Why did we lose our fur?

[ballzac]

The problem for me with that theory is that our thoughts are also shaped by biological and cultural evolution. If it is better for us to have hair, then the males who are attracted to women with less hair will produce offspring with a poorer chance of survival. A tribe of people who think that hairy women are unattractive, will have a poorer chance of survival than a tribe who don't, because they will produce more offspring that are less suited to their environment. The point is that, although "selective breeding by subjective attractiveness" may play a part, it will be driven by the environmental factors that determine whether or not we are better off being hairy or not hairy.

[tripsis]

There are countless examples of sexual selection selecting for traits that are detrimental for survival to the individuals that carry them, but confer greater chance of matings (e.g. massive antlers, unwieldy, large feathers, bright colours, etc. Even if having no hair/fur reduced chance of survival in individuals, it may well have increased chances of matings, thus the genes for hairlessness could have come to dominate via sexual selection.

[ballzac]

True, but I don't think those examples are simply a matter of 'taste'. I'm not saying that sexual selection doesn't occur, just that there has to be a benefit for this process to occur. I don't know the ins and outs of peafowl mating, so I don't know all the pros and cons of the peacock feathers, but I'd bet that the benefits outweigh the costs. Likewise, I don't think human loss of hair could have occurred simply because males fancied hairless females. I think it's gotta be a lot more complex than that.

DISCLAIMER: I am not an evolutionary biologist.

[Distracted]

A disclaimer I should've put in my post.

If we did lose our fur by selective breeding then it would've been quite early on and we'd all be decended from the same shallow gene pool.

it's ok ballzac I don't think any of us are 'qualified' to be discussing this but it's fun to bounce ideas around. Especially about such a novel topic.

[Marcel]

Some of you guys are confusing evolution with Lamarckism.

Quote: "[Lamarckism is the belief that] individual efforts during the lifetime of the organisms were the main mechanism driving species to adaptation, as they supposedly would acquire adaptive changes and pass them on to offspring." One alpha male's (or a whole tribe's, for that matter) predilection for shaved babes does not lead to a process of natural selection whereby we shed our hair in an effort to appear more fuckable to the socio-cultural flavour of the month. There is no exo-human (pardon my neologism) benefit to the species as a whole. A commonly used example to illustrate this fallacy is that the Jews, who have been circumcising their males for thousands of years, are not born with penises any different to other Homo sapien males, and they never will. Don't get me wrong; I'm all for the quirky and unorthodox corners of science, way outside the mainstream, but Lamarckism is pretty silly and banal stuff. I like a little imagination behind my pseudo-science... Sheldrake's theory of Morphogenetic fields, anybody?

Furthermore, I have a second-hand bookstore and I come across a lot of old erotica. And I mean a lot! Lots of books from the 19th century, but also contemporary collections exhibiting the history of erotica throughout the world (it's a gigantic area of art publishing). Outside of a few examples during the Renaissance, and in pre-Meiji restoration Japan, and in the work of some of the Dutch Masters, it really isn't until the mid 20th century, in the Anglophone world specifically, that hairless women are considered in any way attractive.

[Psylo]

Something to read for those with some time on their hands. Start at Page 7.

ADAPTIVE ASPECTS OF HOMINISATION: LOCOMOTION, MANIPULATION AND THERMOREGULATION

Also, does anyone know how to find scientific journals online without paying for them ? The following could be of interest to this discussion:

http://www.sciencedirect.com/science/article/pii/S0047248484800792

http://www.sciencedirect.com/science/article/pii/S0047248485800919

[ballzac]

Marcel, I don't think that's the argument that's being used. I mean, if (for some reason) every male suddenly finds hairy females unattractive, then over evolutionary timescales the genes of the hairy women will not be allowed propagate to successive generations, but the genes of the hairless women will. I don't see anything Lamarckian about that. It's just the "for some reason" that bothers me. There must be a reason for such a shift across an entire population, if such sexual selection is even considered to be a possible contribution to hairlessness.

Edited May 29, 2011 by ballzac

[Psylo]

Some of you guys are confusing evolution with Lamarckism.

 

I knew there was a theory out there to back up my ridiculous past statements!! I have quite small nipples, and have told various lovers over the years who have commented that I am on a one-man mission to 'evolve out' my pink protuberance as they serve no purpose to a male human.

Why do men still have nipples ?

