Ardhanariswar said:
OK HERE YOU GO - i hope this is interesting reading
The more closely researchers examine the human genome (the complement of genetic material encased in the heart of almost every cell of the body) the more most of them are convinced that the standard labels used to distinguish people by "race" have little biological meaning.
They say that while it may seem easy to tell at a glance whether a person is Caucasian, African or Asian, the ease dissolves when one probes beneath surface characteristics and scans the genome for DNA hallmarks of "race." As it turns out, scientists say, the human species is so evolutionarily young, and its migratory patterns so wide, restless and rococo, that it has simply not had a chance to divide itself into separate biological groups in any but the most superficial ways.
"Race is a social concept, not a scientific one," said Dr. J. Craig Venter, head of the Celera Genomics Corporation in Rockville, Md. "We all evolved in the last 100,000 years from the same small number of tribes that migrated out of Africa and colonized the world."
Dr. Venter and scientists at the National Institutes of Health recently announced that they had put together a draft of the entire sequence of the human genome, and the researchers had unanimously declared, there is only one race -- the human race. Dr. Venter and other researchers say that those traits most commonly used to distinguish one race from another, like skin and eye color, or the width of the nose, are traits controlled by a relatively few number of genes, and thus have been able to change rapidly in response to extreme environmental pressures during the short course of Homo Sapiens history.
Equatorial populations evolved dark skin, to protect against ultraviolet radiation, while people in northern latitudes evolved pale skin, in order to produce vitamin D from pale sunlight. About .01 percent of our genes are reflected in our external appearances and because this tiny percent together with the high percentage of ignorance many humans were relegated to enslavement and genocide.
By contrast with the tiny number of genes that make some people dark-skinned and doe-eyed, and others as pale as napkins, scientists say that traits like intelligence, artistic talent and social skills are likely to be shaped by thousands, if not tens of thousands, of the 80,000 or so genes in the human genome, all working in complex combinations.The possibility of such gene networks shifting their interrelationships wholesale in the course of humanity's brief foray across the globe, and being skewed in significant ways according to "race" is "a bogus idea," said Dr. Aravinda Chakravarti, a geneticist at CaseWesternUniversity in Cleveland.
The differences that we see in skin color do not translate into widespread biological differences that are unique to groups. They more allow us to reflect on the socializing that went along with the development of our differences that enabled us to survive in a given environment.
Dr. Jurgen K. Naggert, a geneticist at the Jackson Laboratory in Bar Harbor, Me., said: "These big groups that we characterize as races are too heterogeneous to lump together in a scientific way.
Since the African emigrations began, a mere 7,000 generations have passed. In addition, because the founding population of immigrants was small, it could only take so much genetic variation with it. Because of that combination, (a limited founder population and a short time since dispersal) humans are strikingly homogeneous, differing from one another only once in a thousand subunits of the genome.
"We are a small population grown large in the blink of an eye," Dr. Lander said. "We are a little village that's grown all over the world, and we retain the genetic variation seen in that little village."
The human genome is large, though, composed of three billion-odd subunits, or bases, which means that even a tiny percentage of variation from one individual to the next amounts to a sizable number of genetic discrepancies.
The question is, where in the genome is that variation found, and how is it distributed among different populations?
Through global sampling of neutral genetic markers (stretches of genetic material that do not help create the body's functioning proteins but instead are composed of so-called 'junk DNA') researchers have found that, on average, 88 percent to 90 percent of the differences between people occur within their local populations, while only about 10 percent to 12 percent of the differences distinguish one population, or race, from another.
To put it another way, the citizens of any given village in the world, whether in Scotland or Tanzania, hold 90 percent of the genetic variability that humanity has to offer.
However, that 90/10 ratio is just an average, and refers only to 'junk-DNA' markers.
For the genetic material that encodes proteins, the picture is somewhat more complex. Many workhorse genes responsible for basic organ functions show virtually no variability from individual to individual, which means they are even less "race specific" than are neutral genetic markers.
Some genes, notably those of the immune system, show enormous variability, but the variability does not track with racial groupings. A few group differences are more than skin deep. Among the most famous examples are the elevated rates of sickle-cell anemia among African-Americans and of betathalassemia, another hemoglobin disorder, among those of Mediterranean heritage. Both traits evolved to help the ancestors of these groups resist malaria infection, but both prove lethal when inherited in a double dose. As with differences in skin pigmentation, the means to do so was through the alteration of a single gene.
Another cause of group differences is the so-called founder effect. In such cases, the high prevalence of an unusual condition in a population can be traced to a founding ancestor who happened to carry a novel mutation into the region. Over many generations of comparative isolation and inbreeding, the community, like it or not, became "enriched" with the founder's disorder. The founder effect explains the high incidence of Huntington's neuro-degenerative disease in the LakeMaracaibo region of Venezuela, and of Tay-Sachs disease among Ashkenazi Jews.
Dr. Naggert emphasized that medical geneticists had a much better chance of unearthing these founder effects by scrutinizing small, isolated and well-defined populations, like the northern Finns, the Basques of Spain, or the Amish of Pennsylvania, than they did by going after "races." Dr. Sonia S. Anand, an assistant professor of medicine at McMasterUniversity in Ontario, proposed that clinicians think about ethnicity rather than race when seeking clues to how disease patterns differ from one group to the next.
Ethnicity is a broad concept that encompasses both genetics and culture. Thinking about ethnicity is a way to bring together questions of a person's biology, lifestyle and diet. Ethnicity is about phenotype and genotype, and it allows people to look at differences between groups in another way. However, studying the effects of racial labeling is imperative and a prerequisite to correcting the errors of the past.
In investigating the reasons behind the high incidence of cardiovascular disease among people from the Indian subcontinent, for example, Dr. Anand discovered that Indians had comparatively elevated amounts of clotting factors in their blood. Beyond tallying up innate traits, she also takes into account how Indian culture and life habits may pose added risks for heart disease.
Abstracts from various scientific articles at Nature .com and news reports.
, you would see that genetics has very little or next to none role to play in racial characteristics. these characteristics could be accepted as genetic if and only if a certain threshold of genetic material is responsible specifically for the trait. so two minimum requirements, a. the said genetic material should be specifically responsible for a certain trait and should be clearly identifiable, meaning it should be scientifically significant.