Evolution: Human Hair, glitch?

[arkain101]

Some thoughts crossed my mind recently when I was watching 'lord of the rings' dvd of all things. I was noticing how all the characters had long hair, and usually long beards.

 

This I realised was part of the theme and culture but, I started thinking what other mamals and creatures have hair that does not stop growing.

 

If we evolved form monkeys why did we take on a mutation gene that caused our hair to grow and grow and grow?

 

As young humonoids before we were masters with cutting tools was this characteristic of our hair growing forever the cause of our doom? If one did not find a way to cut their hair it would surely affect there ability to survive as a dumb half monkey human creature.

 

I havn't done much research on this but I started to think that it was most unusual for evolution theory.

 

Human facial hair and scalp hair can grow at a rate of about 1cm a MONTH, or 0.44 mm per day.

 

It is something I would like to look into to see how evolutionary theory can explain this. Is there a connection between other humonoid species and hair growths? Is it an original trait for us to grow hair forever in comparison to the animal kindom?

 

Is there any other traits homosapians have that are considerably unusual..

 

howstufworks hair: Each hair on your body grows from its own individual hair follicle. Inside the follicle, new hair cells form at the root of the hair shaft. As the cells form, they push older cells out of the follicle. As they are pushed out, the cells die and become the hair we see.

 

A follicle will produce new cells for a certain period of time depending on where it is located on your body. This period is called the growth phase. Then it will stop for a period of time (the rest phase), and then restart the growth phase again.

 

When the hair follicle enters the rest phase, the hair shaft breaks, so the existing hair falls out and a new hair takes its place. Therefore, the length of time that the hair is able to spend growing during the growth phase controls the maximum length of the hair.

 

The cells that make the hairs on your arms are programmed to stop growing every couple of months, so the hair on your arms stays short. The hair follicles on your head, on the other hand, are programmed to let hair grow for years at a time, so the hair can grow very long.

 

Animals that shed have hair follicles that synchronize their rest phase so that all of the follicles enter the rest phase at once. This way, all of the hair falls out at one time. A dog that sheds will lose its hair in large clumps. Many animals can also switch the coloring agent in the hair follicle on and off -- so in the summer, the hair is pigmented brown with melanin (see How Sunburns and Sun Tans Work to learn about melanin), but in the winter it is not pigmented, leaving the hair white.

[jungjedi]

Some thoughts crossed my mind recently when I was watching 'lord of the rings' dvd of all things. I was noticing how all the characters had long hair, and usually long beards.

 

This I realised was part of the theme and culture but, I started thinking what other mamals and creatures have hair that does not stop growing.

 

If we evolved form monkeys why did we take on a mutation gene that caused our hair to grow and grow and grow?

 

As young humonoids before we were masters with cutting tools was this characteristic of our hair growing forever the cause of our doom? If one did not find a way to cut their hair it would surely affect there ability to survive as a dumb half monkey human creature.

 

I havn't done much research on this but I started to think that it was most unusual for evolution theory.

 

Human facial hair and scalp hair can grow at a rate of about 1cm a year, or 0.44 mm per day.

 

It is something I would like to look into to see how evolutionary theory can explain this. Is there a connection between other humonoid species and hair growths? Is it an original trait for us to grow hair forever in comparison to the animal kindom?

 

Is there any other traits homosapians have that are considerably unusual..

 

you asked if we evolved from monkeys.i believe the genitic code goes all the way back to the dinasours

[HappytheStripper]

you asked if we evolved from monkeys.i believe the genitic code goes all the way back to the dinasours

 

Wow.. if you wanna go further than that .. there is always the single cell.. why stop at the dinosaurs..

 

Ashley

[CraigD]

It is something I would like to look into to see how evolutionary theory can explain this.

I think this is a deep question to which evolutionary biology can at present provide speculation at best. Some of that speculation may be correct, but scientifically deciding which ones is a daunting challenge.

