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On 3/23/18 8:25 PM, hari kumar via Marxism wrote:
Hi: I would be grateful of the whole article in some way could be posted -
especially interested in this issue. Would that be possible? Thanks for
considering,
Cheers Hari Kumar
How Genetics Is Changing Our Understanding of ‘Race’
Gray Matter
By DAVID REICH MARCH 23, 2018
In 1942, the anthropologist Ashley Montagu published “Man’s Most
Dangerous Myth: The Fallacy of Race,” an influential book that argued
that race is a social concept with no genetic basis. A classic example
often cited is the inconsistent definition of “black.” In the United
States, historically, a person is “black” if he has any sub-Saharan
African ancestry; in Brazil, a person is not “black” if he is known to
have any European ancestry. If “black” refers to different people in
different contexts, how can there be any genetic basis to it?
Beginning in 1972, genetic findings began to be incorporated into this
argument. That year, the geneticist Richard Lewontin published an
important study of variation in protein types in blood. He grouped the
human populations he analyzed into seven “races” — West Eurasians,
Africans, East Asians, South Asians, Native Americans, Oceanians and
Australians — and found that around 85 percent of variation in the
protein types could be accounted for by variation within populations and
“races,” and only 15 percent by variation across them. To the extent
that there was variation among humans, he concluded, most of it was
because of “differences between individuals.”
In this way, a consensus was established that among human populations
there are no differences large enough to support the concept of
“biological race.” Instead, it was argued, race is a “social construct,”
a way of categorizing people that changes over time and across countries.
It is true that race is a social construct. It is also true, as Dr.
Lewontin wrote, that human populations “are remarkably similar to each
other” from a genetic point of view.
But over the years this consensus has morphed, seemingly without
questioning, into an orthodoxy. The orthodoxy maintains that the average
genetic differences among people grouped according to today’s racial
terms are so trivial when it comes to any meaningful biological traits
that those differences can be ignored.
The orthodoxy goes further, holding that we should be anxious about any
research into genetic differences among populations. The concern is that
such research, no matter how well-intentioned, is located on a slippery
slope that leads to the kinds of pseudoscientific arguments about
biological difference that were used in the past to try to justify the
slave trade, the eugenics movement and the Nazis’ murder of six million
Jews.
I have deep sympathy for the concern that genetic discoveries could be
misused to justify racism. But as a geneticist I also know that it is
simply no longer possible to ignore average genetic differences among
“races.”
Groundbreaking advances in DNA sequencing technology have been made over
the last two decades. These advances enable us to measure with exquisite
accuracy what fraction of an individual’s genetic ancestry traces back
to, say, West Africa 500 years ago — before the mixing in the Americas
of the West African and European gene pools that were almost completely
isolated for the last 70,000 years. With the help of these tools, we are
learning that while race may be a social construct, differences in
genetic ancestry that happen to correlate to many of today’s racial
constructs are real.
Recent genetic studies have demonstrated differences across populations
not just in the genetic determinants of simple traits such as skin
color, but also in more complex traits like bodily dimensions and
susceptibility to diseases. For example, we now know that genetic
factors help explain why northern Europeans are taller on average than
southern Europeans, why multiple sclerosis is more common in
European-Americans than in African-Americans, and why the reverse is
true for end-stage kidney disease.
I am worried that well-meaning people who deny the possibility of
substantial biological differences among human populations are digging
themselves into an indefensible position, one that will not survive the
onslaught of science. I am also worried that whatever discoveries are
made — and we truly have no idea yet what they will be — will be cited
as “scientific proof” that racist prejudices and agendas have been
correct all along, and that those well-meaning people will not
understand the science well enough to push back against these claims.
This is why it is important, even urgent, that we develop a candid and
scientifically up-to-date way of discussing any such differences,
instead of sticking our heads in the sand and being caught unprepared
when they are found.
To get a sense of what modern genetic research into average biological
differences across populations looks like, consider an example from my
own work. Beginning around 2003, I began exploring whether the
population mixture that has occurred in the last few hundred years in
the Americas could be leveraged to find risk factors for prostate
cancer, a disease that occurs 1.7 times more often in self-identified
African-Americans than in self-identified European-Americans. This
disparity had not been possible to explain based on dietary and
environmental differences, suggesting that genetic factors might play a
role.
