Why did we lose our fur?

[WoodDragon]

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?

Don't get me wrong, I think I have my Advanced Certificate in Operation in this department, but I have met many blokes who don't even know where to find it! Seriously, most blokes are a bit deficient when it comes to this area - so to all those who don't know how The Button works, pull your socks up guys!

Although, having said that, some I know some girls have been so screwed up by religion or abuse that the connection between the brain and the lovely bits have been rendered inoperative, which is a tragedy of Greek proportions.

It's all academic for me ATM though, because I've been a single dad for three years, and that's the best girly anti-aphrodisiac I know of!

Yeah, I'm a Roman sandal...

[tripsis]

I guess we have very different ideas of what we consider to be a reasonable explanation. The idea of aliens coming to earth, genetically modifying us for some inexplicable reason (or to steal gold!!), is completely absurd to me. I'm too cynical to take up a theory like that without there being mountains of evidence to back it up. Not enough of a believer, of any sort. It's certainly an entertaining idea, but I don't find it credible in the least.

We are still know very little about the world around us and the way things work, evolution included, but it appears that evolution can occur much quicker than previously thought. Our history from "primitive" ape to modern human has certainly occurred quickly, but not so quickly as to be outside the realms of scientific plausibility. Missing link? Well there have been numerous other hominids which came before or live along side us while we became what we are today. None of them are the missing link, but it goes than evolution of hominids (not just ourselves) happened pretty quickly. With such an incomplete fossil record, it's probably unlikely that we'll even find a missing link.

I have a problem with YouTube videos in that anything presented as evidence in them is unverifiable. They don't list references (or if they do, they are often pretty dubious sources) and are not peer reviewed. I could easily make a YouTube video claiming that sexual selection is the primary reason why humans lost their fur, present some points which appear like hard, scientific facts, reference some dubious sources (for example, write up a paper myself and post it elsewhere on the net) and soon have a whole following of ignorant people that believe that what they've seen in credible fact. I'm interested in seeing this video you mention, but I'm doubtful it'll provide much in the way of credible evidence.

It's as you say, you like the idea, so you're going with it, which is essentially what I was saying before, people believe what they want to. But I don't want to delude myself because it's convenient. Back in year 11 I wrote somewhere in my art book "I'd rather live in a hell full of truths, than a dream full of lies". I still feel that holds true. Who knows, you could be right, but I'll stick with science. Questions of the metaphysical/spiritual are too intangible to be answered with any ease, at least for me.

[tripsis]

As an aside, I'm reading a book on neurology at the moment. I find two point the author made quite interesting.

1.) "In fact, if you zap the right angular gyrus with an electrode, you will have an out-of-body experience."

2.)Patients with temporal lobe seizures believe they experience God.

To me, this is pretty strong evidence that what many consider to be spiritual experiences is simply the brain not working as it should, skewing perception of what is real and giving a (potentially) false picture of the world around them.

[tripsis]

Although, having said that, some I know some girls have been so screwed up by religion or abuse that the connection between the brain and the lovely bits have been rendered inoperative, which is a tragedy of Greek proportions.

I've heard about individuals like that before and it is indeed a very sad state of affairs. I've known girls who have never had orgasms too, which I found very difficult to understand, but never had the opportunity to see if I could change that (not that I'm suggesting I'm anything special, but it could be as simple a matter as having someone who actually cares).

Edited May 30, 2011 by tripsis

[tripsis]

Oh, also...

It's all academic for me ATM though, because I've been a single dad for three years, and that's the best girly anti-aphrodisiac I know of!

My heart goes out to you Woody. Good things come to those who wait (I bloody hope that's actually true; I have vested interests in it being so too!).

[The Dude]

Yeah I can understand that. It's not so much an answer (the answer is the mystery, that being the definition of alien), as it is a model for interpreting reality, a myth of a numinous presence, the self forever projecting a sense of other out of what is singularity. God is divine, dividing the one into two. First there was the word, we interpreted many words from it.

My trip at the moment is concerned with symbolic or metaphorical truths that manifest through a transcendent connecting of disparate dots, which invoke a meaningful multifaceted manifestation of magical moments in mundane material reality (read some Jung). A cause and effect material world created by transcendent spiritual symbols with a fractal or holographic self similarity viewed differently from different angles of interpretation, them all being true. If the mechanisms of the subconscious were understood they would seem to be a very technical science, something beyond our realm of understanding, something alien.

