Nobody has a good answer.

There is an answer: sexual preference.

The first evolutionary mechanism, survival of the fittest, seems clearly out. There is little use for what's let of your visible hair. Try it: don't shave your chest and leg hair and stand outside in minus fifteen degrees - it doesn't really help.
I do believe the second evolutionary mechanism is at work here: sexual selection. You might not think it, but somewhere deep down women dig a nice, furry back on males.
On intuition, I'm not convinced by Rich-Harris' third selection process: maternal preference.

-For a start, male body and facial hair are a product of puberty, it develops at the same time as other reproductive characteristics, which points in the direction of sexual evolutionary mechanisms. (Unless one would claim that our poor homo sapiens children would need to 'hide' their hair from their mothers until they've reached puberty, the age at which kids become independent from maternal care.
-Secondly, there is a clear distinction between female and male hair patterns, which again undermines the first and third mechanisms, pointing to the second.
-Thirdly, the reason for both males and females having thick armpit and pubic hair is only explainable as a means of sexual reproduction: preservation of wildly arousing scents.
-Fourthly, the wide variety of different hair patterns amongst human groups become only apparent at maturity.
It is not predictable from the appearance of a baby what his or her hair will look like. So mothers / parents would've been unable to choose between offspring based on this criterium.

[Rodion Romanovich]

There is an answer: sexual preference.

If there would be a strong enough sexual preference to allow that alone to lead to devolvement of a fur, then chimps wouldn't have hair either. Sexual preference is quite interesting though - basically sexually preference strives to evolve to match what is good for survival, resistance to disease, good match making (to avoid inbreeding and allow genetical variety etc) and good effects for the entire herd. If the sexual preference is drastically different from what benefits survival, the branches of populations with such devolved sexuality eventually self-destruct in favor of those with more accurate sexual preferences, however sometimes the species has such a strong niche that that doesn't need to happen - there are a few extreme examples such as peacocks, but they aren't representative of the majority. I'd say sexual preference is the key to human fur devolution, but not alone and in a single way, but through several indirect mechanisms:
- invention of clothes makes fur unneeded, which means it doesn't matter if the fur devolves
- furs cost a lot of energy and so on to maintain and grow, so if it loses it's meaning, there's a moderate pressure to remove it
- the human brain has evolved/devolved in a way such that we use reasoning rather than instincts even for thinking over things that our instincts would be better suited to. While this transformation into reasoning thought gave many disadvantages it also gave the advantage of more complex interaction (especially during hunting) etc., that it didn't mean the extinction of mankind, but allowed mankind to survive despite taking such an untraditional path of evolution. As a result of this, many thought mechanisms involved in things such as sexual preference would change in an unspecified and rather random way, since the reasoning thought hasn't gone through any evolution seeking to improve partner choice etc. similar to how instincts have. As a result of this, less hair could possibly have been preferred over more hair, as a rather random effect.
- furs create hygiene and infection problems for open wounds, from what I've heard. It would probably improve survival for a species capable of complex reasoning, to not have a fur. The reasoning species would be able to detect the wound, and easily clean it, if it would be visible and not covered in greasy, unhygienic fur. This could very well have provided a survival advantage.

I don't think there's one answer, but rather a matter of several causes and effects working together. What I've described are 4 reasons why humans would have lost their furs, I'm sure there are at least 10 more reasons of major impact. And we can notice that there's still traces left of the fur, which suggests any form of rudiment evolution - either the fur lost it's importance or actively was subdued by being disadvantageous, but not disadvantageous enough to pressure it to go away entirely.

That modern human beings consider furs unsexy is not necessarily a sign that sexual preference was the first and major cause of the fur removal. It would be natural for the sexual preference to adapt to like less hairy individuals, if less hairy individuals were more successful. Again, I'd like to suggest a multitude of factors cooperating, through intertwined feedback loops, together forming the result. I've mentioned 4 that I consider likely, but that by my intuitive, approximate statistics wouldn't be enough to alone cause the effect in such a short time. I'm sure there are more causes.

On intuition, I'm not convinced by Rich-Harris' third selection process: maternal preference.

