Posted on 04/23/2005 8:30:41 PM PDT by Lessismore
MILWAUKEE, WISCONSIN--About 1200 researchers gathered near the shores of Lake Michigan here from 5 to 9 April to discuss early Englishmen, the birth of modern humans, and Stone Age weapons.
In the past 15 years, a flood of genetic data has helped propel the Out of Africa theory into the leading explanation of modern human origins. DNA from mitochondria (mtDNA), the Y chromosome, and ancient humans each suggest that the ancestors of all living people arose in Africa some time after 200,000 years ago, swept out of their homeland, and replaced archaic humans around the globe without mixing with them. But at a genetics symposium, two independent groups presented data from the X chromosome hinting that modern humans interbred with other human species: The teams found possible traces of archaic hominids in our genes. "Just as the Y and mtDNA data seemed to have settled it, the new data revive the question [of interbreeding]," says Stanford University's Joanna Mountain, co-organizer of the symposium. "The controversy is not settled." Geneticists Makoto Shimada and Jody Hey of Rutgers University in Piscataway, New Jersey, presented an intriguing haplotype--a set of genetic mutations inherited together--that appears to have ancient roots in Asia rather than Africa. Shimada sequenced a 10.1-kilobase noncoding region in 659 individuals from around the world. Overall, the genetic variations were most frequent in Africa, just as expected if our ancestors were a subset of ancient Africans who migrated out of that continent. But one rare variant, appropriately named haplotype X, appeared in nine individuals from Europe to Oceania but was entirely absent in Africa. Shimada estimated that the haplotype arose 1 million years ago, long before the modern human exodus from Africa. "Haplotype X is difficult to explain by the recent African origins model," says Shimada. "It's very old, it's rare, and it is widespread outside of Africa."
In independent work, geneticist Michael Hammer of the University of Arizona in Tucson offered a similar example. Hammer and postdoc Dan Garrigan identified a 2-million-year-old haplotype in the RRM2P4 region of the X chromosome that is common in East Asia but vanishingly rare in Africa. Their work, published 2 months ago in Molecular Biology and Evolution, raises the possibility that the haplotype arose in very ancient Asian populations, presumably of Homo erectus, an ancient human once found across Asia. "This is what you'd expect if you had introgression" between modern humans and H. erectus, Hammer said.
But at this point several other explanations are possible. Hey of Rutgers acknowledges, for example, that haplotype X may be present in Africa but was missed by spotty sampling in that continent. "Simply observing those [examples] is not sufficient to rule out one model or another," cautions Mountain. "What you need is 10 or 50 loci--one or two is not sufficient." Hammer, for one, thinks that these preliminary data do "speak to some archaic admixture. The few [loci] we've done so far are so suggestive that it gives me great excitement to continue sequencing more loci."
No---Down's Syndrome individuals have an extra chromosome, so instead of 46 like you and me, they have the odd number of 47. This produces the typical syndrome, but there is a broad range of its manifestations.
The chinese knew this already....the homo erectus branches in China were peopled with Shovel toothed specimens just like themselves.....
But once you've had a taste of non-Sapiens, there's no place to draw the line. In for a dime ...
It is generally accepted that both Neanderthals and Homo sapiens evolved from earlier "archaic" Homo sapiens, but the classification of Neanderthals depends on when in the timeline these modern humans are considered a separate species from the "archaic" forms.
So, it may in theory be the case that they were similar enough from a genomic standpoint that we haven't been able to distinguish the admixture. But more likely not! I'm quite skeptical of the idea myself. If so, where did all the distinctive Neanderthal features go? Stated differently, how could all the progeny bear such a remarkably indistinguishable resemblance to other Homo sapiens?
And the differences between Homo erectus and Homo sapiens makes the differences with Neanderthal seem downright trivial. Brain capacity alone: Homo erectus had 75% that of Homo sapiens. So, if they mated, where did all the retard hybrids go?? :)
But once you've had a taste of non-Sapiens, there's no place to draw the line.Well put.