Is there a connection between other humonoid species and hair growths? Is it an original trait for us to grow hair forever in comparison to the animal kindom?

Though I’ve seen several primates with long head and face hair – for example, the various kinds of tamarins, a small monkey popular in my local zoo (the Smithsonian National Zoo), none of them appear to approach humans in the maximum length of their head hair. Though I’ve not systematically studied hair length in the animal kingdom, the only animal I’ve personally encountered with hair as long as a human (I’ve known women with hair longer than 2.2 meters!) is the domestic horse (I’ve seen a show horse with tail hair longer than 1.8 meters – it had to be kept “set” to avoid dragging on the ground, except, of course, in shows).

Is there any other traits homosapians have that are considerably unusual..

There are many – my first exposure to a long yet incomplete list was Desmond Morris’s The Naked Ape.

 

Among the best known speculative explanations for human hair’s length is part of the aquatic ape hypothesis. Under this hypothesis, one or more proto-human species spent a lot of time wading and swimming in deep water. Long hair served to enhance infants’ ability to hang on to their moms, eventually selecting for females with long, easy to grab hair, the offspring of females without it being more likely to be lost in the surf, gobbled up as their moms fled from sharks, etc. The aquatic hypothesis also explains male-female hair dimorphism, the tendency for human females to have longer, thicker hair than males, a dimorphism that’s not common in the animal kingdom (Lions, for example, where males have long manes, females do not).

 

In the absence of a definitive explanation of the extraordinary maximum length of human hair, I’ll throw out my own “macro-explanation”: humans evolved long hair because it is pretty. Individuals with long, thick hair signal good health to potential mates, so have a reproductive advantage, causing selection for the genes responsible for it. Our instinctive attraction to “good-hair people” remains powerful even today (Happy’s avatar is an example).

[arkain101]

:hihi:

 

:)

 

 

 

I think this is a deep question to which evolutionary biology can at present provide speculation at best. Some of that speculation may be correct, but scientifically deciding which ones is a daunting challenge.

 

Thankyou craigD. I would agree that it is quite a mysterious puzzle.

 

 

In the absence of a definitive explanation of the extraordinary maximum length of human hair, I’ll throw out my own “macro-explanation”: humans evolved long hair because it is pretty. Individuals with long, thick hair signal good health to potential mates, so have a reproductive advantage, causing selection for the genes responsible for it. Our instinctive attraction to “good-hair people” remains powerful even today (Happy’s avatar is an example).

 

Interesting. However, when the cave people took on a wild animal the people who had their hair getting in their eyes and tripping over and getting caught in trees would not show a very good signal of survivability. The pretty factor is interesting. Though, in my naive response, judging purely on mindless surviving, long hair may show a coming of age, but eventually might of been a sign also that it was nearing the time of their death. This I say that repetition might have shown that long hair was a bad thing (before the intelligence to do anything about it) and when fellow members of the tribe/heard had very long hair they may of had to stay away from hunts, or be considered more likely to die. This I would look at to consider like, I would not want to breed with a women who had cancer and was about to die, and although this is harshly speculating, super long hair might of been similar in concept.

[arkain101]

There are very few if any caveman representations with long beards and hair. They always look like they have monkey fur. This I think is a poorly accurate representation.

 

They probably learned to cut it on rocks and stuff, but the origin of this long hairness is still important to consider. Evolution concept is something I still do not sit with that well.

 

Here are some examples of what cavement might have looked like. :) :hihi:

 

 

 

 

[Boerseun]

A very interesting question, indeed.

 

And, also, very interesting to note that it's only our head and facial hair that don't stop - all the other hair on our bodies grow to their set length, and then stop, like any other animal.

 

I've my own theory about this - but before I go on, have you ever noticed how strange someone looks if they had a beard and a mullet for ever, and the next day you see them, they're clean-shaved with short hair? You almost don't recognise them, and it's like making friends with a completely new person! That's the whole story...

