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Author Topic: Fair Hair?  (Read 2520 times)

Offline 5nutjob

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Fair Hair?
« on: 23/11/2010 20:36:26 »
Ever noticed the gradual darkening of children's hair through to adulthood? - I've a theory;- The surface area to volume ratio of a body decreases with size. Therefore, a small body will lose heat much quicker than a large one. This was obviously a huge problem for our ancestors, to those who perhaps migrated to northern Europe from Africa.
 
Infant mortality must've been horrendous, but eventually via evolutionary adaptation, thinner lips, fine blonde hair (and the like) appeared. I propose;- children are fairest when they are young, is a simple consequence for the need to conserve body heat when it is most critical, as light hair 'reflects' heat back to the head far better than dark hair - as their bodies grew, this insulative measure was required to a lesser and lesser degree; hence, the mirrored evolutionary response.  [:I]

ps;- even polar-bear cubs are whiter than their parents.

pps;- Eskimo's are dark skinned 'cause they've no fur, and need to screen ice reflected ultra-violet radiation by means of pigmentation - thus another adaptation has occurred with these people ..... monumental magnitude body fat.  [:I]
« Last Edit: 23/11/2010 20:55:18 by 5nutjob »


 

Offline QuantumClue

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Fair Hair?
« Reply #1 on: 23/11/2010 22:35:24 »
Hair goes darker because the body produces more melanin as time goes by.

Case closed :)
 

Offline maffsolo

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Fair Hair?
« Reply #2 on: 23/11/2010 22:48:07 »
Hair goes darker because the body produces more melanin as time goes by.

Case closed :)

What happens when to too much time goes by???
 

Offline Bored chemist

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Fair Hair?
« Reply #3 on: 24/11/2010 06:59:41 »
Radiative heat loss from people is small because their temperature is not very different from their surroundings.
Hair is a pretty good insulator whatever its colour.
Also, people invented clothing. Until recently the cliché image of a young child was wearing a hat.
 

Offline Karen W.

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Fair Hair?
« Reply #4 on: 24/11/2010 07:32:48 »
But what happens when the hair eventually turns gray?
 

Offline 5nutjob

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Fair Hair?
« Reply #5 on: 24/11/2010 21:40:35 »
But what happens when the hair eventually turns gray?

Easy ...... evolution pulls the plugs when you've had sufficient time to have babies. [:I]
« Last Edit: 24/11/2010 21:51:32 by 5nutjob »
 

Offline CliffordK

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Fair Hair?
« Reply #6 on: 03/12/2010 09:55:00 »
Hmmm....  Interesting.

Any evidence that Blond hair reflects more IR heat back to the body?
I would think the opposite would be true that dark hair [O8)] would absorb more heat.

Everything that I see indicates that lighter complexion is connected with lighter hair colors.  And, that the lighter complexion favors absorbing Vitamin-D.  And, children growing strong bones.  It is possible that the reds and blonds were just a side-effect of the lighter complexion (which, of course, might predispose one to certain skin cancers after the child rearing years).

See the Wikipedia Notes:
http://en.wikipedia.org/wiki/Blond#Evolution_of_blond_hair

Of course, that doesn't mean that there isn't space for new theories.

But, I would note that human hair is not a great insulator.  And I would have to question why body hair (which also isn't the greatest insulator) comes on so late in life.

In fact, there were some notes about the difference between Neanderthals and Homo Sapiens (that lived concurrently in Europe around 30,000 years ago).  The theory was that the Neanderthals grew body insulation (hair and fat) to protect them from winter weather, while the Homo Sapiens did better with making clothing.  So...  they could be equally warm in the winter with heavy clothing, but more agile in the summer by just leaving the coat home.

http://web.me.com/duncancaldwell/Site/Neanderthals.html
http://asaa-persimmonpress.com/doc/neanderthals_final_form.pdf
http://asaa-persimmonpress.com/doc/insulation_after_thoughts.pdf

I would point out that human infants would be essentially helpless in northern climates (especially during the ice age) without blankets and clothing. 

Even a 2 yr old toddler doesn't have enough natural insulation to venture out in sub-zero weather without a bundle of clothing.  It is likely that all northern humans had developed a symbiotic relationship with their clothing that insulation from hair played a secondary role.

However, a few patches of skin poking out through the blankets would be vital for generating Vitamin-D.

Perhaps the reason that beards and body hair appear late is that the face is vital for children absorbing Vitamin-D.  However, as adults, the bone growth diminishes, and the need for high levels of Vitamin-D becomes secondary to the need for insulation and protection.  Furthermore, the adult men would naturally be spending more time outdoors.
 

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Fair Hair?
« Reply #6 on: 03/12/2010 09:55:00 »

 

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