Self-identified African-Americans turn out to derive, on average, about
80 percent of their genetic ancestry from enslaved Africans brought to
America between the 16th and 19th centuries. My colleagues and I
searched, in 1,597 African-American men with prostate cancer, for
locations in the genome where the fraction of genes contributed by West
African ancestors was larger than it was elsewhere in the genome. In
2006, we found exactly what we were looking for: a location in the
genome with about 2.8 percent more African ancestry than the average.
When we looked in more detail, we found that this region contained at
least seven independent risk factors for prostate cancer, all more
common in West Africans. Our findings could fully account for the higher
rate of prostate cancer in African-Americans than in European-Americans.
We could conclude this because African-Americans who happen to have
entirely European ancestry in this small section of their genomes had
about the same risk for prostate cancer as random Europeans.
Did this research rely on terms like “African-American” and
“European-American” that are socially constructed, and did it label
segments of the genome as being probably “West African” or “European” in
origin? Yes. Did this research identify real risk factors for disease
that differ in frequency across those populations, leading to
discoveries with the potential to improve health and save lives? Yes.
While most people will agree that finding a genetic explanation for an
elevated rate of disease is important, they often draw the line there.
Finding genetic influences on a propensity for disease is one thing,
they argue, but looking for such influences on behavior and cognition is
another.
But whether we like it or not, that line has already been crossed. A
recent study led by the economist Daniel Benjamin compiled information
on the number of years of education from more than 400,000 people,
almost all of whom were of European ancestry. After controlling for
differences in socioeconomic background, he and his colleagues
identified 74 genetic variations that are over-represented in genes
known to be important in neurological development, each of which is
incontrovertibly more common in Europeans with more years of education
than in Europeans with fewer years of education.
It is not yet clear how these genetic variations operate. A follow-up
study of Icelanders led by the geneticist Augustine Kong showed that
these genetic variations also nudge people who carry them to delay
having children. So these variations may be explaining longer times at
school by affecting a behavior that has nothing to do with intelligence.
This study has been joined by others finding genetic predictors of
behavior. One of these, led by the geneticist Danielle Posthuma, studied
more than 70,000 people and found genetic variations in more than 20
genes that were predictive of performance on intelligence tests.
Is performance on an intelligence test or the number of years of school
a person attends shaped by the way a person is brought up? Of course.
But does it measure something having to do with some aspect of behavior
or cognition? Almost certainly. And since all traits influenced by
genetics are expected to differ across populations (because the
frequencies of genetic variations are rarely exactly the same across
populations), the genetic influences on behavior and cognition will
differ across populations, too.
You will sometimes hear that any biological differences among
populations are likely to be small, because humans have diverged too
recently from common ancestors for substantial differences to have
arisen under the pressure of natural selection. This is not true. The
ancestors of East Asians, Europeans, West Africans and Australians were,
until recently, almost completely isolated from one another for 40,000
years or longer, which is more than sufficient time for the forces of
evolution to work. Indeed, the study led by Dr. Kong showed that in
Iceland, there has been measurable genetic selection against the genetic
variations that predict more years of education in that population just
within the last century.
To understand why it is so dangerous for geneticists and anthropologists
to simply repeat the old consensus about human population differences,
consider what kinds of voices are filling the void that our silence is
creating. Nicholas Wade, a longtime science journalist for The New York
Times, rightly notes in his 2014 book, “A Troublesome Inheritance:
Genes, Race and Human History,” that modern research is challenging our
thinking about the nature of human population differences. But he goes
on to make the unfounded and irresponsible claim that this research is
suggesting that genetic factors explain traditional stereotypes.
One of Mr. Wade’s key sources, for example, is the anthropologist Henry
Harpending, who has asserted that people of sub-Saharan African ancestry
have no propensity to work when they don’t have to because, he claims,
they did not go through the type of natural selection for hard work in
the last thousands of years that some Eurasians did. There is simply no
scientific evidence to support this statement. Indeed, as 139
geneticists (including myself) pointed out in a letter to The New York
Times about Mr. Wade’s book, there is no genetic evidence to back up any
of the racist stereotypes he promotes.
