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Scientists sort the chimps from the men
Science ^ | 11 April 2002 | Helen Phillips

Posted on 04/11/2002 3:37:12 PM PDT by Ahban

The World's No.1 Science & Technology News Service

Scientists sort the chimps from the men

19:00 11 April 02

NewScientist.com news service

A team of molecular biologists have taken a step towards defining what makes us human. It is not so much our differing gene sequences that distinguish us from our primate cousins, but how active those genes are, the team has discovered.

Chimp and human genomes vary by only 1.3 per cent and only a tiny fraction of this actually affects genes. The new research shows how variation in the amount of product of a gene may be as significant to our recent evolution as structural changes.

The greatest changes in gene expression have been in the brain, say the researchers, perhaps explaining why human mental capabilities have evolved so rapidly.

"This is the first open door to understanding how humans became humans and chimps became chimps," says Wolfgang Enard, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, the study's first author.

Hidden changes

"Expression patterns are certainly the key to the differences between chimps and humans," says Chris Stringer of the Natural History Museum in London. "And these changes have been hidden up to now."

But Walter Messier, director of Evolutionary Genomics, Denver, Colorado told New Scientist: "It's sometimes difficult to devise an adequate control when you do expression pattern work. Let's face it, expression patterns can change after one has had lunch, for example. But it is a very valuable approach."

Evolutionary Genomics is trying to identify differences between chimp and human gene sequences, for example in relation to HIV susceptibility.

Five-fold changes

The new analysis compares gene expression patterns in blood cells, liver and brain tissue from chimps and humans, and also orangutans and monkeys for reference. The researchers used a molecular tool called a DNA chip to detect the products of up to 12,000 active genes.

The greatest variations in gene expression patterns were found in the brain. The researchers estimate that there have been more than five times the number of changes in human brains than chimp brains since their evolutionary lines diverged.

This may explain how humans have developed such unique mental capabilities as language, culture and planning, the researchers say. But changes in gene expression must in the end originate from DNA changes and the researchers do not yet know which groups of genes are responsible.

Disease genes

So far only two genetic differences have been biochemically characterised, one affecting cell surface structure and one that may affect hair structure.

Identifying which genes are responsible could help us to learn more about the genetic basis of diseases, says Enard, if we can correlate gene expression patterns with differences in susceptibility to cancer, Alzheimer's or AIDS.

Finally, Enard cautions: "The question of what makes us human can be answered in so many different ways. Never will molecular biology tell us everything."

Journal reference: Science (vol 296, p 340)

Helen Phillips

This story is from NewScientist.com's news service - for more exclusive news and expert analysis every week subscribe to New Scientist print edition.


TOPICS: Miscellaneous; News/Current Events; Philosophy
KEYWORDS: brain; chimpanzee; creation; crevolist; evolution; godsgravesglyphs; humanevolution
So what controls how active genes are? Is there some other control device besides genes that we are missing? How and to what extent does that unkown device "evolve"?

How do human brains go through five times the changes of chimp brains in the same amount of time, even though we have over double the life span?

These are the questions. I doubt we will get definitive answers, but the speculating is kinda fun!

1 posted on 04/11/2002 3:37:12 PM PDT by Ahban
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To: Ahban
“We have broken the code that interprets just 5% of the total amount of information contained in DNA. Even that 5% presents countless mysteries of how that information is manipulated and altered within the human body. It is not like reading a recipe book and baking a cake like Richard Dawkins would have us believe. This “recipe book” is more like 5,000 stacks of books in a huge pile. It is written in a language that we do not understand and we do not have the slightest idea what parts of this pile of “junk” information is used for what. But it is not as simple as that really. Even if we did know what part of the pile was appropriate we do not know at what times that information is turned on and off or how it is otherwise regulated. “
2 posted on 04/11/2002 3:51:53 PM PDT by Heartlander
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To: Ahban
An attempt to link to a similar thread.
3 posted on 04/11/2002 3:57:22 PM PDT by RightWhale
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To: Ahban
So what controls how active genes are? Is there some other control device besides genes that we are missing? How and to what extent does that unkown device "evolve"?

I agree genetic scientist may have been missing something fundamental. Perhaps nucleic DNA may just provide the basic framework of what we are to be.

Perhaps mitochondrial DNA plays a large role in development than suspected.

4 posted on 04/11/2002 4:06:47 PM PDT by Pontiac
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To: Ahban
How do human brains go through five times the changes of chimp brains in the same amount of time, even though we have over double the life span?

No, I think the article says the genes that affect the brain mutated 5 times as much in humans as did chimps' brains' genes since we split off from each other.

5 posted on 04/11/2002 4:13:56 PM PDT by jennyp
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To: Pontiac
genetic scientist may have been missing something fundamental.