I guess it's just another way of seeing the world. What I mean is that random mutations causing evolution is as much an assumption as an unseen influence which is intentional -I think they are two sides of the same coin and what was once random may have always been order from a different perspective, ie: peak experience full on determinism. Of course I submit to a paradoxical view of life where chaos/order are integrally the same self creating reality and that the answer which makes the most sense is nonsense... it is beyond rational explanation and it is beyond intuitive feeling, it is an integral entanglement of the two, the evidence of a creator of the created, which always was and is therefore uncreated, the projection of your subjective knowing onto an eternal unknown, the connection and dissolve is beyond thought and beyond feeling, yet it feels like it's the truth, at least i think so.

...Put it another way, the answer is the question, the known is the mystery, random chance creates ordered intention and vice versa, evolution may well be a chaotic and spontaneous thing, chaos spontaneously creates order (they are the same), this makes a paradoxical sense so I like it.

I like the hindu myth (massive paraphrase) god is in a state of divine union, bliss and all that yet he seeks adventure and companionship, one is the loneliest number, so there is a schism where his counterpart (the other) is running away and changes form. God is lost and cannot recognise the new(alien) form but there's some subconscious communication from the other which suggests that they are one, god recognises unity so again the other must transform, this happens ad infinitum creating the myriad forms of the universe. I think we're just lost in space right now finding our counterpart.

Edited May 30, 2011 by The Dude

[CβL]

Human Evolution and Hair Loss

Why did humans lose their hair over time? Human ancestors may have developed sexually before they developed physically and so ended up hairless.

One of the striking features about the human race is its lack of hair. If you compare humans to our closest relative, the chimpanzee, the difference is pretty obvious. Why did we become so much less hairy?

There are a number of theories out there. One is that when we left the trees and headed out to the savannah, having no hair helped keep us cool. Or that we lived a semi-aquatic life for awhile and so lost our hair. Or that we lost our hair to gain protection from parasites.

These are all interesting ideas. But none of them explains how we lost our hair. An intriguing theory that offers an explanation is called neoteny.

Neoteny is just a way to say that an organism has reached sexual maturity before it has reached physical maturity. This sounds strange but can and does happen in nature. And if it happened with our ancestors, it would certainly explain why humans lack fur.

The classic example of neoteny is the mole salamander. Some species of mole salamanders will shift when they are ready to have babies based on what the environment is like.

For example, if the weather is dry and the pond is drying up, a salamander may become sexually mature as a tadpole. When these eggs hatch, the weather will again determine when the next generation is ready to have babies.

Sometimes, though, a species will stay more or less permanently stuck in the immature form. A species of salamander called Axolotl is one such case. At some point in the past, this species of salamander became arrested in the tadpole stage physically. But it still can become sexually mature in this stage even though it is essentially a tadpole.

Some scientists think people may be like the Axolotl. The idea is that at some point in our past, a group of our ancestors became sexually mature before they became physically mature and it stuck. This group of sexually mature juveniles went on to become us.

There aren’t any hard facts to support this idea but there is some intriguing circumstantial evidence. For example, a baby chimpanzee looks remarkably like a human baby. They are both hairless (except on the top of the head) and their skull structures are similar. Also, baby chimpanzees and baby humans have an incredible capacity to learn.

As each species grows, they start to lose these similarities. Chimps get much hairier and their skull structure changes significantly. Chimpanzees also stop learning well as adults whereas humans can keep right on learning into adulthood.

We do seem like chimpanzees that never grew up. Unfortunately there isn’t any easy way to prove this theory—skin and hair just don’t fossilize well. We’ll have to wait for scientists to find the change(s) that keep us from developing hair. From that scientists may be able to tell if the change should have a big effect like neoteny. Or a little effect like hair loss.

http://www.suite101.com/content/why-we-lost-our-hair-a32448

Further evidence for neoteny is hypertrichosis, suggesting many of the genes for rampant hair growth are still intact, and possibly just inactived:

http://rafonda.com/speculation_on_speciation_prin.html

[WoodDragon]

The thing with neoteny is that it is a just genetic mechanism for enabling phenotypic change in characteristics. It is not a reason in itself for the retention of immature features, as it does not operate as as external, environmental pressure.

[Distracted]

The thing with neoteny is that it is a just genetic mechanism for enabling phenotypic change in characteristics. It is not a reason in itself for the retention of immature features, as it does not operate as as external, environmental pressure.

 

Sorry do ask... could you dumb that down for me? Thanks!

[tripsis]

I would read it like this. The genes responsible for neoteny are already present and are just expressing themselves to present an outward appearance of immature features. This means that they can't be the reason for continued immature features, as they are not an external pressure driving evolution.