[tripsis]

Well, I'm not saying that sexual selection is actually the main, or only cause, but I am saying that it shouldn't be underestimated. Stags that are adorned with massive antlers have to eat a lot more than the females with small or no antlers. There is great cost to carrying those antlers, yet females choose stags with large antlers as they seem to correlate with good genes. With that in mind, facial symmetry in humans also appears to correlate with good genes. Nowadays, as everyone is just about hairless (we're not discussing bald pussies here after all), hairlessness probably doesn't correlate with good or bad genes, but it's possible that back when we were still furry apes, that it could have. I'm just hypothesising here, not stating this as fact. Merely putting forward a possible cause for how we became the naked apes we are.

If we did lose our fur by selective breeding then it would've been quite early on and we'd all be decended from the same shallow gene pool.

Well, everyone who has descended from ethnicities (not races, as there is not enough genetic diversity amongst humans for us to be divided into races) above sub-Saharan Africa has descended from around 20 or 30 individuals (or pairs? ...I forget) which made there way out of Africa several thousand years ago (I forget the figure, maybe 60000?). Those people who descend from ethnicities below sub-Saharan Africa have more genetic diversity than the rest of the world combined. So most of us do descend from a shallow gene pool, but that would have been long after we lost our fur.

Marcel, I agree with ballzac, the idea of sexual selection causing hairlessness is not Lamarckian. If hairlessness is consistently selected for over many generations, hair will eventually disappear.

Why do men still have nipples ?

Evolutionary relic. No need for them do evolve away completely.

Edit: typos

Edited May 29, 2011 by tripsis

[Distracted]

Some of you guys are confusing evolution with Lamarckism.

Quote: "[Lamarckism is the belief that] individual efforts during the lifetime of the organisms were the main mechanism driving species to adaptation, as they supposedly would acquire adaptive changes and pass them on to offspring." One alpha male's (or a whole tribe's, for that matter) predilection for shaved babes does not lead to a process of natural selection whereby we shed our hair in an effort to appear more fuckable to the socio-cultural flavour of the month. There is no exo-human (pardon my neologism) benefit to the species as a whole. A commonly used example to illustrate this fallacy is that the Jews, who have been circumcising their males for thousands of years, are not born with penises any different to other Homo sapien males, and they never will. Don't get me wrong; I'm all for the quirky and unorthodox corners of science, way outside the mainstream, but Lamarckism is pretty silly and banal stuff. I like a little imagination behind my pseudo-science... Sheldrake's theory of Morphogenetic fields, anybody?

 

That's not quite what I was putting forth.

This is how I see it, well at least it's fun to imagine.

Tribe A is ruled by Fred.

One day Tribe A encounters Tribe B who has a woman born with a genetic abnomality whereby she only produces hair on her points(or thereabouts). Fred is amazed at this woman and has Tribe A kill off Tribe B except for the woman. Fred thinks the woman is a sign from god and mates with her, he then decrees that any child born from the woman is born from God and as such all other women will bear evil children. He then eradicates the other women and bears many children, has sex with children etc.

I think of it more like caveman eugenics than natural selection.

[tripsis]

I think of it more like caveman eugenics than natural selection.

[ballzac]

A commonly used example to illustrate this fallacy is that the Jews, who have been circumcising their males for thousands of years, are not born with penises any different to other Homo sapien males, and they never will.

 

Also, I think this may not be true. Say every now and then a person is born with a genetic mutation that affects their foreskin. Perhaps this foreskin will have a form that causes its owner to contract more sexually transmitted infections. These genes will be selectively bred out in cultures that do not circumcise their children, but given enough time, I don't see why a Jewish population will not potentially evolve to have foreskins of a different form. True, I have not heard of this being true at this stage, but thousands of years is not much in the context of evolution. Lets see what happens in 200 thousand years if Jews continue the practice of circumcision and do not interbreed much with other races.

[Rabaelthazar]

Thanks for all the discussion so far. A special thanks goes out to all who spoke about vaginas and a special no-thanks goes out to Meeka for that photo she posted.

Good brain food.

[random]

Haha.

[Marcel]

Marcel, I agree with ballzac, the idea of sexual selection causing hairlessness is not Lamarckian. If hairlessness is consistently selected for over many generations, hair will eventually disappear.

 

You're absolutely right and I agree with you there, but as ballzac says, the question of "why?" remains. What I mean is that it's not Lamarkian to suggest that hairiness can be bred out, but it is Lamarckian to suggest that a predilection for hairless women and men can be bred into the species. For example: you can breed a hairless dog, but you can't breed a dog that will only breed with other hairless dogs. Darwinian evolution has its fair share of holes and light-hearted leaps, but one thing that central to his approach is that selection is dictated by the necessity of survival. I find it dubious that aesthetic tastes can be hardwired into a species.