I, too, have had this feeling for a few days. Perhaps they have the cart before the horse. They may be going down a dead-end alley.

6 posted on 04/11/2002 4:15:43 PM PDT by RightWhale
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To: crevo_list
Bump.
7 posted on 04/11/2002 4:21:54 PM PDT by Junior
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To: RightWhale
They may be going down a dead-end alley.

Even a trip down a dead end alley is progress. Once you get to the end you go back to the beginning knowing that you went the wrong way.

8 posted on 04/11/2002 4:42:38 PM PDT by Pontiac
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To: jennyp
No, I think the article says the genes that affect the brain mutated 5 times as much in humans as did chimps' brains' genes since we split off from each other.

What the article says is that the genes for the brains of chimps and humans are basically the same. What has occurred is that the way in which those genes are interpreted has changed 5 times fasted in humans as in chimps.

The greatest variations in gene expression patterns were found in the brain. The researchers estimate that there have been more than five times the number of changes in human brains than chimp brains since their evolutionary lines diverged.

9 posted on 04/11/2002 4:51:48 PM PDT by Pontiac
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Comment #10 Removed by Moderator

To: Pontiac
I have used an analogy of a diskette and a computer. A Comodore Amiga disk is useless in a PC. In other words, to get a baby T-Rex you not only need the genes of the T-Rex, but a momma T-Rex to bath the eggs in the right hormones (and Pheromones after laying).

With mammals, this is more critical. The mothers body and how she "reads" the DNA is just as important as what the DNA says. This is analogous to the diskette. How the computer reads those bits and bytes is just as important as what they say.

11 posted on 04/11/2002 6:19:35 PM PDT by Ahban
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To: Heartlander ; jennyp ; RightWhale
My #11 is to you as well.
12 posted on 04/11/2002 6:20:52 PM PDT by Ahban
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To: Ahban
I agree, but I would think the older Apple computers are more analogous.

All from the same maker - they become obsolete – and the software is not compatible.

13 posted on 04/11/2002 6:29:45 PM PDT by Heartlander
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To: RightWhale
That similiar thread had some good stuff in it. I will post what I think are the key paragraphs from it here...

The comparative data suggest that during the evolutionary process, humans somehow altered the process of gene expression in their brains, accumulating expression differences at least five times faster than chimpanzees and distancing themselves from their nearest cousin. A similar trend appeared when the scientists examined differences in brain protein levels.

To determine if the differences between humans and chimps were indeed more than expected between such closely related species, the researchers also analyzed gene and protein expression in two mouse species that are about as genetically different from to each other as humans are to chimps. They found fewer differences in gene expression levels among the mice, further suggesting that the human-chimp discrepancy marks a special evolutionary process

Whatever could they mean by 'special evolutionary process'? Didn't they have a hard time explaning how known mutation rates for both species could have produced the differences already observed between the two? How much bigger is this problem now?

14 posted on 04/11/2002 6:30:34 PM PDT by Ahban
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To: Heartlander
As a creationist, I concur that you have refined the analogy with that 'all from the same maker' bit.

I also think that this study is a point in favor of special creation of humans. See my #14 where a quote from the other story about this study highlights this. They are evolutionists so they call it "special evolution". I guess that is what they call evolution that they have no other explanation for, but count on them to scream 'its not science' every time we say the evidence points to special creation.

15 posted on 04/11/2002 6:36:20 PM PDT by Ahban
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To: Ahban
This has been a growing puzzle ever since the 1980s, when scientists first started looking into the genomes of different organisms and were shocked to discover that a fruit fly, for instance, has many of the same genes as a human. In fact, all living things share the same genes. Mice share 85-90 percent of their genes with us, cows 80 percent, fruit flies 61 percent and bananas 50 percent. How do these common genes make such vastly different organisms on the one hand and, on the other, why isn't the chimp more like us, with an ability to think, talk and create?

When we dare to look at the big picture and use scientific deductive reasoning, Intelligent Design is a very logical conclusion. We like to pretend that we have more knowledge than we actually have or even understand.

To use deductive reasoning to determine that there is no intelligence behind our very own intelligence should make Dawkins laugh. Instead the selfish gene mocks the god that he claims to be…

16 posted on 04/11/2002 6:51:12 PM PDT by Heartlander
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To: seamole
Thanks for indexing it to the lists. I do think it belongs in those lists, but I have never indexed before.
17 posted on 04/11/2002 6:52:52 PM PDT by Ahban
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To: Ahban
The Challenge
18 posted on 04/11/2002 7:08:22 PM PDT by Heartlander
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To: Ahban
How much bigger is this problem now?

The problem might be getting bigger the more is known. They are drowning in data already, and who has the time to look across disciplines? The Middle East solution might be simpler.