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
DNA from mitochondria (mtDNA), the Y chromosome, and ancient humans each suggest that the ancestors of all living people arose in Africa some time after 200,000 years ago, swept out of their homeland, and replaced archaic humans around the globe without mixing with them.
I guess "no evidence" is euphemism for "no evidence I find persuasive"......
If this is the same "haplotype X" than it has been found in Africa. I'm assuming haplotype X is referring to a mtDNA sequence.
"A maximum parsimony tree of 21 complete mitochondrial DNA (mtDNA) sequences belonging to haplogroup X and the survey of the haplogroup-associated polymorphisms in 13,589 mtDNAs from Eurasia and Africa revealed that haplogroup X is subdivided into two major branches, here defined as "X1" and "X2." The first is restricted to the populations of North and East Africa and the Near East, whereas X2 encompasses all X mtDNAs from Europe, western and Central Asia,Siberia, and the great majority of the Near East, as well as some North African samples. Subhaplogroup X1 diversity indicates an early coalescence time, whereas X2 has apparently undergone a more recent population expansion in Eurasia, most likely around or after the last glacial maximum."
http://www.usenet.com/newsgroups/sci.anthropology.paleo/msg05159.html
Don't forget that the odds against a sperm cell are a hundred million to one in the swim competition. Overall, the chances of any particular individual surviving to reproduce are about a billion to one.
Just in case anyone tries to make that case that most mutations are detrimental.
Throwback is a prescientific term, with not current meaning. There are many kinds of mutation, and chromosome copy errors are one. In plants, chromosome mutations are common and frequently lead to new species. This is rare, in animals, but it does happen.
All known human chromosome mutations are considered detrimental.
That's a cool graphic.
There was an explosion of human 'branches' at this time and then again during/at the Last Global Maximum, 25-18,000 years ago. (Oppenheimer)
There are to types of the 'shovel' teeth, Sindont and Sundont(sp.). The Sindont is a branch off the Sundont family and are the Northern Asians and are characterized by flatter faces, the peculiar eye lid and lighter skin. My hunch is that this occurred in an isolated group in the north during the LGM.
Now, I saw a program about the 'Hobbits' on Flores and they were speculating that they are Homo-Erectus however, they found 80k year old shell necklaces at the site. Homo-Erectus wasn't suppose to have the brain capacity for making necklaces.
Also, I've read that the brain size of Cro-Magnon Man was larger than modern humans. And, someone mentioned on another thread that Homo-Erectus and Neanderthal had larger brains too but, I suspect this is incorrect.
There are quite a number of groups who are willing to test your DNA for a fee, but the National Geographic program is the most reasonably priced that I've seen.
However, they aren't testing the maternal mitochondrial DNA in males, so if you are a male and want that done, you need to go elsewhere.
This program tests the (maternal female-to-female-to female, etc.) mitochondrial DNA in females, and the Y-chromosome (paternal male-to-male-to-male, etc.) DNA in males.
Females don't have Y-chromosome DNA but males do have mitochondrial DNA, which they get from their mother, not their father.
I don't dispute the 1.75 million year date (the oldest estimates of Homo erectus migration out of Africa is 1.8 million BC). I do doubt the 2.25 million year date, only because China is a marked distance from Africa and if Homo erectus had so expanded its range that early one would expect that it would be more readily apparent. However, I have no problem with the idea in the abstract. The Chinese are notorious for 'unsubstantiable' archeological claims..
As for the Flores 'hobbits' if they are what they appear to be from what little I know of them (a dwarf species typical of island fauna) then it seems they could very well be a pygmy erectus. Since the isolated population would've obviously experienced significant genetic change in any event, that may just as well include greater intelligence. That being said, I have no objection to the concept of Homo erectus necklace ability either.
PS. Cutest dwarf species of all: pygmy mammoth!
I don't think children with Down's syndrome could survive in the wild, even high functioning ones.
They don't have the survival instincts that animals have.
Thank you! Occasionally, somebody says something sensible in this "out of africa" nonsense.
I went to the Bradshaw Foundation homepage and found a link to the temples of Malta..
Older than the Egyptians..
And then they simply disappeared..
The site also provides an explanation for the "cart tracks" of Malta....
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