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The oldest "human" we know of came from Africa. How are we sure that the ancestors of that oldest human we know did not come from Europe or Asia and immigrated to Africa? And, how are we sure that these ancestors did not leave some siblings behind in Asia or Europe and their offspring stayed in Asia and Europe?
It's tough to prove that something didn't happen. All we can do is theorize about what did happen based on the available evidence.
What are the species? South Asians and Europeans only have a negible amount of Denisovan and Neanderthal DNA.The vast majority of SNPs that define non Africans are through natural selection.
1-4 percent of the genome of non-Africans is made up of the Neanderthal contribution. 3-5 percent of Melanesians' genome is from Denisovans. Melanesian/Australians carry both. That isn't an insignificant amount. For comparison, your great-great-great grandfather contributed 6 percent of your genes.
Africans also have mixed with an archaic human species whose identity is still unknown. It appears that introgression from other human species is the norm, not the exception. Neanderthals and Denisovans may have mixed with others like homo erectus and we may have picked up some of those genes indirectly. There is some physical continuity from east Asian homo erectus to modern east Asians, which suggests that this is the case.
First of all it's a theory.
Second, it's a puzzle with not all the pieces in place...yet.
Are you suggesting something different than evolution?
I believe in God or a higher power and we are a part of a plan that is beyond our understanding. But no, I did not evolve from apes. Absolutely ridiculous notion.
Some preacher figured out the world was 6,000 or so years old from biblical genealogy. He was wrong.
60,000 years is about 3,000 generations and that is plenty of time for humans or anything else to adopt to different and or changing environmental conditions by natural selection.
1-4 percent of the genome of non-Africans is made up of the Neanderthal contribution. 3-5 percent of Melanesians' genome is from Denisovans. Melanesian/Australians carry both. That isn't an insignificant amount. For comparison, your great-great-great grandfather contributed 6 percent of your genes.
Africans also have mixed with an archaic human species whose identity is still unknown. It appears that introgression from other human species is the norm, not the exception. Neanderthals and Denisovans may have mixed with others like homo erectus and we may have picked up some of those genes indirectly. There is some physical continuity from east Asian homo erectus to modern east Asians, which suggests that this is the case.
Why don't they share uniparental markers with these other hominids?
I believe in God or a higher power and we are a part of a plan that is beyond our understanding. But no, I did not evolve from apes. Absolutely ridiculous notion.
Why don't they share uniparental markers with these other hominids?
Those who carried the archaic Y DNA and mitochondrial DNA died off. Further research on the Neanderthal genome has shown that there was a high degree of genetic incompatibility with the human genome. Male Neanderthal/human hybrids were partially or completely sterile. And for whatever reasons, Neanderthal mtDNA didn't survive to present day (that we know of).
Although as gene sequencing becomes cheaper and more widespread, we might discover that there are people who still carry these markers. Just a few years ago, it was found that a small number of Africans possess a Y chromosome that is over 330 thousand years old, which is before humans even existed as a distinct species. This discovery pushed back the date of our most recent common male ancestor significantly.
Those who carried the archaic Y DNA and mitochondrial DNA died off. Further research on the Neanderthal genome has shown that there was a high degree of genetic incompatibility with the human genome. Male Neanderthal/human hybrids were partially or completely sterile. And for whatever reasons, Neanderthal mtDNA didn't survive to present day (that we know of).
Although as gene sequencing becomes cheaper and more widespread, we might discover that there are people who still carry these markers. Just a few years ago, it was found that a small number of Africans possess a Y chromosome that is over 330 thousand years old, which is before humans even existed as a distinct species. This discovery pushed back the date of our most recent common male ancestor significantly.
I think that archaic Y DNA finding was retracted after it didn't account for the mutation rate. It's just an earlier variant of haplogroup E.
I'm well aware of retrogression that took place in homo sapiens, but it's dishonest to suggest that non Africans diverged entirely through admixture. Selective pressures took place. Don't forget that Africans are still more closely related to non Africans than Denisovans/Neanderthals are.
I think that archaic Y DNA finding was retracted after it didn't account for the mutation rate. It's just an earlier variant of haplogroup E.
I'm well aware of retrogression that took place in homo sapiens, but it's dishonest to suggest that non Africans diverged entirely through admixture. Selective pressures took place. Don't forget that Africans are still more closely related to non Africans than Denisovans/Neanderthals are.
Why do you feel the need to continually make this point? I never suggested otherwise.
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