Yes, God's punishment to Cain
Posted on 03/06/2002 7:38:41 PM PST by ValerieUSA
A new piece of evidence—one sure to prove controversial—has been flung into the human origins debate.
A study published March 7 in Nature presents genetic evidence that humans left Africa in at least three waves of migration. It suggests that modern humans (Homo sapiens) interbred with archaic humans (Homo erectus and Neandertals) who had migrated earlier from Africa, rather than displacing them.
Ancient Origins
In the human origins debate, which has been highly charged for at least 15 years, there is a consensus among scientists that Homo erectus, the precursor to modern humans, originated in Africa and expanded to Eurasia beginning around 1.7 million years ago.
Beyond that, opinions diverge.
There are two main points in contention. The first is whether modern humans evolved solely in Africa and then spread outward, or evolved concurrently in several places around the world.
The second area of controversy is whether modern humans completely replaced archaic forms of humans, or whether the process was one of assimilation, with interbreeding between the two groups.
"There are regions of the world, like the Middle East and Portugal, where some fossils look as if they could have been some kind of mix between archaic and modern people," said Rebecca Cann, a geneticist at the University of Hawaii.
"The question is," she said, "if there was mixing, did some archaic genetic lineages enter the modern human gene pool? If there was mixing and yet we have no evidence of those genes—as is indicated from the mitochondrial DNA and y chromosome data—why not?"
Alan Templeton, a geneticist at Washington University in St. Louis who headed the study reported in Nature, has concluded that yes, there was interbreeding between the different groups. "We are all genetically intertwined into a single long-term evolutionary lineage," he said.
To reach his conclusion, Templeton performed a statistical analysis of 11 different haplotype trees. A haplotype is a block of DNA containing gene variations that researchers believe are passed as a unit to successive generations. By comparing genetic differences in haplotypes of populations, researchers hope to track human evolution.
Templeton also concluded that modern humans left Africa in several waves—the first about 1.7 million years ago, another between 800,000 and 400,000 years ago, and a third between 150,000 and 80,000 years ago.
Alison S. Brooks, a paleoanthropologist at George Washington University, is more cautious about Templeton's conclusions. "Archaeological evidence supports multiple dispersals out of Africa," she said. "The question has always been whether these waves are dead ends. Did all of these people die? Templeton says not really, that every wave bred at least a little bit with those in Eurasia.
"This has not been the majority viewpoint of geneticists up to this point," said Brooks.
Dueling Theories
The fossil record shows that about 100,000 years ago, several species of hominids populated Earth.
Homo sapiens could be found in Africa and the Middle East; Homo erectus, as typified by Java Man and Peking Man, occupied Southeast Asia and China; and Neandertals roamed across Europe.
By about 25,000 years ago, the only hominid species that remained was Homo sapiens. Scientists have conducted a considerable amount of both genetic and archaeological research in an effort to understand how this outcome occurred.
....More at link......
The Neandertal EnigmaFrayer's own reading of the record reveals a number of overlooked traits that clearly and specifically link the Neandertals to the Cro-Magnons. One such trait is the shape of the opening of the nerve canal in the lower jaw, a spot where dentists often give a pain-blocking injection. In many Neandertal, the upper portion of the opening is covered by a broad bony ridge, a curious feature also carried by a significant number of Cro-Magnons. But none of the alleged 'ancestors of us all' fossils from Africa have it, and it is extremely rare in modern people outside Europe." [pp 126-127]
by James Shreeve
I thinks this explains democrats.
They are throw backs.
Only 7 more posts to go!
Man is not an animal species (I know, I know, it's 'debatable')...
Yes, God's punishment to Cain
"The headline itself is confusing. It assumes there is more than one human species."
Yes, that's one of the problematic underlying issues I was getting at. Anthropologists of different schools will define "human" differently depending on their philosophical perspective. Some models of human nature recognize a qualitative difference between human intelligence and animal psychology, others view these as a continuum so that physiological similarities become the defining characteristic of "species". It's difficult to resolve the type of issue the article raises without addressing such underlying issues.
I knew that if they kept casting about that they would eventually find another reason for the need for affirmative action programs.
Great. I turn 40 next month.
Okay, 251.
I'd seen a Liger on Leno one time. The zoo / animal guy said the, uh, liaison happened while the animals were in captivity, and added that the Liger is sterile. I assumed that meant, always. (':
for when I have more time to read
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