Skin color may be an adaptation to the environment/climate, but what about the USA? In this country, the climate does not change much from one state to the next. Yet, children still end up looking like their parents. I wonder how long it takes for genetics to take a back seat and for adaptation to take over? Kind of a scientific question. For example, a girl born to African-American parents in Minnesota will still be black and a boy born to Caucasian parents in Arizona will still be white. You see?
Tracy
Oh boy,…first off, let me get something out of the way: this is a question of
microevolution, not
macroevolution, which even the strictest anti-evolutionist usually concedes
So the reason for that is that the child will continue to be black or brown or whatever, since, even though there is no reason to have that skin color in a north american temperate zone, there’s also no ‘selective pressure’ not to be. That is, as long as it doesn’t confer a disadvantage in breeding, so the modern synthesis of evolution holds, the trait will continue in the genome.
So, since a ‘black’ child in Minnesota will still be able to reproduce (as his or her parents did), and his or her genes are for the ‘black’ phenotype (appearance) and assuming he/she intermarries with a ‘black’ woman or man of course they’re children are going to be black.
No one one here is saying that skin color
is not genetic. Of course it is. Your misunderstanding may be in how environment influences genetic transmission of traits.
So hypothetically, over time, whatever color people are or were, lived in an environment where there was a lot of sun. It would follow that tan skin would confer an advantage (less burning, thus less possibility for infections from blisters-- remember this may have been long ago when we were dirtier folks without much soap and washing, and maybe eve less skin cancer) so ostensibly people with darker skin (from random mutations) would ‘outbreed’ those who did not have darker skin. Over time, more and more of the population would become darker. This is all a very rough outline of microevolution, but that’s that story.
So now, to answer your question! The short answer is, never. One will continue to be born ‘black’ to ‘black’ parents as long as it’s not a disadvantage in reproduction (which I can’t see how it would be), unless one intermarries of course, which is a change in genotype, or unless one mutates (albinism for example), which is also a change in genotype.
Don’t get too hung up on this stuff…
-Teddy Ruxpin
