Posted on 12/26/2002 8:02:36 AM PST by PatrickHenry
The theory that we are all descended from early humans who left Africa about 100,000 years ago has again been called into question.
US researchers sifting through data from the human genome project say they have uncovered evidence in support of a rival theory.
Most scientists agree with the idea that our ancestors first spread out of Africa about 1.8 million years ago, conquering other lands.
What happened next is more controversial.
The prevailing theory is that a second exodus from Africa replaced all of the local populations, such as Europe's Neanderthals.
Some anthropologists, however, advocate the so-called multiregional theory, that not all the local populations were replaced.
They think some of these ancient people interbred with African hominids, contributing to the gene pool of modern humans.
The new evidence, published online in the Proceedings of the National Academy of Sciences, is based on an analysis of data from the human genome project - the effort to map the entire human genetic blueprint.
Blood and bones
Researchers led by Henry Harpending, professor of anthropology at Utah University, studied small differences in human DNA known as single nucleotide polymorphisms.
Studying when these mutations appeared gives a window into the ancient past, allowing scientists to trace the rise and fall of early humans in different parts of the world.
"The new data seem to suggest that early human pioneers moving out of Africa starting 80,000 years ago did not completely replace local populations in the rest of the world," he says. "There is instead some sign of interbreeding."
The study suggests that there was a bottleneck in the human population when ancestors of modern humans colonised Europe about 40,000 years ago.
This is a puzzle because earlier human genetic studies have backed the idea that a rapidly expanding African population spread globally and replaced all local populations.
One possibility is that there was limited interbreeding between humans migrating from Africa and local populations in Europe and elsewhere.
'Open question'
Commenting on the research, Professor Chris Stringer, Head of Human Origins at London's Natural History Museum, said that in the last few years the multiregional model of human evolution had been called into question by new data, much of it genetic, showing our species had a recent African origin.
He told BBC News Online: "Arguments now centre on whether we are recently and entirely Out of Africa, or just mainly so.
"Some replacement models, and some genetic data, suggest no interbreeding at all with archaic peoples outside of Africa, while other replacement models allow limited interbreeding with the locals over the short time scale in which they overlapped.
"This new research suggests there could have been some interbreeding, but as the authors recognise, it could have been limited, and whether it happened at all is still an open question."
When it comes to their profession, yes. This was the stupidest analogy I've ever seen on these threads, and I've seen some really stupid analogies before.
We have no DNA evidence of any non-human species other than Neanderthals.
And, in this situation, we don't need to. Either you didn't read the article, or, more likely, you didn't understand the article. The study was done by comparing different groups of humans across the globe to ascertain when or if humanity spread from Africa. Non-human DNA would have been useless in this study, don't you think?
Wanna bet that he'll top it next month?
When it comes to their profession, yes. This was the stupidest analogy I've ever seen on these threads, and I've seen some really stupid analogies before.
Guess prostitutes do not lie? They are good people? They have morals? You keep showing how ridiculous you are.
We have no DNA evidence of any non-human species other than Neanderthals.-me-
And, in this situation, we don't need to. Either you didn't read the article, or, more likely, you didn't understand the article. The study was done by comparing different groups of humans across the globe to ascertain when or if humanity spread from Africa. Non-human DNA would have been useless in this study, don't you think?
I did read the article and YOU do not think. The article is about whether Homo Sapies arose from other species of hominids. The only DNA ever found from other species of hominids is from Neanderthals and those show that Homoe Sapiens did not descend from Neanderthal. Therefore there is no basis for comparing any DNA to show descent from any other species and the study is just nonsense. In addition, in the short space of some 2000 years of history, there have been dozens of invasions of Europe from as far afield as Mongolia, so there has been a lot of mixing of DNA from the far corners of the globe in that short period. To extrapolate from nothing to nothing with no evidence at all is total deceit and because these people are justifying their taking of government money (my money) with this garbage, constitutes fraud and grand theft. So yes, these people you call scientists are indeed prostitutes and I can see why you are defending prostitutes - they are so much like those you hold in such high esteem.
Secondly, the article is about when humanity spread out from Africa -- whether it was once, or several times. One does not need to compare human and non-human genomes to make this determination. One need only compare extant human populations to weedle out this information. One of these days you'll get a clue as to what you are talking about.
Thanks for the insult. It shows quite well that you cannot refute my statements. It is admittedly not a very gentlemanly concession, but it is a concession nevertheless. Bye.
No one works harder to get onto other posters's "ignore" list or tries to make more hay out of being ignored than The Blue Boy.
Why the sudden animosity towards hookers, anyway? It's not particularly Christ-like, is it? Or are you harboring a personal grudge for some reason?
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