ivegotyou wrote:
does this mean that americans will look like cherokees in 10'000 years?
The question presupposes all sorts of unlikely things for the next 10 k years.
Technology would have to go back to the stone age- and remain at the stoneage level so the true effect of environmental selection could be felt. There would have to be no immigration and no emmigration. An ofcouse no bio engineering of humans.
The Cherokees themselves were reletively recent invaders. They were descended from Asian migrants who entered North America only about 12thousand years ago and hadnt changed much from their asian ancestors.
Consider skin color.
Africans, New Guineans, and Australian Aborigonies, all have extremely dark skin (and are called "black") as an adaptation to the fierce equatorial sun.
Each of those groups has lived on the equator for over 100 thousand years. Indeed dark skin was probably a legacy of our equatorial pre human ancestors.
In contrast: the Indians of the Amazon jungle (also on the equator) are no darker than the Cherokee of temperate North America.
This is because the Indians of the Amazon have only lived on the equator for about 10 K years.
Further- many amazonian Indians retain the folded eyelids and high cheekbones of their Asian ancestors. Both of these traits are adaptations to life in Ice Age Siberia ( ie to COLD conditions).
So even after ten thousand years indiginous Amazonian peoples are still well adapted to cold weather and show little evidence in their physiques to have ever having lived in the tropics.
So it takes longer than 10 thousand years for humans to change much, and even stoneage people are good at adapting to new environments and thwarting the selective presures of the environment. And ofcourse we are all out of the stoneage anyway.
Even when humans do physically adapt to a local environment they dont necessarily adapt the exact same way as previous occupants of the same locale.
The Neanderthals were physically specialized to life in Ice Age Europe. They were short and stocky and had thick limbs ( to retain body heat).
They were replaced by the anatomically modern Cromagnon people about 35K ago.
These first anatomically modern europeans were long and lanky with long limbs (adapted for dissapating heat in the tropics) much like modern Africans. Indeed they came from Africa by way of western Asia.
Modern Europeans are actually shorter and stockier than thier stone age Cromagnon ancestors. So some enviromental evolution has occured in Europe in the last 35k years.
But Europeans did not "become" neanderthals. They did not evolve the long projecting faces and heavy brow ridges of Neanderthals. They just became slightly shorter, slightly less gracile anatomically modern people.
So even if White and/or African Americans lived in America for 100k years in stoneage isolation there is no reason to think that they would evolve into cherokee Indians.
15 Nov 2010, 8:41 pm
