A question about human evolution.

[danot]

Thing is it doesn't take 100,000 years for evolution to take effect. A white person going to a hot climate can change colouration within days. Interestingly Blacks don't because their colouring is natural, evolutionary wise that is.

 

Cross continent interbreeding would also have an effect..as it does now.

Granted, White skin can darken in a matter of days, whereas black skin is naturally black and remains black throughout life. But I'm not talking about any one individual here, I'm talking about an entire race of people who over a period of 100,000 years are exposed to climate conditions that are the extreme opposite to those which were responsible for their current appearance.

[0742Sheff]

It is thought that man first came from Africa. I do not know what climate Africa had 150,000 years ago but if it was warm, like it is today, you would expect that early humans would have evolved with darker skin. I think this shows that what we already class as a white person has already evolved in to a different colour.

 

I therefor think if the scenario arose in the OP, people could indeed change colour. The other physical aspects might not go the same way though. Height, build and muscle structure/density could all be governed by the living conditions we found ourselves in.

[danot]

That is not evolution. The darker colouring will not be passed on to the next generation. In your example the tan/sunburn is an acquired trait. The child of a sunburnt man and a sunburnt women would not produced a red peeling child. Their appearance may change in response to the environment but their genetics will not have. (hopefully)

 

On a side note I was wondering that if these two groups, that are seperated physically with very different environments, could have speciated within 100,000 years. I assume there is no interbreeding with these two populations are they are clearly in different parts of the world and are "uninterrupted by technology".

Yes. They are unaware of each other.

[skinz]

Yes. They are unaware of each other.

 

In which case I'm not now sure of the question.

 

Are you now suggesting or hypothesizing that we change the existing singular evolution period as we know it and replace it with x2 evolutionary periods, entirely separate? One cradle in Africa and another in Russia lets say.

 

Just trying to get the foundations of where you're coming from..

[danot]

In which case I'm not now sure of the question.

 

Are you now suggesting or hypothesizing that we change the existing singular evolution period as we know it and replace it with x2 evolutionary periods, entirely separate? One cradle in Africa and another in Russia lets say.

 

Just trying to get the foundations of where you're coming from..

That more or less sums up what I'm asking.

[skinz]

That more or less sums up what I'm asking.

 

As an answer I'm not only trying to get my head around "if" but "how" that could happen..using existing evolution as a template. We have to use something as a template, and using the present one it just seems inconceivable if not impossible, and if we use those both sentiments it's a hard question to answer...if at all.

[danot]

As an answer I'm not only trying to get my head around "if" but "how" that could happen..using existing evolution as a template. We have to use something as a template, and using the present one it just seems inconceivable if not impossible, and if we use those both sentiments it's a hard question to answer...if at all.

Well the scenario is only hypothetical, I wasn't claiming it could happen, I only set the scenario so I could pose the question. I know the scenario sounds a little far fetched but the question I asked isn't. The question was based on the existing evolutionary template.

[skinz]

Well the scenario is only hypothetical, I wasn't claiming it could happen, I only set the scenario so I could pose the question. I know the scenario sounds a little far fetched but the question I asked isn't. The question was based on the existing evolutionary template.

 

Lets forget the North for the time being...scenario: Man evolves in Africa...he's White. Are you suggesting we come up with a hypothesis as to why he's White when the present template says he should be Black? It can't be done unless there's a precedent we can work from.

[plekhanov]

My question is about the evolutionary process that allegedly is responsible for there being various groups of people of differing physical appearance, commonly known as races.

 

I understand and accept the theory of what caused the various physical attributes which gives each race of people their particular look of ethnicity, but if it is simply the melanin in the body reacting to extremes of climate conditions, what would happen if for instance, the world has we know it ended tomorrow due to massive tidal waves of biblical proportions which resulted in 99% of humanity being wiped out.

 

Now only two groups of people exist, a group of only white's in an extremely hot, dry and humid climate, and a group of only black's in an extremely cold,damp and green climate. If both groups lived this way for the next 100,000 years unaltered and uninterrupted by technology or modern day science, (as the world as we know it no longer exists remember) would the white group eventually evolve and develop the physical appearance of black people (and vice versa ) due to the extremes of climate which they have been accustomed to?

First off I don't think there is such as thing as "the physical appearance of black people" beyond skin colour, 'black is a vague term which encompasses a vast, enormously varied range of humanity.

 

Looking at skin colour alone (which is the only factor uniting 'black people') the white group in the hot and sunny area would certainly have a much darker skin colour after 100,000 years (which iirc is longer than the time it took for all of humanity once it left Africa to evolve).

 

It is far from guaranteed that the black group in the cold area would end up "white" as in Northern European in skin colour though. If you think about it most peoples in temperate to cold climates such as Eskimos, the Japanese, far south Americans, Mongolians, Siberians... are not "white". So far as I'm aware the best thinking about how 'whiteness' evolved, is that it was an adaptation to the extremely poor diet endured by those living in northern western europe during the recent iceage, this meant they evolved next to no melanin to get as much Vitamin B12 as possible. As such you'd expect the 2nd groups skin colour to lighten a great deal but not to become 'white'.

[barleycorn]

Stand to be corrected but isn't their/our genetics Black? From an evolutionary perspective that is?

 

IIRC if we trace our ancestry back back to around the time we diverged from our common ancestor with chimpanzees we had light skin covered by dark. You think about it this makes sense as there would be no need for dark skin if you're covered in hair. As we lost our hair our skins darkened through the mutation of various alleles. This provided protection from the increased exposure to sunlight and drove the selection process to those of darker skins.

As to when light skins developed it was not until after the migration into northern, colder climates with less intense sunlight. In these conditions lighter skin tones would not be selected against and indeed have advantages over darker skin tones.

 

To answer the OP, yes if isolated long enough and deprived of various technological advances whites (to use the term loosely) could evolve darker skin tones and blacks lighter skin tones. The selective pressure would certainly be there.

 

jb

 

ETA: It is of course also possible that wither/or both of the two groups exposed to such diametrically opposed conditions may not adapt at all and die out.