 

When our ancestors were tree climbers, eyesight became considerably more important than the sense of smell. Thus, the eyes moved to facilitate a forward-looking very effective stereoscopic view, intruding on the nasal cleft, which shrunk to make way for the eyeballs. When they eventually got our of the trees and adopted a bipedal gait, they primarily depended on their eyes for hunting - and as the brain expanded forward, the nasal cleft had less and less space to play with, becoming ever less important. It could almost be said that our sense of smell is near to becoming a vestigal sense, almost like a sloth's ears. Compared with the rest of the animal kingdom, we suck when it comes to smelling stuff. We are primarily visual-input driven.

 

Now here's my theory:

 

Regarding the above, humans are not specialised in anything. We're not particularly good runners or climbers or burrowers or hunters. Yet, we were able to pull down mammoths many times our size, through co-operative hunting in well-prepared, organized teams. Now consider for a second that humans have the biggest number of individual muscles in their face of any animal, able to move them in many ways unique to the species. There is no animal with such a mobile face as humans. The reason for this, of course, is communication. It is to instantly communicate identity, which is very important when you're hunting in a pack. Other hunters hunt together and determine identity via smell, which we cannot do. So, we have these mobile faces, and by just glancing at someone, you can instantly tell their identity, mood, etc. We take it for granted that humans have such different looking faces, but its a big oddity in Nature. Think about it for a second.

 

So how does this plug in with hair? I believe the fact that human facial and head hair don't stop growing, also adds to visual identity perception, increasing the distance from which you can be identified. Seeing as humans have developed the ability to cut their hair when it gets too long, either with rocks or whatever, it means that hair lenght was no detriment to survival. Rather, it could have been sexually selected (the guy with the thickest beard is the 'lion' of the tribe, etc.) or the way every individual differently solves the problem of long locks (one will plait it, one will roll it up, another will just let it hang, etc.) makes identification from a distance much easier.

 

I mean think about it - someone that you've known for ages with long hair, looks utterly strange (from even close up) after having cut their hair.

 

Interesting topic, nonetheless.

[jungjedi]

Wow.. if you wanna go further than that .. there is always the single cell.. why stop at the dinosaurs..

 

Ashley

 

cause dinasours are way cooler than ameabas.and ive seen conjectures on the discovry channel that say they may have had featherlike hair

[Boerseun]

cause dinasours are way cooler than ameabas.and ive seen conjectures on the discovry channel that say they may have had featherlike hair

Hair is exclusively a mammalian invention. No other animal has hair.

[maikeru]

In the absence of a definitive explanation of the extraordinary maximum length of human hair, I’ll throw out my own “macro-explanation”: humans evolved long hair because it is pretty. Individuals with long, thick hair signal good health to potential mates, so have a reproductive advantage, causing selection for the genes responsible for it. Our instinctive attraction to “good-hair people” remains powerful even today (Happy’s avatar is an example).

 

That seems like a major possibility. Would it be much like the peacock's tail? Another example to show off the quality of one's genes by how they manage and can afford to "waste" energy on expensive features like muscles, fat, big brains, coloring, etc.? Hair requires a lot of energy to grow and some maintenance, so, as you mentioned, it would be taken as a sign of health, youth, and vigor. I've read that during times of famine or malnutrition, hair growth often slows drastically or hair can even stop growing and fall out during stressful times, maybe to help conserve the body's energy.

 

Men's facial hair, much like muscle and body build (the V-shaped torso and small hips), seems to signal how much testosterone they produce. More testosterone encourages more and thick facial hair. Women's hair would signal how healthy they are, similar to how they are judged by hips and overall body shape (the hourglass).

[jungjedi]

Hair is exclusively a mammalian invention. No other animal has hair.

 

yep.dinasours may have even been warmblooded

[arkain101]

A friend of mine shared an article he found related to this topic.

 

Don't call it fur!