Agreed. From a game theory and statistical perspective, the individuals born by the same mother aren't really that much different in survival capability. So the amount of resources at hand would probably be much more crucial than the appearance of the baby for making the decision on whether to commit infanticide or not as a means of birth control. However, it's possible that Harris' suggestion could have had some part in devolving the human fur, though I doubt it would have been THE major cause of it.

Secondly, there is a clear distinction between female and male hair patterns, which again undermines the first and third mechanisms, pointing to the second.

This seems to be common for many other mammals than humans AFAIK. The sexes often have very different hair, so it isn't necessarily a sign of anything special that humans too have this.

[ShadeHonestus]

I'd say sexual preference is the key to human fur devolution, but not alone and in a single way, but through several indirect mechanisms:

I would have to disagree on it being key outside of Homo sapiens themselves and the greatest amount of fur devolution occured prior.

- invention of clothes makes fur unneeded, which means it doesn't matter if the fur devolves

- furs cost a lot of energy and so on to maintain and grow, so if it loses it's meaning, there's a moderate pressure to remove it

The pressures for hair loss is anything but moderate. Any conservation of energy whether through heat dispensation or its cultivation as you put it, allows the average female specimen to bear more children in their lifetime, this is itself key, accepted and indisputable. Its been coined in any species as, "evolutionary gold dust".

The other glaring problem with this is that benefits of hair loss occured prior to the enlargement of our brains. We walked upright and in the open, before we developed brain capacity. The ability to walk upright, hair loss, conservation of energy allowed for new models of sustenance and nutrition which eventually allowed for increase and maintenance of brain capacity.

- the human brain has evolved/devolved, etc etc.

Within Homo sapiens the loss of hair from the beginning state of being human to the modern day is incredibly minute. In fact the biggest impact is in hair placement and sexual dimorphism seen in hair patterns. This largely came about as the human brain had more than one function and as the need for surival lessoned, the ability to reason is cultivated. This isn't meaning that it evolved, that capacity was there in homo sapiens, but untapped until survival allowed for it. Early homo sapiens didn't have the time or need to assign value to a potential mates' charming sense of humor rather in their ability to provide.

The varied body hair among populations of people today that have their origin in isolated and independant development supports this.

Also this would include skin color as sexual preference as in the flawed Darwinian theory on human evolution of body hair and race. People suddenly didn't become less attracted to dark skin...it was the onset of diseases due to vitamin D deficiency that led pigmentation differentiation in different climates. The drastic changes suggest that it can only have happened due to survival pressures and not cultural.


I believe a fellow by the name of Miller at New Mexico (State?) University has some interesting inights into the human brain being one of sexual preference over survival and he is not without his critics. However most of his good theory is shadowed by those without a firm grasp on the human evolutionary voyage and who quote his research out of the context of the discipline therefore inviting rabid criticism.

. As a result of this, many thought mechanisms involved etc etc

Advancement of culture, not evolution of species, impact on hair minute, see above

- furs create hygiene and infection problems for open wounds, from what I've heard...etc etc

Goes to conservation of energy see above and previous posts...

[Louis VI the Fat]

Sexual preference is quite interesting though - basically sexually preference strives to evolve to match what is good for survival, resistance to disease, good match making (to avoid inbreeding and allow genetical variety etc) and good effects for the entire herd.

It is very interesting indeed, isn't it?

I am really not well versed in evolutionary biology. Most of what I wrote is based on Jared Diamond's -of Guns, Germs and Steel fame - book 'The Third Chimpansee'. A 'popular' exposition of human evolution. I do remember one thing striking me as very odd, because it went against my intuition and preconceived notions so much: sexual preference can prefer genes that by any account must be considered counter-productive from a survivalist point of view. The mechanism of sexual preference can override the mechanism of survival of the fittest.

Brightly coloured, loud singing birds really do die at a faster rate than their silent and camouflaged competitors from the same species. But this disadvantage is offset by their attracting more mates and out-reproducing their longer living rivals. It is a near suicidal strategy, a strategy of showing off one's superior genes: the attention grabbing brightly coloured birds show that despite this they still managed to outwit and outrun their predators.

In similar fashion, having beatiful, shiny long hair on one'shead is very cost-inefficient and entirely superflous. Again it is a sign of superior genes. One is so healthy, that one can afford this complete waste of energy. It is flaunting one's superior genes.