Another high-profile example is James Watson, the scientist who in 1953
co-discovered the structure of DNA, and who was forced to retire as head
of the Cold Spring Harbor Laboratories in 2007 after he stated in an
interview — without any scientific evidence — that research has
suggested that genetic factors contribute to lower intelligence in
Africans than in Europeans.
At a meeting a few years later, Dr. Watson said to me and my fellow
geneticist Beth Shapiro something to the effect of “When are you guys
going to figure out why it is that you Jews are so much smarter than
everyone else?” He asserted that Jews were high achievers because of
genetic advantages conferred by thousands of years of natural selection
to be scholars, and that East Asian students tended to be conformist
because of selection for conformity in ancient Chinese society.
(Contacted recently, Dr. Watson denied having made these statements,
maintaining that they do not represent his views; Dr. Shapiro said that
her recollection matched mine.)
What makes Dr. Watson’s and Mr. Wade’s statements so insidious is that
they start with the accurate observation that many academics are
implausibly denying the possibility of average genetic differences among
human populations, and then end with a claim — backed by no evidence —
that they know what those differences are and that they correspond to
racist stereotypes. They use the reluctance of the academic community to
openly discuss these fraught issues to provide rhetorical cover for
hateful ideas and old racist canards.
This is why knowledgeable scientists must speak out. If we abstain from
laying out a rational framework for discussing differences among
populations, we risk losing the trust of the public and we actively
contribute to the distrust of expertise that is now so prevalent. We
leave a vacuum that gets filled by pseudoscience, an outcome that is far
worse than anything we could achieve by talking openly.
If scientists can be confident of anything, it is that whatever we
currently believe about the genetic nature of differences among
populations is most likely wrong. For example, my laboratory discovered
in 2016, based on our sequencing of ancient human genomes, that “whites”
are not derived from a population that existed from time immemorial, as
some people believe. Instead, “whites” represent a mixture of four
ancient populations that lived 10,000 years ago and were each as
different from one another as Europeans and East Asians are today.
So how should we prepare for the likelihood that in the coming years,
genetic studies will show that many traits are influenced by genetic
variations, and that these traits will differ on average across human
populations? It will be impossible — indeed, anti-scientific, foolish
and absurd — to deny those differences.
For me, a natural response to the challenge is to learn from the example
of the biological differences that exist between males and females. The
differences between the sexes are far more profound than those that
exist among human populations, reflecting more than 100 million years of
evolution and adaptation. Males and females differ by huge tracts of
genetic material — a Y chromosome that males have and that females
don’t, and a second X chromosome that females have and males don’t.
Most everyone accepts that the biological differences between males and
females are profound. In addition to anatomical differences, men and
women exhibit average differences in size and physical strength. (There
are also average differences in temperament and behavior, though there
are important unresolved questions about the extent to which these
differences are influenced by social expectations and upbringing.)
How do we accommodate the biological differences between men and women?
I think the answer is obvious: We should both recognize that genetic
differences between males and females exist and we should accord each
sex the same freedoms and opportunities regardless of those differences.
It is clear from the inequities that persist between women and men in
our society that fulfilling these aspirations in practice is a
challenge. Yet conceptually it is straightforward. And if this is the
case with men and women, then it is surely the case with whatever
differences we may find among human populations, the great majority of
which will be far less profound.
An abiding challenge for our civilization is to treat each human being
as an individual and to empower all people, regardless of what hand they
are dealt from the deck of life. Compared with the enormous differences
that exist among individuals, differences among populations are on
average many times smaller, so it should be only a modest challenge to
accommodate a reality in which the average genetic contributions to
human traits differ.
It is important to face whatever science will reveal without prejudging
the outcome and with the confidence that we can be mature enough to
handle any findings. Arguing that no substantial differences among human
populations are possible will only invite the racist misuse of genetics
that we wish to avoid.
David Reich is a professor of genetics at Harvard and the author of the
forthcoming book “Who We Are and How We Got Here: Ancient DNA and the
New Science of the Human Past,” from which this article is adapted.
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