Coloured skin

[mr EaZy]

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Why is it that Papua New guineans have the darkest skins out, when the country with the highest recorded temp (Libya at about 56 Deg C) has only lightly coloured inhabitants? Anybody?

[Zarathustra]

The Tasmanian Aboriginals which were wiped out by the English had darker skin than the mainland aboriginals yet Tas. is colder - strange yet true

[malkin86]

It's probably more complicated than hot temperatures = dark skin.

Maybe the Libyans are only recently indigenous, like Causican Australians?

[Zarathustra]

Sunlight and skin colour don't have a direct relationships anyway - it's sexual selection, so if light/dark skin is found to be more attractive it will dominate.

[TheKing]

Uh its to do with UV penetration.

People with darker skin usually absorb/create less of the (?) vitamine (can't remember the letter), less skin problems e.g cancers.

just because a place is colder doesn't mean that it doesnt receive alot of sunlight. Heat does not have a direct effect on skin colour

[TheKing]

i think it might be vitamin D
and that overproduction/deprivation of that has a direct link with some health problem...
i'm very vauge cause i just remember it from somewhere ages ago...

edit: it is vitamin D and the diseases associated with it are rickets and osteomalacia.
Darker skinned people usually synthesis less of it than lighter skinned people. therefore areas of high UV exposure should theoretically have darker
people

[TheKing]

hoped i helped....
and didn't make a fool out of myself

[aloquacious]

i think it might be vitamin D
and that overproduction/deprivation of that has a direct link with some health problem...
i'm very vauge cause i just remember it from somewhere ages ago...

edit: it is vitamin D and the diseases associated with it are rickets and osteomalacia.
Darker skinned people usually synthesis less of it than lighter skinned people. therefore areas of high UV exposure should theoretically have darker
people

ur right, it is uv from the sun which makes the body form vit D, then this reacts with melanin, producing a really nice dark colour ... also happens in hair i think... which is y caucasians have such a high rate of skin cancers n melanomas compared to dark skin n asians etc... cuz their melanin reacts in a big chunk as a melanoma instead of reacting slowly as a dark skin colour etc... well... thats what i think neways... could b wrong...

i want a tan

[Zarathustra]

My point is that just because there are advantages to having light skin (less melanin) in a low UV environment and darker skin in a high UV environment doesn't mean that it happens.

It would be advantageous for the individual and the species if lots of things were different.

The way this is passed on is through Sexual selection as the environment in no way changes the genotype. Obviously in a UV intensive environment people will tan more but this is not the question being asked here

If a person becomes really tanned and their children do for 100 generations, the last descendant would have the same skin colur (in the same environment) as the first generation.

What changes the genotype is the way mates are selected. If a prospective mate had rickets they would still be able to reproduce - but unlikely to be able to out-compete their non-ricket ridden brethren. As change in skin colur has been from dark--->light the other direction needn't be considered.

If for some random reason light skinned people were favoured in a sunny environment or dark skinned people in an aphotic environment; that would be how the descendants would be. Just because it would be better to have a certain attribute doesn't mean that organisms magically acquire it - on the whole they do but there are many exceptions.

[mr EaZy]

Originally posted by Zarathustra
Sunlight and skin colour don't have a direct relationships anyway - it's sexual selection, so if light/dark skin is found to be more attractive it will dominate.

Soooooooooo,,, let me get this straight, your saying that the people in Africa, Australia, south AMerica were originally attracted to the colour black???



I DON"T BUY IT!!!

[mr EaZy]

LOOOOOOOOOOOK mate!!!!!!

Zarathustra
Sunlight is related to UV. Sexual attraction can't explain all the traits we see around us. It has to do with how a feature helps us to survive!!!

Some mates can detect whether the partner is suitable (genetically through hormones), but the basis is on genetic variation only, not through looks

[mr EaZy]

As for the Papua New Guniea vs Libya stuff, we should look at a few factorss: their lifestyle, their relative postions on the equator, What terrain is in each landscape. Think LAtterally dudes


AS for malkin86, your thinkin good, but the Libyans nvr migrated from anywhere, i don't think. It was a land occupied by various cultures : Carthage, Rome, Arabia, Morocco, Egypt, and Spain. They, like the phoenicians are a v. ancient people in the M.East, yet, they are not Black, as we would expect from a hot environment.

YOur UV approach was good, but know that Regions near the poles do get a lot of UV, evn before the ozone hole crisis. But eskimos and russians near Vladivostok and other regions in the north contain white inhabitants.

The south pole receives more UV than the entire equatorial region!!, (but the ice reflects this all into space, hence the land is cold there). Our Aussie scientists don't complain about any skin disorders or irritation. UV might be a factor, but always look at the lifestyle of the people in the region. I think this holds the key to the answer.

[mr EaZy]

Originally posted by TheKing
hoped i helped....
and didn't make a fool out of myself

Well hope again KING!

Who said anything about Vitamin D!!!!!!!!
I check it up to be sure, ur obviously talkn about vitamin K. Vit D is obtained from Fish and Milk.

And only place useful replies and no :

Please.........

[abdo]

Originally Posted by mr EaZy

Soooooooooo,,, let me get this straight, your saying that the people in Africa, Australia, south AMerica were originally attracted to the colour black???



I DON"T BUY IT!!!

umm i don't get what you're saying. i for one am attracted to blacks... well thats not the point though.

Zarathustra's argument is that the amount of uv and darkness of the skin in a population is not directly a cause and effect relationship, if you exclude tanedness as being black.

your skin colour at the time when you were born is determined like any other (or most) attributes you have at birth, natural selection. the direct cause and effect relationship is the particles' (the ones that make up you) position and velocity at any moment of time in this universe, and the subsequent colisions to form you.

if there exist a tribe of people who were attracted to white skin partners and they are living in say the place with a high uv, this tribe would not survive long. since the relatively black skined people survives the sun but does not pass on their gene as they are ugly, and the relatively white skined people does not survive the sun and hence they do not pass on the genes as well. but there are exceptions to this, therefore the process of extinction will take a couple of generations.

therefore it is in my opinion that Zarathustra's argument is not a very strong one (although it is possible), since most likely a group of people of this type would not fair very well in a harsh environment for a long period of time (i.e. a million years). then by the theory of logical reasoning: this people survived, data suggests humans and their ancestors survived for a long time (i.e. if god did not create them in 2000 bc), therefore this people must be the one's who out of luck (i.e. apparently random particle collisions) produced offsprings that are suited to their long term environment by some how having a fetish for blacks while living in africa or whatever. one thing to make clear though, most people seem to falsely think that we are created with a fetish to mate with the strong or the healthy... this is obviously a post hoc fallacy if you know what i mean.

my view is that the people must have migrated from other places where there are differing uv ratings lol... in the ice-age or through some miraculous voyage through the sea by the god's command (apparently this is only possible at around 2000 bc according to civilization III )

[kerry]

the darker pigments of the skin absorb more heat than their white counter parts, but it also loses the heat more rapidly.

If their skin was fair, they would slowly absorb the heat, and even in the shade, their temperatures would be fiery. So their skin is darker as it allows them to dissipate the heat more rapidly.