Note: this topic is from . Thanks Pharmboy. Just adding, not pinging.
Posted on 08/26/2002 1:22:49 PM PDT by Pharmboy
WASHINGTON (Reuters) - A gene that separates humans from the apes and all other animals seems to have disappeared from humans up to three million years ago, just before they first stood upright, researchers said on Monday.
Most animals have the gene but people do not -- and it may be somehow involved in the expansion of the brain, the international team of researchers said.
The gene controls production of a sialic acid -- a kind of sugar -- called Neu5Gc, the researchers write in an advance online issue of the Proceedings of the National Academy of Sciences ( news - web sites).
"This mutation occurred after our last common ancestor with bonobos (pygmy chimpanzees) and chimpanzees, and before the origin of present-day humans," they wrote. Neanderthal skeletons, the oldest early humans from who DNA has been obtained, also lack the sugar.
"It happens to be first known genetic difference between humans and chimpanzees where there is a major outcome," Ajit Varki of the University of California San Diego, who led the research, said in a telephone interview. "We are exploring the consequences of this."
Varki said the role of the gene is not fully understood.
"The gene itself is involved in changing the surfaces of all cells in the body," he said. "The surface of all cells in the body is covered with sugars. This one is missing only in humans."
It may help influence how viruses and bacteria infect cells, and with how cancer cells interact, Varki said. "There are some clues that it might have something to do with brain plasticity," he added.
Humans and chimps share more than 98 percent of their DNA, so a few genes must make a big difference. Chimps and humans split from a common ancestor 6 million to 7 million years ago.
The collaboration of some of the top experts in various fields, ranging from anthropology to the genetic differences between people and apes, determined that this gene disappeared from humans between 2.5 million and 3 million years ago.
"It happened after the time that our ancestors stood upright, when their hands and so on were like ours, but their brains are still same size as that of chimpanzees," Varki said.
"That just tells you the timing is appropriate for the possibility that this may have something to do with brain expansion."
The team included anthropologist Meave Leakey of the Leakey Foundation in Nairobi, Kenya, an expert in early humans, and Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who helped study the first Neanderthal DNA.
Earlier this month Paabo's team reported that the had found mutations in a gene called FOXP2 that seems to be involved in the face and jaw movements necessary for speech. A relatively small change makes the human version of the gene different from the version found in apes, the researchers found.
Trying to pull a fast one there Jenny! The statement was in regards to your reference to the rabbit being 33% different from man. Actually the fugu genes have helped us identify some 1,000 human genes which other research (including the genome project) had not found. Regardless though, the point is that gene comparisons are insufficient to determine much at all. The other factors within the 'junk' DNA are much more important and we are just beginning to learn about them.
(Don’t Fear) The Reaper
Aqualung
Folsom Prison Blues
Seriously though, if you are a fan of Roy Orbison, I recommend his Black and White DVD.
That's the point, it is not. The complexity of an organism in no way depends on the number of genes. Neither do its abilities. If the fugu's genes were not quite alike to a human's we would not have been able to use the genome of the fugu fish to discover genes which had not been found by the smartest scientists we have or by the best equipment we have when we did the genome project. Sure, man is very different from the fugu fish, but the difference is not in the genes. Man's intelligence as opposed to that of monkeys is not in the genes either, it is in the expression of certain genes. It is the other DNA, the one we do not understand comletely, the DNA evolutionists call junk, that allows us to make 100,000 proteins with only 30,000 genes. It is that DNA, not the genes that makes us what we are.
Essential cell division 'zipper' anchors to so-called junk DNA
Egad! Junk is not "junk". Who'da thought? A "histone code"? But of course, I approach this announcement with an open mind; I study it carefully; and I critically consider it. Further, since it is just a hypothesis, I don't expect to see it in schoolbooks.
Note: this topic is from . Thanks Pharmboy. Just adding, not pinging.
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