The former especially, Diamond argues, could be the explanation why (young) human males smoke and drink so much, why they bungee-jump, drive recklessly, do stupid self-destructive things in general.

And it is why I think those Darwin awards have got it all wrong - there is often a perfectly logical evolutionary explanation for all the apparent stupidity they like to mock so much. They should really be handing out Darwin Awards to 'clever' femaleless nerds behind computer screens.

* downs a bottle of Vodka and goes off to the nearest highway to film himself evading speeding cars to show to all the girls tomorrow *

[ShadeHonestus]

The former especially, Diamond argues, could be the explanation why (young) human males smoke and drink so much, why they bungee-jump, drive recklessly, do stupid self-destructive things in general.

Become liberals...

[Lemur]

Become liberals...

It's odd, you'll be going along, making very reasonable and interesting arguments, and then you can't help yourself but indulge in cheap shots at the "liberals." It's sort of surprising, as it needlessly takes you to a lower level. Everybody's free to indulge in attacks in the Backroom, of course, and pointed humor is encouraged, but pointless and unsupported attacks on "the liberals" are just weird and out of date, man. We've just come out of six years of total Republican rule in this country, where the "conservatives" (a loosely-defined term) held every lever of power. And yet there is still a sub-culture of Limbaugh and Coulter listeners who think it's witty and amusing to blame every ill known to mankind on "the liberals" (a loosely-defined term if ever there was one.)

If you want to shout into a right-wing echo chamber (or left-wing, for that matter), there are better venues than the Org.

[Faust|]

The new award-winning theory is weird and creepy, and who knows, possibly correct:

Harris' paper describes Stone Age societies in which the mother of a newborn had to decide whether she had the resources to nurture her baby. The newborn's appearance probably influenced whether the mother kept or abandoned it. An attractive baby was more likely to be kept and reared.

Harris' theory is that this kind of parental selection may have been an important force in evolution. If Stone Age people believed that hairless babies were more attractive than hairy ones, this could explain why humans are the only apes lacking a coat of fur. Harris suggests that Neanderthals must have been furry in order to survive the Ice Age. Our species would have seen them as "animals" and potential prey. Harris' hypothesis continues that Neanderthals went extinct because human ancestors ate them.

This means that the mother spent 9 months being pregnant and risked her life giving birth, and THEN decides whether she will keep the baby or not?

"Harris' paper describes Stone Age societies in which the mother of a newborn had to decide whether she had the resources to nurture her baby."

But she has already expended great resources being pregnant, and has probably been a less productive member for the last few months, costing yet more resources that would have otherwise been available.

I fail to see how there could be such a dearth of resources to allow such a decision about the fate of the newborn to take place, while at the same time the population is so robust that they can afford to abandon a potential new member when much commitment has already been involved in its development.

That cuteness of babies and our inclination to nurture them are linked is plausible, but I've heard that elsewhere.

[ShadeHonestus]

Very interesting article, however after examination it is full of holes and lacks perception from the school of anthropology.

First is the notion that Homo neanderthalensis became extinct because we humans hunted them. Right off the bat he makes a terrible error in calling them ancestors as we evolved from separate populations of what was most likely Homo erectus. However it is unclear if we are cousins or great, great, great cousins 4 times removed as there are gaps in those separate branches. We do know, with a degree of certainty that the divergence occurred about 700,000 years ago. His notion of hunting Neanderthals is problematic from more than one standpoint. First let’s look at Neanderthals and their physiology. For anyone who is familiar with American Football, consider Barry Sanders and his super human ability to move and elude tacklers. Neanderthals skeletal record shows us not the slow lumbering man of the silver screen, but rather a quite robust yet extremely athletic fellow. Indeed to see him on the football field would make Barry Sanders appear in the slow motion caveman. Second the Neanderthal was a cultural animal; they took care of their injured and buried their dead, the latter being both of ceremony and practicality. Third, the Neanderthal had a large brain capacity, even larger than humans, however functionally different they did have limited capacity for learning and understanding. In my and many peoples opinion these factors do not make Neanderthals conducive to human prey.