[WoodDragon]

Basically, what Tripsis said.

Genes are programmed to work both within the space of an organism, and over time during its life. Some work all the time, some alternate between periods of being 'on' and 'off', some are active only in the early part of life, and others are active later in the organism's life.

Neoteny reflects the fact that genes that usually shift an organism from its juvenile phase are not activated, or are disabled. If this happens from a purely random genetic event, or series of events, the results is almost always deleterious because species are adapted to growing and maturing in their environment. Sometimes, however, during changes in the environment a neotenous state can be selected for, if a juvenile stage has advantages in that changed environment. In such cases it it the environment that is the pressure on evolution, and neoteny is merely the process by which the pressure operates.

Take salamanders as an example, as they were referred to above. Usually their tadpoles develop in ephemeral ponds, which means that they risk dying out if the pond dries. Further, they may have a greatly enhanced chance of long-term survival by taking advantage of terrestrial refuges and/or food sources, compared with remaining in an aquatic environment. But if things change, and the terrestrial environment becomes more hostile whilst the aquatic environment that hosts their tadpoles remains constant and undrying, then salamanders that remain as juveniles longer, or that retain their juvenile characteristics (gills, in this case) whilst still proceeding to sexual maturity, have an enhanced rate of survival.

The mechanisms of neoteny are many and varied, and it is important to realise that neoteny refers to the state of retaining juvenile characteristics into sexual maturity, rather than to a specific genetic process. In axlotls the process involves (but is not restricted to) changes in iodine metabolism, and this can be demonstrated by the fact that adding excess iodine to axlotl tadpole's environment can induce the formation of lungs/loss of gills, and thus of a normal terrestrial salamander phase. In domestic animals there are many juvenile behaviours that are retained (such as meowing and owner (= parent) orientation), but these characters remain through different genetic alterations (adding iodine to a cat's diet won't turn it into a wildcat!).

If human hairlessness is related to neoteny, then it is only in the sense that hairlessness is a newborn mammal characteristic, and as such an alteration of the developmental pathway of switching on hair growth might have been a route to respond to an environmental pressure. Without such a pressure, an otherwise hairy species living in equilibrium with its environment would soon succumb to thermal and ultraviolet stress, wounding, and other injuries that are mitigated by the presence of hair, if it suddenly stopped growing hair. Further, it is quite possible for hairlessness to evolve not by co-opting the retention of juvenile characteristics, but by modifying de novo the expression for adult ones. There's a subtle difference, and the latter process is not neoteny, even though it might 'look' like it.

As to using neoteny to cool down just because the environment is hot, one only needs to look at many of the other mammal species in Africa to realise that in the case of humans this doesn't hold water. Even human-sized, or larger, predators retain their fur - the difference is that humans evolved a hunting technique that required them to keep cool (and smart), whilst they tracked their prey over long periods of time to the point of heat/energy exhaustion of the prey. Other predators are pounce/short-dash hunters, and long-term heating leading to heat exhaustion is not as much of an issue for them.

The very large animals of the savanah lost their fur because they have a lower surface area to volume ratio, and thus retain heat so efficiently that they do not need insulation, especially when they have subsurface fat in which to store energy and with which to protect themselves. Mole rats on the other hand are subterranean, where the environmental conditions are very stable, and hence hair is not only unnecessary but an encumbrance.

On the matter of humans being 'aquatic', its important to remember that most human-sized (or less) mammals that are aquatic retain their fur, so that theory doesn't hold. And the webbing between our fingers is no different to the webbing between the digits of many other non-aquatic mammals - it's there to allow our digits to move in many directions without contriction, and not a because it's a remnant of a previous, aquatic life. Wiggle your fingers around a bit and you'll see what I mean, or ask a burns victim what tight skin does for flexibility...

As I said in my first post, currently the best explanation for why humans are hairless, compared with their cousins and ancestors, is that it is an adaptative response to the evolution of persistence hunting on the open plains. In science there are rarely any certainties, so it might not be the actual explanation, but to date I have seen nothing in the evolutionary literature that is superior to this explanation, and many other theories that simply fall over under close scrutiny.

[Here endeth the lecture... ]

[Edit to move a dodgy apostrophy. ]

Edited June 3, 2011 by WoodDragon

[tripsis]

Good explanation Woody, thanks for taking the time to write it up. Posts about biology are always welcome to me.

[Teljkon]

asdasdas

Edited December 19, 2021 by Teljkon

[Rabaelthazar]

This is why I love the Corroboree. You can post a left-of-centre question and get pages of interesting, intelligent feedback from a wide range of viewpoints.

