Posted on 08/16/2006 11:38:54 AM PDT by PatrickHenry
One of the fastest-evolving pieces of DNA in the human genome is a gene linked to brain development, according to findings by an international team of researchers published in the Aug. 17 issue of the journal Nature.
In a computer-based search for pieces of DNA that have undergone the most change since the ancestors of humans and chimps diverged, "Human Accelerated Region 1" or HAR1, was a clear standout, said lead author Katie Pollard, assistant professor at the UC Davis Genome Center and the Department of Statistics.
"It's evolving incredibly rapidly," Pollard said. "It's really an extreme case."
As a postdoctoral researcher in the lab of David Haussler at UC Santa Cruz, Pollard first scanned the chimpanzee genome for stretches of DNA that were highly similar between chimpanzees, mice and rats. Then she compared those regions between chimpanzees and humans, looking for the DNA that, presumably, makes a big difference between other animals and ourselves.
HAR1 has only two changes in its 118 letters of DNA code between chimpanzees and chickens. But in the roughly five million years since we shared an ancestor with the chimpanzees, 18 of the 118 letters that make up HAR1 in the human genome have changed.
Experiments led by Sofie Salama at UC Santa Cruz showed that HAR1 is part of two overlapping genes, named HAR1F and HAR1R. Evidence suggests that neither gene produces a protein, but the RNA produced by the HAR1 sequence probably has its own function. Most of the other genes identified by the study also fall outside protein-coding regions, Pollard said.
Structurally, the HAR1 RNA appears to form a stable structure made up of a series of helices. The shapes of human and chimpanzee HAR1 RNA molecules are significantly different, the researchers found.
RNA is usually thought of as an intermediate step in translating DNA into protein. But scientists have begun to realize that some pieces of RNA can have their own direct effects, especially in controlling other genes.
The proteins of humans and chimps are very similar to each other, but are put together in different ways, Pollard said. Differences in how, when and where genes are turned on likely give rise to many of the physical differences between humans and other primates.
Researchers at UC Santa Cruz, the University of Brussels, Belgium and University Claude Bernard in Lyon, France, showed that HAR1F is active during a critical stage in development of the cerebral cortex, a much more complicated structure in humans than in apes and monkeys. The researchers found HAR1F RNA associated with a protein called reelin in the cortex of embryos early in development. The same pattern of expression is found in both humans and rhesus monkeys, but since the human HAR1F has a unique structure, it may act in a slightly different way. Those differences may explain some of the differences between a human and chimp brain.
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The chimpanzee genome was published in Nature in 2005, showing that the DNA sequences of humans and chimps are more than 98 percent identical. The current work was funded by the Howard Hughes Medical Institute, the U.S. National Institutes of Health and other agencies.
Are you telling me you don't like your fried chimp? How about some broiled chimp then.
Well, duhhhh. What a shock.
Brilliant debating tactic! Here's another one to chew on: The principal proponent of a policy of eugenics, the basis for the Nazi's "social engineering" program , was Darwin's cousin.
Yes. You get the poor communication of these press release sensationalist headlines and articles.
The answer would be: One of the fastest-evolving pieces of DNA in the human genome is a gene linked to brain development.
You are correct in your stickling for detail and accuracy.
What do you mean by "jump."
But when it comes to figuring out where the apes come from, 's 'nuther question you don't wish to talk about.
There is no evidence that humans and monkeys are related. There is a 3% difference between the DNA of disparate humans. We are no more related to monkeys than we are to dogs, horses and crocodiles.
Jump.....YOU KNOW.... The gap where things are not connected.
I still don't know what you mean by jump. How does the term relate to evolution?
29+ Evidences for Macroevolution. Yes, macro-evolution.
Ichneumon's legendary post 52. More evidence than you can handle.
Post 661: Ichneumon's stunning post on transitionals.
Plagiarized Errors and Molecular Genetics. Anatomic similarities are confirmed by DNA similarities and copying errors.
Evidence of Evolutionary Transitions. There really is evidence out there.
Transitional Vertebrate Fossils FAQ. Yes, transitional fossils exist.
8,000+ papers on vertabrate evolution. National Academy of Sciences.
Fossil whale with legs. Land animal to whale transitional fossil.
NEW Newly found species fills evolutionary gap between fish and land animals. Another transitional fossil.
[Dead link?] Feathered Dinosaurs.
Archaeopteryx. Reptile-to-bird transitional fossil.
Archaeopteryx: FAQS . A true transitional fossil
All About Archaeopteryx . Human Ancestors.
The Evidence for Human Evolution. For those who claim there isn't any evidence.
Comparison of all Hominid skulls.
NEW Man-chimp evolution. Ichneumon's post 29.
What is your source for this?
"There has never been a proved jump at the Order Level."
Chimps and humans belong to the same order.
False. DNA in humans varies by about 0.1% - any two random humans will have 99.9% of their DNA in common.
In Africa, humans do eat chimps. It's called "bush meat" and is though to have contibuted to the beginning of the AIDS epidemic. Not from eating the meat, from butchering the animals.
I don't know quit what you mean by that statement. Obviously evolution occurs at the level of populations, leading from time to time to the emergence of new species. So "jumps" only can occur at the species level (or below). New higher taxa (genera, families, orders, etc) are only recognized in retrospect.
For example when the first primate evolved it was, at that time, highly similar in the vast majority of respects to contemporaneous insectivores. It's only in retrospect that what were then piddling little details, such as the morphology at the base of the skull, can be recognized as distinctive of an entire Order. If taxonomists had been alive at the time there's no way in the world they would have classified the earliest primates as a separate Order. It was only over time, and many speciation events, that primates acquired the full suite of distinctive characteristics warranting the Ordinal designation.
And anyway, humans and chimps are in the same Order.
Evolution of a brain isn't necessary for survival....hence...."bird brain".
Would if we "tweeted" instead of talked?
Makes sense as chimps are'nt human and there is no relation between the two.
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