 

After combing the scientific literature, researchers conclude head hair and fur aren't the same

 

By Jim Dryden

 

 

Dec. 27, 2004 -- Mammals have fur over most of their bodies, but at some point during evolution, we humans lost that fur covering. Researchers at Washington University School of Medicine in St. Louis argue that hair on the head is somehow different from fur because fur stops growing when it reaches a certain length, but our head hair continues to grow. To drive home their argument, they ask in a recent article in the journal Evolutionary Anthropology, "Have you ever seen a chimpanzee getting a haircut?"

 

Neufeld AH, Conroy GD. Human head hair is not fur. Evolutionary Anthropology, vol. 13:3, p. 89, June 2004.

Don't call it fur!

[InfiniteNow]

Article Quote: To drive home their argument, they ask in a recent article in the journal Evolutionary Anthropology, "Have you ever seen a chimpanzee getting a haircut?"

 

Actually, yes...

 

[skuzie]

Hair is a byproduct of fish scales thinning out and loosing their original purpose in water for the purpose of heat capturing. The general rule of thumb is the colder it is the longer the hair 'or fur' will get, look at various animal species like dogs or bears. Our 'native' environment where we along side with monkeys evolved is of course Africa, which is warm. When we relatively recently migrated northward we encountered a more colder environment thus spurring larger hair growth.

[ErlyRisa]

I haven't read the whole thread ... but to me the answer is obvious.

 

Humans : From monkeys....

 

start losing hair, after they invent Fire.

they lose even more when they live in vast open spaces (african svanagh) -(africans today are almost hairless, even today (climate/proportion of sweat, would be a strong factor))

 

now humans move to other areas , which have different climates...

 

the Hair gene now has no idea what is necessary -- in grease it decided for a thin blanket, to hold sweat away from the skin in the ocean breeze... in the middle of Europe it decided that a minimal banket was necessary, especially so when Heavy clothing was used.

 

...so in effect the human genome has decided to evolve to allow for mutiple climatic circumstances that the individual may reside in.... the major question is what trigger the need for a variable length/blanket of hair.... it was the Fire.. wwhen the first monkeys were stressing thier bodies from very high heat to normal climating surrounding, the genome accomodated this constant sporadity.

 

--My cat is actually losing the hair near it's back - where It loves to sit right next to the space heater... and that's not even a single generative change....in order for the offsripng of my cat to be able to accomodate the sudden fluctuations of heat/cold they would need to be able to 'grow' and 'shed' a blanket.

 

Hairy People = semi windy warm climates (clothes are unnecessary, a little warmth from a thin blanket helps keep warm air at the skin in colder conditions, yet on hot days doubles as a semi effective radiator of body heat) -note, not a good scenario for high radiant heat climates, eg. South America, Africa.

 

Stubble Hariy People = high radiant heat from sun. -no good for winter conditions.

 

Hairless People = cloth wearers... the Europeans, the Chinese., note that the colder the climate (Russia) then some blanketing around the lower body is usually still called for, but because of cloth wearing on the heading, especially in the very cold climates, Head/Facial hair grows even less.

 

 

anyway... --you could write a book... it's all pretty darn logical, and am surprised that we would not already come to this conclusion.

[billg]

I like the idea of humans losing the hair on account of being too hot with lots of hair... not only from the climate (which I don't think could have been particularly different from other African primates) but also, I would suggest, because increased brain size; the brain in humans supposedly accounts for 20 percent of our energy demand while weighing only 2 percent, and it seems likely it generates a lot of extra body heat.

 

The argument that fire had anything to do with it seems pretty unlikely to me. Also maybe your cat shouldn't sit so close to the heater...

[ErlyRisa]

I think Fire has everything to do with it...

 

just like we use stemcells, and we 'Train' the cells into the body part we desire... the outershell (the skin and hair), re-trained itself to cope with the varied sporadic change.... it's only option was to use material as it could and grow hair as physically quickly as possible, but at the same time look for a happy medium(centre not material)