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>Posted on 08/31/2005 6:18:11 PM PDT by neverdem
The first detailed genetic comparison between humans and chimpanzees shows that 96 per cent of the DNA sequence is identical in the two species. But there are significant differences, particularly in genes relating to sexual reproduction, brain development, immunity and the sense of smell.
An international scientific consortium publishes the genome of the chimpanzee, the animal most closely related to homo sapiens on Thursday in the journal Nature. It is the fourth mammal to have its full genome sequenced, after the mouse, rat and human being.
Some of the scientific analysis of the 3bn chemical "letters" of the chimp's genetic code focused on its remarkable closeness to the human genome. After 6m years of separate evolution, the differences between chimp and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice.
But most scientists are concentrating on the differences. The vast majority of these probably have little biological significance, said Simon Fisher of the Wellcome Trust Centre for Human Genetics at Oxford: "The big challenge for the future is to pinpoint the tiny subset of differences that account for the origins of unusual human traits, such as complex language."
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| External website: Read Nature's interactive report on the chimp genome >Click here |
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The preliminary evidence suggests that the outstanding size and complexity of the human brain owes less to the evolution of new human genes than to the different way existing genes produce proteins as the human brain grows in the foetus and during infancy. Genes for transcription factors - molecules that regulate the activity of other genes and play a vital role in embryonic development - are evolving more quickly in humans than in chimps.
Three key genes involved in the human inflammatory response to disease are missing in chimps, which may explain some of the differences between the two immune systems. On the other hand humans have lost a gene for an enzyme that may protect other animals against Alzheimer's disease.
The clearest differences to emerge from the analysis are in the Y (male) sex chromosome. While the human Y chromosome has maintained its count of 27 active gene families over 6m years, some have mutated and become inactive on its chimp counterpart.
This finding contradicts the popular view that the human Y chromosome is withering away because it has no genetic "mate" with which to swap genes - a process that repairs damaged DNA on other chromosomes. Presumably an alternative repair mechanism has evolved in humans but not in chimps.
David Page of the Whitehead Institute for Biomedical Research suggested that mating habits in the two species might explain the difference. Because male and female chimps mate with multiple partners there is stronger selective pressure on sperm-producing genes and conversely less pressure on evolution to preserve other genes on the Y chromosome in the apes than in largely monogamous humans.
But we know that if one or two genes are out of place it can have horrible results. I have a genetic condtion that is caused by one faulty gene. And because of that I have to deal with benign tumors for the rest of my life.
So a 4% difference is huge.
Significant but remember, Kool-Aid and Wine Coolers are about 96% identical too.
Same thing as saying: Democrat and Republican DNA is 96% identical but it's the missing 4% which makes all the difference in the world.
And I thought he was the missing 4%.
Depends on how you look at it. The differences between chimp and human are of degree, not kind. Physically, everything a human has a chimp also has, and pretty much in the same location.
I was taught while at university, that Chimps and Humans were only 1 to 1.8% different (results from the inference given in nucleotide hybridization were used), so I have always thought it was a 98 to 98.2% match. I wanted to make sure so I looked at years of notes including notes from 1992 and 93 after graduating and attending several lectures by the great Stephen J. Gould, Vince Sarich and Karl Sigmund. They all said 98 or higher. In fact I remember Sarich insisting upon a 99% match while debating some creationist clown just a few years ago.
Four percent difference is too large and is much more than it appears to me using observation with the naked eye. Some Chimps seem quite Human, much closer than the looters we witness in NOLA, and I think the findings are not the last word, it has to be closer.
No doubt, I just could not find as "precious" a picture to make my point ;)
Are you too smug to notice the irony in your post? You've continually whined about the use of sarcasm in response to your posts, yet you use an equal amount of sarcasm in those same posts. I'm sure you'll contend that you were being ironic, but you clearly lack the subtlety for that to be true.
Not as such. However, I can go back to where my sheets originated, and there are more of them. They are a few years old, so the exact same ones won't be there. Instead, it is more likely that the manufacturer will have taken the most successful attributes of my sheets into account when designing the next generation of sheets. Perhaps consumers liked the pattern but preferred the thread count of a different set and the color of yet another set, thus causing the manufacturer to create a new style of sheets that more reflect the tastes of consumers. In essence, the sheets would evolve based on natural selection. If the customers love the new sheets, more of the same will be produced. That doesn't mean they don't require a designer working the controls.
[Because male and female chimps mate with multiple partners there is stronger selective pressure on sperm-producing genes and conversely less pressure on evolution to preserve other genes on the Y chromosome in the apes than in largely monogamous humans.]
All right! This is my new excuse to be promiscuous.
Great post!
They were probably refering to transcribed DNA which would be in the 99% range, while this article is refering to all the DNA, which is 96%.
Yes, but I wouldn't have traded a foot for it.
I will look into it, but you might have something.
Has Chimp DNA even been completely sequenced yet? If not, how can one say with certainty that the coding regions are almost identical? One would have to resort to statistical analysis, which in this case is fraught with difficulties.
That near identity speaks volumes about the relationship between us and chimps.
The 'volumes' in that 4% contain probably around 120 million base pairs, equivalent to approximately 12 million words, or about 40 large volumes of information. 'Near identity' and 'the relationship between us and chimps' is in the eye of the beholder.
Cordially,
...Genes for transcription factors - molecules that regulate the activity of other genes and play a vital role in embryonic development - are evolving more quickly in humans than in chimps.... While the human Y chromosome has maintained its count of 27 active gene families over 6m years, some have mutated and become inactive on its chimp counterpart.
Does this mean that Fast (E)evolution produces Slow (E)evolution? How does a putative single, self-same Evolutionary power purportedly produce such remarkable degrees of contrarian stasis and change?
Cordially,
The actual gram amount of DNA has nothing to do with anything relating to base pair similarities between species, or with any sort of strutcural functional considerations.
You win the prize for most off the wall meaningless comment that demonstrates absolute ignorance on a subject.
Prior to this I actually thought you knew what DNA was.
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