19 posted on 04/11/2002 7:25:22 PM PDT by RightWhale
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To: Heartlander
All evo-crevos should take "The Challenge". Good site.
20 posted on 04/11/2002 8:26:36 PM PDT by Ahban
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To: Ahban
Before I call it a night I wanted to get a link to this old but relevant thread up...

Descent of Man Theory: Disproved by Molecular Biology

http://www.FreeRepublic.com/forum/a3b47d7b94f92.htm

Whatever "evolutionary changes" occured in the brains of the human line, humans themselves have a remarkable lack of genetic diversity. IMHO the best interpretation of the evidence presented in the above thread (articles and posts) is that the earliest man appeared 50K ago or less.

21 posted on 04/11/2002 8:45:57 PM PDT by Ahban
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To: Ahban
Whatever could they mean by 'special evolutionary process'? Didn't they have a hard time explaning how known mutation rates for both species could have produced the differences already observed between the two? How much bigger is this problem now?

No, comparing the DNA trees is based on silent mutations. These reveal the mutation rates, because they're not getting filtered out by selection.

22 posted on 04/12/2002 12:42:11 AM PDT by jennyp
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To: jennyp
Ummm. Let's see. I thought the silent mutation rate was a good measure of how fast something could evolve in a given amount of time. Such mutations may not have natural selection helping to establish them in the population, but they still help establish a baseline for how often a given species has mutations (and thus a chance at developing the super-rare 'helpful mutation').

Let's say one species mutates 10 times faster than the other. Doesn't that mean that it has 10 times the chance to get a NON-SILENT gene change? In other words, measuring silent mutations doesn't measure the etheral "helpful mutation" rate per se, but a species with a higher silent rate will, as I understand the theory, also have a better chance of more "helpful mutations".

Chimps and especially people have a very low mutation rate. So low that even the minor gene differences we see appear to be a lot of change in a little time. I understand a helpful mutation, if it happens, would be selected for, but if genes don't mutate much then a helpful mutation is indeed a rare unicorn. It does not matter that it will be selected for once it arrives, if it rarely arrives then I don't see how you get from A to B in the time allowed.

23 posted on 04/12/2002 3:08:55 PM PDT by Ahban
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To: Ahban
It does not matter that it will be selected for once it arrives, if it rarely arrives then I don't see how you get from A to B in the time allowed.

Thanks for pointing me to this post. I see you've missed a major point of the present study: small mutations lead to a cascade of extragenetic effects. As mutation rates slow down, notice that the correspondence between genotype and phenotype becomes more complex.

24 posted on 04/12/2002 7:12:41 PM PDT by Nebullis
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To: Ahban
The comparative data suggest that during the evolutionary process, humans somehow altered the process of gene expression in their brains, -antoher article on this subject -

Just kinda shows how desperate the evolutionists are with this finding. How does one alter one's gene expression? They refuse to change their atheistic views regardless of the evidence or how silly explaining it away makes them look.

25 posted on 04/13/2002 8:17:55 AM PDT by gore3000
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To: Nebullis
This is a good example of the difference between what the facts actaully say and what a biased interpretation of those facts leads one to understand. The study pinpointed no such "small mutations (which) lead to a cascade of extragenetic effects." The article specifically states "But changes in gene expression must in the end originate from DNA changes and the researchers do not yet know which groups of genes are responsible."

That clearly means they 1) Don't know what changes in genes are reponsible and 2) Have not established that such mutational changes have a reasonable probability of occuring in the time allowed.

Those things are ASSUMPTIONS by those who take it on Faith that evolution must be true.

Indeed, it has not been demonstrated that there is a 'pathway' of gene changes between the two that is breechable by a series of functional intermediates at all. It may be that Man and Chimps represent two genetic "islands" with no series of genetic steps between them that can produce an unbroken series of functional organisms. Or maybe there is a potential functional pathway, but it the changes are unlikely to have occured by any obserserable evolutionary process in the time allowed since the alledged 'common ancestor'. In any case, even demonstrating such a pathway had a fair chance of producing man is not proof that it DID produce man. That would still be an assumption based on faith. A 'special evolutionary process' as the article says. They cannot describe for us this process, and cannot find where or how it occurs, but the just "know" it was an evolutionary process!

As mutation rates slow down, notice that the correspondence between genotype and phenotype becomes more complex.

I would be interested to know why you think this is. I am guessing that all critters that have a low reproduction rate need a more stable DNA set. Humans and Chimps cannot afford the same mutation rate as mice! I would guess our mutation rate in HOX or whatever controls gene expression would also be lower than that of mice. After all, gene expression errors should be able to produce unfit organsims just as well as regular gene errors.

26 posted on 04/13/2002 8:20:48 AM PDT by Ahban
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