So I guess we're back to the starting point. Why the hell are we hairless, and more crucially, why was the father of modern evolution so damned hairy?

[tripsis]

While my suggestion wasn't implying that a predilection for hairlessness has been bred into us, cultural norms can replace genes as memes (to a degree). If it becames the cultural norm to view hairless as attractive, just like these days in Western culture, skinny is viewed as attractive, then effectively (if not literally) a predilection for hairlessness may be bred into us.

[The Dude]

...I know that this whole discussion is about the assumption that we did evolve from primates, once everybody gets over that version of a genesis myth here's another, genetic modification.

[tripsis]

It's a much safer "assumption" than any other alternative.

[WoodDragon]

I mean, if (for some reason) every male suddenly finds hairy females unattractive, then over evolutionary timescales the genes of the hairy women will not be allowed propagate to successive generations,

If hairlessness was a sexually selected trait operating under this pressure, then males would still have their body hair and females would not, compared to pre-human species. I'll get back^* to the obvious greater body hair in contemporary human males in a minute...

For humans to lose their hair through deliberate mating preference, such a choice would (as has already been noted) need to confer a survival advantage that outweighs the mere 'undesirability' of hair.

In a sexual selection context, there is no obvious reason for female rather than male humans to pay a fitness price by losing hair, when they are the primary carers of infants. It's important to remember that where sexual selection occurs, the selecting gender is almost always (if not always) the gender that puts most energy into reproduction. If there was a mere (non-sexual selection) thermoregulation benefit, then the implication is that pregant females are more prone to overheating, which is unlikely as they are also more sedentry at this stage. Therefore evolving hairlessness by male choice would likely be pushing female fitness in a negative direction, and as females are the heavy energy-investors in reproduction this would work against such choosy males. And in a non-sexual selection context, selection of deleterious traits also rapidly disappears.

Further, one has to be careful to speculate in the first place that prehumans would find hairlessness 'sexy'. That is purely a cultural affectation, and as Marcel has pointed out an attraction to hairlessness is a very modern and sporadic trend.

This leaves the option that:

1) females, as the sexually-selecting gender, selected hairlessness in males, which somehow resulted in greater hairlessness in females

2) hairlessness was selected by non-choice factors.

If (1) was correct, then ^*males would not develop secondary (facial, chest and back) hair at puberty. These (sexually-selected) characteristics are developed as signs of virility/fitness, and thus indicate a healthy individual in the face of carrying a penalty. Secondary hair is controlled by testosterone, which also besides conferring enhanced muscle/skeletal growth slightly suppresses the immune system. In a 'natural' environment a successful and fit individual advertises his superiority by carrying such energetically-expensive adornments and still surviving - the same as a peacock's tail.

Note that sexullay-selected adult body hair in males has never regressed back to ape levels - up until fairly recently (on evolutionary timescales) doing so would have overheated hunters, leading to a risk of death, and thus demonstrating that there is a hairiness limit in hunting humans. However, there does seem to be more body hair in Caucasians than in equatorial races, which would seem to demonstrate that acquiring more secondary hair at high latitude is not as costly as it is in low latitudes - which makes sense.

All this might be a bit confusing, but without spending hours typing a more detailed explanation, the upshot is that both sexual and non-sexual conscious choices for hairlessness cannot be demonstrated as parsimonious explanations, and indeed they are explicitly contradicted by real-world patterns of hair development.

So, this gets back to (2), which leads back to the persistence/endurance hunter model of losing hair in a hot climate. Basically, as I said in my previous post, as humans became better able to use their brains for language and tool-using, they were able to stand upright and chase prey down over long periods of time, with the concommitent trait of losing hair to avoid overheating. Psylo Dread's first link at #31 discusses all this in great detail, so it really is worth the read.

Having said all this, there are modern sexually-associated preferences perceptible in human hairiness preference. Males generally like long hair in females - it is used as a measure of health, and thus frequent literary reference to "long, flowing, glossy locks". Modern females often have their own access to energy resources (via money) and thus revert to the next best characteristic in males - youth, with its attendance absence of hair. There is a tension going on here though, because if a male is very rich, many females recognise resource availability in such males through their fame and wealth, and will choose them even if they are old... it gets back to how old versus how rich, and the Eddlestons and Hefner's of the world exemplify this.

One interesting hair choice that seems to reflect the old/young tension is male pattern baldness. I suspect that MPB is a sexually-selected trait that shows fitness success, because in a 'natural' environment it exposes the male to a penalty of a cold and sunburned head. It's a bit light a gorilla's silver back - to get it the male needs to be older, and thus 'proven' to be fit. In today's women some love baldness, but many do not - it is likely that competing proofs of male 'fitness' come into play with female wealth, amongst other things. Remember, both male and female gametes (sperm and eggs) deteriorate over time, although more quickly in females, so choosing a younger mate can compensate for slightly less genetic fitness in other aspects.