Second, the loss of body hair is generally accepted as occurring at many different stages along the road of evolution. In fact, the hairy state of Neanderthals is quite doubtful. They would probably have had the same amount of body hair as most modern Northern Europeans. Perhaps the greatest marked state of body hair loss came at the time of Homo ergaster and Homo erectus. This model is supported by a number of factors, heat dispersion (which was a very strong evolutionary factor) parasites, and cultural selection. One primary principle to remember in the evolution of man, is the importance of the conservation of energy. Many of our earliest ancestors such as Australopithecus aferensis and Homo habilis were complete misfits for their environment in functionality, but the conservation of energy due to their physiology was evolutionary gold as it allowed for increased childbearing.

Third is the abundance of Neanderthal extinction models that hold a lot more water. Remember that the zenith of their population was extremely small and this was in decline prior to the Homo sapiens' migration from Africa. The Neanderthals died a relatively slow death in comparison with their numbers. They were in fact having problems adapting to their environment and with the onset of superior competition for resources, they were fast tracked for failure.

In conclusion the hypothesis is largely bunk taking too much for granted and ignoring evolutionary evidence. Now, hair loss within the species Homo sapiens can be attributed to culture behavior such as natural selection, but only to a point. Hair loss even within our own species is, to at least an equal amount, a result of evolution and we can see this in the lack or abundance of hair within the isolated and relatively independent centers of civilization's development.

[Lemur]

In conclusion the hypothesis is largely bunk taking too much for granted and ignoring evolutionary evidence.

Yes, but much more importantly, it's amusing. I particularly like the image of our ancestors eying their Neanderthal neighbors with culinary intent.

[ShadeHonestus]

Yes, but much more importantly, it's amusing. I particularly like the image of our ancestors eying their Neanderthal neighbors with culinary intent.

Yes and I have to admit my own amusement. A few people who I sent the article too within this field of study ranged from "lol" "interesting..." "and my favorite was "Are you sure this wasn't a National Enquirer misprint?". Most of which ended in a line with something to the effect of "with respect to the research and contribution."

[Papewaio]

I thought it would have been the standard Homo S.S. response when encountering a new tribe to either:

a) Trade.
b) Wipe out all the men and children and take the women as mates (even if they or the offspring are sterile).

Plenty of human tribes have got driven into the mountains and away from more fertile lands by larger more cooperative populations. We have done it to each other, so why not to our closest cousins?

[Hosakawa Tito]

Neanderthals went extinct because human ancestors ate them.

Tastes like chicken, hairy, beetle browed, plug ugly chicken. Tough and stringy too.....needs more salt, maybe a dash of A1

[gunslinger]

Neanderthals went extinct because human ancestors ate them.[/indent]

Awesome! Now can we please start a debate about how evil we all are because our ancestors commited genocide against the Neanderthals? This is pure gold. We're ALL guilty of this one. It's just too bad their aren't any Neanderthals around to whine and moan and sue the government for reparations. Then we'd have a real story.

[Adrian II]

Awesome! Now can we please start a debate about how evil we all are because our ancestors commited genocide against the Neanderthals? This is pure gold. We're ALL guilty of this one. It's just too bad their aren't any Neanderthals around to whine and moan and sue the government for reparations. Then we'd have a real story.

Oh crap!...

*hides huge side of Neanderthal beef*

[ShadeHonestus]

Awesome! Now can we please start a debate about how evil we all are because our ancestors commited genocide against the Neanderthals? This is pure gold. We're ALL guilty of this one. It's just too bad their aren't any Neanderthals around to whine and moan and sue the government for reparations. Then we'd have a real story.

Well of course we must further this that it is indeed evil Europeans who did this, and no doubt all their descendants would become American. One major problem and something you never see much of in representative documentaries and pop culture movies and that is that Neanderthals and the early homo sapiens, including those in europe, had dark skin.

Give Hitler a spin in his grave and give the tin hatters who think only brown people get bombed an extra piece of tin foil.

[Ice]

Awesome! Now can we please start a debate about how evil we all are because our ancestors commited genocide against the Neanderthals? This is pure gold. We're ALL guilty of this one. It's just too bad their aren't any Neanderthals around to whine and moan and sue the government for reparations. Then we'd have a real story.

That insurance commercial comes to mind...

[Byzantine Prince]

Didn't you guys see the Colbert interview with that anthropologist/archaelogist? she said we lost our body hair because we started sweating and our skin became moist enough so we didn't get too hot. If you look at any monkey's skin it's perfectly dry even in the tropics. It's not like they need that fur for the cold of the equatorial climate. :P

Also I bet there are several reasons, not just one.

