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Memories of the 28th Century

Who Are Modern Humans

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It might simply be that most of the magazine articles that are written about evolutionary anthropology are written by journalists who don’t know much about evolutionary Anthropology, but I still find it annoying to read things like this article about genetic evidence of interbreeding between so-called modern humans and Neanderthals around sixty thousand years ago. The basic information is fine, but it was written with a slant that suggests that there was something strange about people from two groups of humans getting it on. The implication is that the writers of the articles may have the mistaken idea that Neanderthals were not humans, and that simply isn’t true. Most of the humans of today are descended from Neanderthals in addition to being descended from the other predecessors of modern humans. Neanderthals were of the same species as other humans, but they lived in more northerly areas and were adapted to living conditions in those areas. That is not surprising or unusual.

As far back as there were animals that might be called humans, those people were moving around and adapting to different living conditions. Tools that were appropriate for a particular are and that area's plants and animals had to be devised on the spot, and that is something that Neanderthals were very good at.

In addition to Neanderthals there were other races in earlier times, and I mean "race" in the scientific sense. Although they were different races; they interbred whenever they got a chance. While there weren't a lot of people wandering from Europe to East Asia fifty thousand years ago, there were people, or groups of people, who did travel. The people who write articles about this matter often ignore East Asians. Homo Erectus was in East Asia from about 1.7 million years ago, and humans with skulls that are similar to modern East Asian skulls evolved there more than a half million years ago, long before the recent X and Y chromosomes bearers got to that area.

That there were human ancestors in Europe and East Asia more than a half million years ago is not contradictory to the idea that all humans are descended from African ancestors from about 200,000 years ago. The Out of Africa concept is based on analysis of X and Y chromosomes and mitochondrial DNA only; it is not a claim about the entire genome. It is quite possible that a newcomer to an area could introduce a different sex chromosome and that chromosome could completely replace the pre-existing sex chromosome within a few generations. The exact number of generations would depend on the local population, but all human populations were small 200,000 years ago. Because the separation of DNA during meiosis is random it is even possible that only the sex chromosomes would be passed on after the first generation; that is unlikely and mentioned only as an illustration.

If one looks at all of the available evidence , then one will conclude that a combination of the “Out of Africa” and “Multiregional” theories is much more likely than either theory. If the Out of Africa theory were the only correct theory, then there would be no Neanderthals genes in present day humans, because all of the genetic material would have come from African sources within that last 200,000 years. But the similarity of X and Y chromosomes shows that there was emigration from Africa within the last 200,000 years that replaced earlier X and Y chromosomes.

I have not introduced any new ideas here. This is simply an explanation of information that already existed. Unfortunately, news articles about this seldom bother to explain that Out of Africa and Multiregional theories do not contradict each other; they simply help to explain each other.