Thanks everyone for contributing.

[mutant]

Awesome thread , thanks for the lecture WD.

I find male shaving of anything but head and face distasteful. Never shaved anything on the rest of my body, don't intend too. I find female hairness unpleasant and turning off, but I have been surprised to not be so much affected with a particular girl I fancied a lot who didn't care enough to shave her legs - but she was very young and all. I don't need the female genitalia to be totally shaved, but it doesn't thrill me to meet an abandoned bush. Armpits and legs I find distasteful though...

I also find shaved head women sexy! Still haven't fulfilled this fantasy.

I have thought about human sexuality and what determines it a lot.

After this conversation, I can safely conclude that all these tastes are culturally determined mostly. One of the main factor co-shaping our sexuality is pornography. I am surprised almost noone seems to conclude all this shits are culturally learnt behaviours.

I thought that the habit of women swallowing/pretending to swallow/having men cumming on their face was such a learnt behaviour, that is a derogatory habit that males learnt by porn - but I consequently learnt that women eating fathers cum while pregnant is beneficial to the fetus!

Edited June 1, 2011 by mutant

[Rabaelthazar]

but I consequently learnt that women eating fathers cum while pregnant is beneficial to the fetus!

 

Is that eating their fathers' cum or the cum of the fathers of their children?

[mutant]

father of their children.

true for some certain first weeks of pregnancy I think

[tripsis]

Can you provide some links where you read that?

[mutant]

Boy I do have to look for that. But I reassure you its not joke.

[Halcyon Daze]

Just for the record, I saw on a discovery channel that loosing our fur is what helped us become the top predators. Not only did we loose our fur but we gained very efficient sweat glands.

The one major significant advantage of this efficient cooling system is that we can run down our prey over many miles and eventually we will win out. I think they called it 'Persistence Hunting' or something like that.

Other animals are limited in how far they can run because they eventually become overheated, slow and fatigued, and this is when we strike. This may have even helped our brains to develop as we started to think and plan ahead, hunt in organized packs and communicate etc.

No other animal has a cooling system like ours and losing our fur is a big part of that.

Also for the record, My dutch milkmaid gf gets really excited by my furry body, and just the sight of her in that state is enough to trigger the full fury of my animal instincts.

Edited June 3, 2011 by Halcyon Daze

[mescalito]

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.

 

Was that the interview with Credo Mutwah,the African Shaman?

He addresses exactly what you are saying....and before y'all jump in and go "Banana's" about this,just think about how far we have come in this life-time alone...the unimaginable has become REALITY!

One that is so real we take it for granted,like life wouldn't work without the "new" technology that we only read and dreamed about in comics.... and if you don't have one of these or one of those,MAN you are so 80's!.....just think about it.

If you for example believe it's plausible about Jesus and His miracles,Immaculate Conception,then why not "Alien" Intervention?...it's just as far fetched....even remote viewing and the sacred rituals of the Amazonians amongst others.Where they stupid? Whacko?

They formed well organised and functioning societies based MOSTLY on these abilities,things we dream about and search for....This is called Shaman Australis no?

From my limited understanding,there was a new start after the "Big Flood" and these creatures were separated by water onto land masses as can be seen by Hairier Mediterraneans,Darker Skinned types with varying hair growth,height etc.,Paler races with varying eye shapes,head shapes etc....the boat thing,well I have my doubts,but it may have been a way of the story-teller to convey what happened before,just skewed over time as language evolved through linguistics,which is not our first nor most evolved form of communication.

These "races" learned to communicate through a language they made,which still stands today(as does our hemi-spherical brain)....y'all talk of DMT the spirit molecule and the Pineal.Ask yourself how that gland lost it's gusto

Darwin obviously asked the same questions,but because it was in the age of writing,published and made "common" sense,then people started to convert or even combine this with Christianity.....weird world.

I've tried to find a clip,but can't track one down about a Tribe that was attacked while the men were hunting,apparently all women were murdered,some children remained and some of the tribesman's nipple's being a sweat gland modified in response and were able to breastfeed.Can someone find this,I saw it years ago on a Doco.

The real question is why are the genitals and arse crack sporting hairdo's?

[WoodDragon]

Mutant is right about the swallowing of semen.

It's a complicated immunological story, but basically repeated exposure to the "human leucocyte antigens" on the male's cells can trigger a suppressive adaptive immune response in the woman.