It's all a game of survival in the end, and a matter of competing choices.

Why do men still have nipples ?

Men have nipples because the female body is the default pattern/template. The y chromosome is an "if" modifier, and the X is the "else" alternative. In this type of gender determination, nature is basically Boolean. Men have never suckled young, so it's not ever been a matter of 'losing' nipples. Some people have big ones, and some have little ones, in both genders. It's just a statisitcal distribution thing. For men to completely devolve nipples risks their daughter losing the ability to lactate, so evolution probably won't select out male nipples any time soon!

[WoodDragon]

Further to my point about female humans being the sexual selectors in our species, one only needs to consider modern mating habits. Most men will root anything at any opportunity; they often do not invest heavily in child rearing (and certainly not in fœtus growing) and for them spreading the male glory around is better than being fussy. Most females on the other hand have to be wooed and coddled and coerced into a relationship, especially their first few relationships. In such a milieu male preference for hairlessness would completely evaporate - hairy females would jusrt become less choosy, and be quickly knocked up.

Interestingly, many females have a habit of initially mating with virile, aggressive, and otherwise strong and fit males when younger (bad-boy choice syndrome), and later partnering with older, less fit, but wealthier or more emotionally stable/passive males. In such cases the latter males are basically cuckolded, and in some cases deliberately so by adulterous females, but the cuckcolded males' 'reward' is a slightly lower but still existent opportunity for having children, where they would otherwise have none at all. The female gets to have some or even most of her kids fathered by a rampant male, at the price of perhaps having a less rampant kid in the mix.

It's a tension between hawks and doves, and in evolutionary terms it is a tension that survives for many generations.

[WoodDragon]

On the nipples thing, it's salient to understand that many characterisics, such as the formation of nipples, happens in fœtal development before the genes on the y chromosome that determine 'maleness' kick in. Thus the human development pattern means that the nipples are already there waiting for the sex chromosomes to tell the fœtus what gender it is.

For males only to lose nipples would require such a profound rewiring of the genetic blueprint that it is unlikely to ever happen - such a rejigging of genes risks far too many deleterious rearrangments when there is no significant energetic cost to having the breast buds just waiting for other genes to tell the body whether breasts are required or not. It would be a very inefficient evolution for something that has no perceptible fitness benefit.

Of course, one of the consequences of this fall-back approach is that sometimes signals are mixed up. Alcohol (amongst other things) can mimic the hormonal signal that tells a breast bud that girly puberty is happening, and hence the appearance of man-boobs that disturbs so many blokes, especially when their own testosterone levels decrease a bit with time...

[WoodDragon]

As I am waxing on about evolutionary traits, I'll throw a few curly comments into the mix...

1) Intelligence is responsible for the very high cost, to females, of fœtus/child care.

2) The high cost of offspring care makes females largely the sexually-selecting gender in humans.

3) Females invented male aggression, strength, and war, and by their focus on child-rearing they also invented spacial/mathematical ability in men as men became the hunting gender.

4) Men invented boobs and hips in women, partly because women invented disguised œstrus in themselves.

5) Men probably invented the functioning clitoris (the clitoris itself is the developmental prototype-penis). That men invented it probably explains why it's so damned hard to operate.

6) As I mentioned above, women probably invented male pattern baldness, which probably explains why so many women do not like it now.

I'll leave it as an exercise for the intellectually curious to work out why these statements are so!

Edited May 30, 2011 by WoodDragon

[The Dude]

Very interesting posts WoodDragon! I appreciate you spending time to explain that for us!

It's a much safer "assumption" than any other alternative.

 

"safer"? Where's the danger in entertaining alternative theories. As long as one doesn't pin down their theory of reality anywhere it really doesn't matter.

There is much evidence in support of the theory we are a genetically modified race species.. it's all in our convoluted, maladapted and otherwise messy dna, our bones and muscles are pissweak in comparison to other primates, plus there's the whole lack of fur thing, we don't have primate eyes, we do not seem to be a part of the natural harmony on this planet at all, we have all these birth defects like no other living thing on earth, which could suggest our genome has been tampered with and is not entirely suitable here, not of this planet, why we cannot really adapt to our environment. Then there's other circumstantial evidence of manipulation from higher beings (Extra Terrestrial or Extra Dimensional) in visions, myths, art, religious texts and iconography ...and footage of Yeti's (what Neanderthals evolved into instead of us).

