Do Races Differ? Not Really, DNA Shows nytimes.com
This topic was batted around recently, though I'm not sure if you were a participant, Joan. I put it up for general interest, anyway.
In these glossy, lightweight days of an
election year, it seems, they can't build
metaphorical tents big or fast enough for
every politician who wants to pitch one up
and invite the multicultural folds to "Come on
under!" The feel-good message that both
parties seek to convey is: regardless of race
or creed, we really ARE all kin beneath the
skin.
Yet whatever the calculated quality of this
new politics of inclusion, its sentiment
accords firmly with scientists' growing
knowledge of the profound genetic fraternity
that binds together human beings of the most
seemingly disparate origins.
Scientists have long suspected that the racial
categories recognized by society are not
reflected on the genetic level.
But the more closely that 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 or no 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 or
"races" 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.
And so equatorial populations evolved dark
skin, presumably to protect against ultraviolet
radiation, while people in northern latitudes
evolved pale skin, the better to produce
vitamin D from pale sunlight.
"If you ask what percentage of your genes is
reflected in your external appearance, the
basis by which we talk about race, the
answer seems to be in the range of .01
percent," said Dr.
Harold P. Freeman, the chief executive,
president and director of surgery at North
General Hospital in Manhattan, who has
studied the issue of biology and race. "This is
a very, very minimal reflection of your genetic
makeup."
Unfortunately for social harmony, the human
brain is exquisitely attuned to differences in
packaging details, prompting people to exaggerate the significance of
what has come to be called race, said Dr. Douglas C. Wallace, a
professor of molecular genetics at Emory University School of Medicine
in Atlanta.
"The criteria that people use for race are based entirely on external
features that we are programmed to recognize," he said.
"And the reason we're programmed to recognize them is that it's vitally
important to our species that each of us be able to distinguish one
individual from the next.
Our whole social structure is based on visual cues, and we've been
programmed to recognize them, and to recognize individuals."
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 combinatorial fashion.
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 Case Western University in
Cleveland.
"The differences that we see in skin color do not translate into
widespread biological differences that are unique to groups."
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.
If you're doing a DNA study to look for markers for a particular disease,
you can't use 'Caucasians' as a group. They're too diverse.
Well, it being the NYT, the other side gets its say after this part, but I leave that to the reader. Too long a quote already.
Cheers, Dan. |