The gastro-intestinal tract has immune tissue called Peyer's patches that sample the antigens going through the GI system, so that the body can learn friend from foe. Usually things that travel regularly through the gut are related to food, which should be tolerated, so the possible immune responses to many food antigens are toned down after repeated exposure and 'learning to identify' via the Peyer's patch response. If the father's, or potential father's, semen is a regular item through the gut, then it is likely that a tolerance can be acquired, especially at "mucosal" surfaces (mouth, gut, bladder/urethra, vagina).

In such circumstances having a degree of tolerance to the father's HLA profile can make the difference between successful conception/pregnancy, or not. If the mother has an active immune response to the father's HLA type, her mucosal response in the vagine/uterus/Fallopian tubes can wipe out the sperm before they can fertilise her ova, so damping down the mucosal immune response may overcome this problem.

And it is a problem - I'm not sure of the exact percentage (10-20% approximately, I think), but a portion of infertility cases are a result of immune incompatibility between the female and the male's sperm. A similar immune response might also occur between the mother and her embryo, if fertilisation happens to be successful in spite of an active immune response to the father's sperm, because half of her embryo's HLA genes will come from the father.

So if a woman has trouble getting pregnant, or staying pregnant, one possibility that is worth considering is swallowing rather than spitting. It's not a guarantee, but it may help the odds. One of the labs I worked in used to offer a service to infertile couples where we conducted a 'desensitisation' similar to treating allergies to bee venom, except in this case the goal was to damp down the female's immune response to the male's HLA. Instead of using the sperm though, we used white blood cells from the male, processed in the lab so that his HLA proteins could be used to 'immunise' the female (it's easier to get large amounts of white blood cells than to get buckets-ful of sperm!). It's a tricky thing, because desensitising immunisation basically occurs in the same way as standard, sensitising immunisation, but it differs mostly in the amount and repetition of injection of the target proteins. A bit like the gut - the body usually assumes that if it's regularly exposed to an antigen then it might actually be OK to allow, and so eventually turns an otherwise active response down. The exact way in which this occurs isn't completely understood, so it can be hit and miss, but that's off-topic straying...

Anyway, the lab treatment did work for a significant number of couples who had been infertile for years. I suspect that had the treatment been tailored to operate mucosally, via the gut rather than through the peripheral blood stream, it might have worked even better, but there are some clinical issues with deploying purified protein through the stomach.

The upshot though is that if the male is not carrying any STDs, nor has any other obvious contraindicating conditions, a course of swallowing might be just what the doctor ordered to get a pregnancy happening to term!

Edited June 3, 2011 by WoodDragon

[WoodDragon]

The real question is why are the genitals and arse crack sporting hairdo's?

Secondary hair (armpits and genitals) seems to have two functions - to help prevent chaffing, and to help waft pheromone signals from the individual by providing a large, rapidly-evaporating surface area. Don't underestimate the effect of pheromones in humans - they are more important than most people realise, and having a good dispersal system in the context of our evolutionary past was probably quite important in mate selection.

In prehuman women (and indeed, even in modern human women) having a very hairy pubic area may have helped with camouflage of œstrus cycles, which would in turn have helped in luring males to care for her, and any children she may have, in the periods between her fertile days.

As for arse hair, especially in men, I suspect that it might be an anti-chaffing adaptation as well. Women's hips are further apart than men's, so a standard-sized adult female human on the savanah probably wouldn't have chaffing butt-cheek issues, and thus wouldn't need the hair there.

If I recall correctly Karl Kruzelniski once did an experiment where he had his radio listeners test armpit and ungly-bit chaffing, both with and without hair, to actually test the theory... I think that without-hair on average did chaff more, but others here might recall it better than I do.

Heh. Reading back over this thread, I think that maybe I need to get a life.

[tripsis]

That's really interesting to know that not only is what mutant said true, but the process behind it to. Your posts are always high quality Woody.

Interesting that a portion of infertility cases are due to immune incompatibility between the partners.

I have no doubts in my mind that pheremones play a significant role amongst humans. I've been very turned on in the past by the smell alone of particular women before.

[WoodDragon]

Interesting that a portion of infertility cases are due to immune incompatibility between the partners.

Yeah, a lot of people don't appreciate that this is a cause of infertility.

Within the purview of this cause for infertility, there is some actual real 'incompatibility', where a woman's immune system simply won't 'mesh' with the HLA type of the prospective father's, and then there are instances where the woman's immune system has simply fired up the 'wrong' way. In the latter case, which is probably the more common, there is at least the opportunity for resetting, as I described above.