I like the idea that perhaps alien(novel potentials) intervention can be of a higher dimensional order... erm.. by that I mean that perhaps the genetic modification is of a more subtle mechanism than our physical tools can do. At the same time the "evidence" for is is also the messed up dna that could of happened with inaccurate splicing.

I'll need to get some youtube videos as conclusive internet proof.

...Anyway, as far out as the theory is, I like it. The very concept of an alien other in a universal (singular) existence, it's like a program in the matrix designed to create self awareness from it's dissonance from the harmony of nature(totality), by having an outside point of reference we are god finally able to look in the mirror, by stepping back, outside the body of god, we are out of body, ecstatic.

It is from isolation and disconnection (alienation) that we can feel the bliss of the reconnect. Where nature is a harmonious unity, we are stuck in duality, we are lost to find ourselves, we have fallen from the dizzying heights where all there is is white light to make our way back, to walk the path, to experience the journey, to witness the beauty, without this dynamism, all there is is all there is and that's all there is.

...Thanks for the opportunity to rant a bit about unsubstantiated theories about everything and nothing.

[edit]

It seems "logical" to me that if we live as a network of subjective consciousness in an undefinable shared reality, that the further abstractions of our consciousness (higher dimensions) would also share our consciousness, that these angels or demons (or aliens.. whatever nomenclature your mythology prefers) are a holographic extension of ourselves, like I am of you and you of me. Just a theory.

Edited May 30, 2011 by The Dude

[tripsis]

You raise some good points, as usual, WD. As I said before, I wasn't suggesting that sexual selection may have been the only, or even main, driver of us losing our fur, but I think it's plausible that it could have worked in conjunction with other non-choice factors.

That men invented it probably explains why it's so damned hard to operate.

Hard to operate? I've never met a clitoris that hasn't responded enthusiastically to stimulation. Maybe I'm just lucky, or women these days are not afraid to express what they want?

There is much evidence in support of the theory we are a genetically modified race.. it's all in our convoluted, maladapted and otherwise messy dna, our bones and muscles are pissweak in comparison to other primates, plus there's the whole lack of fur thing, we don't have primate eyes, we do not seem to be a part of the natural harmony on this planet at all, we have all these birth defects like no other living thing on earth, which could suggest our genome has been tampered with and is not entirely suitable here, not of this planet, why we cannot really adapt to our environment. Then there's other circumstantial evidence of manipulation from higher beings (Extra Terrestrial or Extra Dimensional) in visions, myths, art, religious texts and iconography ...and footage of Yeti's (what Neanderthals evolved into instead of us).

Firstly, we're not a race, we're a species. The concept of the "human race" is both erroneous and misleading.

Alright, "safer" was a bad choice of word. Plausible would have been more suitable.

As for "evidence", none of it strikes me as anything I would call evidence. Noncoding DNA ("junk DNA" or "otherwise messy DNA") exist in more than just humans. Does this mean than any organism with noncoding DNA has been tampered with by aliens?

How do we not have primate eyes?

As our brains are so large and our intelligence so great, we have no need for strong muscles and bones. To evolve to keep just energy hungry traits would be detrimental to us. Our brains are better off with the the energy that would otherwise be required to feed bulkier bodies.

But as you know, people believe what they want and will make of information whatever they can to suit their beliefs. Alternative theories are interesting, but they don't hold much credibility to me.

[The Dude]

Yeah, I'm no geneticist, apaprently there are tell-tale signs of manipulation within our genome, beyond there being "junk dna", so what I mean is the "mess" is apparently different to regular "messy dna". I'll find a presentation I was watching on youtube that presented all the evidence for intervention in the development of our species, or out-right creating a novel hybrid species from various other species and genetic modification.

Now the points you make about our human brain replacing the benefits of strong bones and whatnot, good point but the evolutionary timescale between our "ancestral" species and the one we are part of now is often seen as too short to be the effect of evolution, 3 words: "The missing link". Positing that an alien other (not harmonious with our ecosystems) GM'd species on this planet as an experiment (or attempt to harmonise the alien consciousness with life on earth... or to steal our gold) seems a reasonable explanation for our disharmony within the natural world on this planet.

Science and genetics and evidence twisted and filtered to fit an assumption aside, what do you think of the story? The spiritual significance of an alien other creating change through increasingly novel influences? As far as metaphysical frameworks (myths) go, I like it. Of course it's a conveniently placed answer where there is now a mystery (except for all of societies myths regarding genesis), having said that I like the answer as itself a mystery symbolised by the forever alien other.

Edited May 30, 2011 by The Dude