[ShadeHonestus]

Didn't you guys see the Colbert interview with that anthropologist/archaelogist? she said we lost our body hair because we started sweating and our skin became moist enough so we didn't get too hot. If you look at any monkey's skin it's perfectly dry even in the tropics. It's not like they need that fur for the cold of the equatorial climate. :P.

Well that's comparing apples and oranges. Its about the mechanics of dispensing heat. If you take most furry animals you'll see they have many mechanics that humans don't posses for cooling the body, panting, long thin ears, etc etc. That example you give of apes and humans appears as if its a smoking gun to dispute this theory until you study how the two operate differently within their environments. I don't really want to go into the environments and habitats of every stop along the evoutionary ladder and how their physiology adapts on each branch from the divergence from apes. Its best explained that walking upright, sweat glands, and the loss of hair allows homo sapiens to travel much much further on a given quantity of water in every environment than lets say a chimp or a gorilla.

And yes, this is one factor of a few, but this one is golden...

[Navaros]

More news of the weird, although in this case it's a weird theory. Why do humans lack body hair? Nobody has a good answer. All of the other great apes have lustrous coats, whereas even the hairiest guy at the beach is, by comparison, relatively bare.

Humans are not and never were great apes, therefore it is illogical and incorrect to use the word "other great apes" in that statement. The one thing has no such relation to the other.

Upon reading the crackpot idea quoted in the original post, I see that Harris makes the same error.

[Faust|]

Humans are not and never were great apes, therefore it is illogical and incorrect to use the word "other great apes" in that statement. The one thing has no such relation to the other.

Upon reading the crackpot idea quoted in the original post, I see that Harris makes the same error.

They are. All of them are in the same family I believe.

[ShadeHonestus]

They are. All of them are in the same family I believe.

Yes, its Hominidae a sub family of Hominoidea where the other branch is Hylobatidae. Now there was at one time a consideration of a third family Pongidae which leads some to the confusion of human's classification of great apes, but Pongidae is a dead taxonomy after further advancements in DNA tech shows the relations clearer. There are of course brances of Hominidae itself, but everything within it are considered great apes.

[Ja'chyra]

Hmm, 2 thoughts on this.

1. Wouldn't this mean that the bible is wrong? Whodathunkit.

2. If all modern humans originally came from Africa would that mean that Africans are really to blame for slavery?

[Fisherking]

@ShadeHonestus

Some article I read said they thought they had found musical instruments of some sort... (maybe flutes) in association with Neanderthal remains. I can't remember clearly but I had also thought that adal-adals may have also been used by them. Now of course they had been around longer than we had at the time, but what exactly were the tools they just couldn't comprehend the use of that we had advanced to by that date?

The more I have learned about them…or at least the thoughts and theories of their culture/life style the more I wonder why they actually went extinct. They surely would have kicked our butts in a fight and seem more like people to avoid rather than pick fights with. I can't see having him as a favored item on the menu.

[Sjakihata]

Humans are not and never were great apes, therefore it is illogical and incorrect to use the word "other great apes" in that statement. The one thing has no such relation to the other.

Upon reading the crackpot idea quoted in the original post, I see that Harris makes the same error.

And the earth is only 6000 +/- years old ....

[SwordsMaster]

This is some thread title to stumble into just out of bed... Damn!

It is less creepy than i was beginning to imagine though.

What i am not sure about is why not throw all those theories together? I mean at this stage we all know that there is no singular reason why, therefore it must be a combination of reasons, and the more the merrier...

[BDC]

I read somewhere humans lost hair because they stood upright, so got a pleasant breeze to keep cool. Hair is kept on the head because otherwise you get really badly burned.

In other news pubic lice lept from gorillas to humans. What ever were our ancestors up to...

[ShadeHonestus]

I read somewhere humans lost hair because they stood upright, so got a pleasant breeze to keep cool. Hair is kept on the head because otherwise you get really badly burned.

The breeze only helps because, of course, sweat glands. Hair is only covering a small portion of the body surface area that is likely to get burned. There are theories that the retention of hair on the head, beards in men, and hair other places were retained as a display of sexuality in early man.