Posted on 12/21/2002 3:54:34 AM PST by Pharmboy
Scientists studying the DNA of 52 human groups from around the world have concluded that people belong to five principal groups corresponding to the major geographical regions of the world: Africa, Europe, Asia, Melanesia and the Americas.
The study, based on scans of the whole human genome, is the most thorough to look for patterns corresponding to major geographical regions. These regions broadly correspond with popular notions of race, the researchers said in interviews.
The researchers did not analyze genes but rather short segments of DNA known as markers, similar to those used in DNA fingerprinting tests, that have no apparent function in the body.
"What this study says is that if you look at enough markers you can identify the geographic region a person comes from," said Dr. Kenneth Kidd of Yale University, an author of the report.
The issue of race and ethnicity has forced itself to biomedical researchers' attention because human populations have different patterns of disease, and advances in decoding DNA have made it possible to try and correlate disease with genetics.
The study, published today in Science, finds that "self-reported population ancestry likely provides a suitable proxy for genetic ancestry." In other words, someone saying he is of European ancestry will have genetic similarities to other Europeans.
Using self-reported ancestry "is less expensive and less intrusive" said Dr. Marcus Feldman of Stanford University, the senior author of the study. Rather than analyzing a person's DNA, a doctor could simply ask his race or continent of origin and gain useful information about their genetic make-up.
Several scientific journal editors have said references to race should be avoided. But a leading population geneticist, Dr. Neil Risch of Stanford University, argued recently that race was a valid area of medical research because it reflects the genetic differences that arose on each continent after the ancestral human population dispersed from its African homeland.
"Neil's article was theoretical and this is the data that backs up what he said," Dr. Feldman said.
The new result is based on blood samples gathered from around the world as part of the Human Genome Diversity Project, though on a much less ambitious scale than originally intended. Dr. Feldman and his colleagues analyzed the DNA of more than 1,000 people at some 400 markers. Because the sites have no particular function, they are free to change or mutate without harming the individual, and can become quite different over the generations.
The Science authors concluded that 95 percent of the genetic variations in the human genome is found in people all over the world, as might be expected for a small ancestral population that dispersed perhaps as recently as 50,000 years ago.
But as the first human populations started reproducing independently from one another, each started to develop its own pattern of genetic differences. The five major continental groups now differ to a small degree, the Science article says, as judged by the markers. The DNA in the genes is subject to different pressures, like those of natural selection.
Similar divisions of the world's population have been implied by earlier studies based on the Y chromosome, carried by males, and on mitochondrial DNA, bequeathed through the female line. But both elements constitute a tiny fraction of the human genome and it was not clear how well they might represent the behavior of the rest of the genome.
Despite the large shared pool of genetic variation, the small number of differences allows the separate genetic history of each major group to be traced. Even though this split broadly corresponds with popular notions of race, the authors of Science article avoid using the word, referring to the genetic patterning they have found with words like "population structure" and "self-reported population ancestry."
But Dr. Feldman said the finding essentially confirmed the popular conception of race. He said precautions should be taken to make sure the new data coming out of genetic studies were not abused.
"We need to get a team of ethicists and anthropologists and some physicians together to address what the consequences of the next phase of genetic analysis is going to be," he said.
Some diseases are much commoner among some ethnic groups than others. Sickle cell anemia is common among Africans, while hemochromatosis, an iron metabolism disorder, occurs in 7.5 percent of Swedes. It can therefore be useful for a doctor to consider a patient's race in diagnosing disease. Researchers seeking the genetic variants that cause such diseases must take race into account because a mixed population may confound their studies.
The new medical interest in race and genetics has left many sociologists and anthropologists beating a different drum in their assertions that race is a cultural idea, not a biological one. The American Sociological Association, for instance, said in a recent statement that "race is a social construct" and warned of the "danger of contributing to the popular conception of race as biological."
Dr. Alan Goodman, a physical anthropologist at Hampshire College and an adviser to the association, said, "there is no biological basis for race." The clusters shown in the Science article were driven by geography, not race, he said.
But Dr. Troy Duster, a sociologist at New York University and chairman of the committee that wrote the sociologists' statement on race, said it was meant to talk about the sociological implications of classifying people by race and was not intended to discuss the genetics.
"Sociologists don't have the competence to go there," he said.
Only those few who possessed the then-rare gene for nostril hair survived.
The study did not look at genes. It did not say genes follow geography. You still don't understand the basics of either biology or this study you try to use for your own idiosyncratic ends.
I've looked at your comments and realize you have no idea scientifically what you are talking about, which is fine as most people wouldn't.
But I see there is an overriding component to your posts - you have an agenda.
You guys try to turn real science in to pseudoscience in order to propagandize your weird xenophobic anti-American garbage.
And where in my posts were there any hints of xenophobia or "anti-Americanism."
You sound like the one with the agenda, bub.
Here's what the Times said of the study, quoting the study itself: The study, published today in Science, finds that "self-reported population ancestry likely provides a suitable proxy for genetic ancestry." In other words, someone saying he is of European ancestry will have genetic similarities to other Europeans.
Yep--just like you said, the study did not say that genes follow geography. Fool--take a reading comprehension course at your local community college.
Resistance to smallpox?
Ability to metabolize alcohol.
Two, "genetic ancestry" does not mean genes. You do not understand what they looked at. The markers are not genes.
And, although I quoted from the article, I also quoted from the study itself--which you, of course, ignored ("self-reported population ancestry likely provides a suitable proxy for genetic ancestry").
But never-you-mind: keep denying reality and recite the mantra: "blank slate, all environment, no genetic difference between groups or individuals that's meaningful, etc. etc."
Now, you are quite ignorant and apparently indifferent to knowledge or accuracy.
You have problems. Nothing I am saying is controversial or something anyone should take umbrage at.
You could even learn something.
I never said any of this. Nor did I ever imply any of it.
It does point out a bit where you are coming from and why you have problems discussing science dispassionately.
Ability to metabolize alcohol.
Here's another one: ability to digest lactose.
And, it was YOU who began the nastiness on the thread. Read all of your posts...you're the one who is emotionally involved and wants to deny reality--not me. But, it's probably better to be tall and happy than tall and smart.
Buh-bye.
I did some thinking on that. Where in the world would there be a sure supply of food for 2-5 years? The polar regions. When an animal fell over dead (for what-ever reason), he would be immediately frozen and preserved...a ready food supply, deep frozen. HUH?
So I should tell my wife to quit complaining -- I have superior genes!
Mountains would work in that respect. Thinking of 5 or so bands of humans, separated by entire continents for a few 1000 years.
Don't overlook the obvious -- canibalism.
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