送交者: xj 于 2005-3-16, 01:54:22:
回答: NYTIME上最近又出了篇种族与基因的文章，很多人特不高兴 由 xj 于 2005-3-16, 01:52:39:
内部消息 ：-)
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A Racialized Genomics: Shiny, Bright and Wrong
Armand Marie Leroi announces in his Times op-ed that race
is biologically real (New York Times, March 14). The
crusty trope that race is a social artifact crumbles in
the face of the bright new genomics, he asserts. Genetic
variation may be greater within-groups than
between-groups, as Richard Lewontin pointed out back in
the dark ages of the 1970s, but only for single genes.
Taken together, across genetic loci allelic distributions
correlate into clusters long recognized as the five races:
European, East Asian, African, Amerindian, and
Australasian. So suck it up, constructionists, race is
biologically intrinsic.
Moreover, get out of the way. The recognition that race is
inherently biological, Leroi writes, can improve medical
care, "as different races are prone to different
diseases." African-Americans, for example, suffer greater
prevalences of heart disease and prostate cancer. Even if
such differences arise from socioeconomic causes, Leroi
argues, we should--ignoring the man behind the
curtain--embrace geneticists' very important mission,
"searching for racial differences in the frequencies of
genetic variants that cause diseases."
And yet much of Leroi's article unravels his own argument.
Leroi takes population geneticists to task for caving into
political correctness by investigating "ethnic groups," a
euphemism that conflates human differences across scale.
Never mind that population geneticists prefer the term
less out of deference to present sensibilities than to the
data themselves. Work by Luigi Cavalli-Sforza's group
(Cavalli-Sforza 2001, Underhill 2003), among others, show
human history--back to our species' origins--to be marked
by layers of migration sweeping back and forth across the
continents, gurgling here and there into local pools of
idiosyncratic admixture. While the resulting genetic
frequencies do not embody a homogenous mush, neither does
a stark black and white favored by the new racialists
result. Instead, genetic maps are marked by fine-scaled
and functionally important population gradients.
Leroi recognizes these complications, but still asks us to
ignore them in favor of, ironically enough, a social
construct. Just as it is difficult to talk of the world's
physical topography in terms of multiple contour lines and
elevations and easier to do so in general terms, such as
grouping a variety of tall peaks as "mountain ranges,"
"so, too, it is with the genetic topography of our
species." Grouping the billion people of European descent
together as a race is easier, "a shorthand that enables us
to speak sensibly...about genetic rather than cultural or
political differences." So, it would appear that bleaching
out complications when discussing human variation makes
life easier. Of course, as those dastardly social
constructionists are apt to ask, easier for whom?
For one, according to Leroi, the pharmaceutical companies.
As race can affect medical treatment, "many new drugs are
now labeled with warnings that they may not work in some
ethnic or racial groups." That such effects need not be
predominantly biological in origin apparently matters
little. Leroi admits differences among races arise from
population averages alone. But as we are unlikely to have
individuals' genomes sequenced anytime soon, and
presumably won't be able to individualize medical
treatment that way, we'll just have to accept a racialized
medical genetics. Nothing like an argument of expediency
to convince a crowd. The pharmaceutical companies are
doing it, so get with it, baby!
Here, Leroi, an evolutionary developmental biologist,
bumbles back into the typology the Darwinian revolution
revoked. As Ernst Mayr (1976, 2004) explained, until the
early 19th century biologists classified species in
essentialist terms. A specific type or specimen defined a
species and any variation from the type was considered
deviant or unreal. In statistical terms, a centroid
measure such as the mean phenotype defined the species,
while the variance was thought noise. Typological
definitions accounted for the differences among species
and, without variation, explained the impossibility of
evolution.
Darwin and his colleagues turned biology on its head. The
population thinking they introduced emphasized the
variation in populations. As natural history studies
accumulated, it became apparent individual organisms
varied in just about any and all characteristics, both
across and within species. Individuals even changed over
the course of their lifespans. Here, averages became
thought of as constructs and the variances the reality.
Variation's reality proved fundamental to Darwin's natural
selection. The greater the variation in the population,
the faster natural selection works and adaptations arise.
Mayr declared the distinction between the two kinds of
thinking about populations couldn't be overemphasized. He
noted its social consequences. Essentialisms form the core
of all racialist theories of human populations, in which
all members of a race are thought exhibiting
characteristics of the race type. Even as population
biologists use differences in averages to heuristically
distinguish populations--human or otherwise--by race or
subspecies, individuals clearly vary in all traits and can
be reaggregated from trait to trait.
Leroi and the new racialists are trying to get around
population thinking by correlating aggregations across
loci, as a set of emergent essentialisms. Funny, though,
that within the very medical framework they are attempting
to define, as they live by the sword of correlation, so
must they die by that sword. When we correlate putative
racial continua across diseases, the same groups are time
and again imputed the most susceptible alleles.
African-Americans suffer not only greater prevalence of
and/or lesser survivorship from heart disease (Andrews et
al. 2001) and prostate cancer (Reddy et al. 2003), as
Leroi notes, but also similarly for kidney cancer
(Vaishampayan et al. 2003), breast cancer (Ghafoor et al.
2003), cervical cancer (Jemal et al. 2004), oral cancers
(Shavers et al. 2003), lung cancer (Stellman et al. 2003),
colorectal cancer (Baquet and Commiskey 1999), pancreatic
cancer (Silverman et al. 2003), endometrical cancer
(Randall and Armstrong 2003), lymphomas (Briggs et al.
2003), tooth loss (Gilbert et al. 2003), obesity and
diabetes (Cossrow and Faulkner 2004), chronic asthma
(Boudreaux et al. 2003), Lupus nephritis (Lea 2002), HIV
(Torian et al. 2002), hepatitis B and syphilis (Schrag et
al. 2003), gonorrhea (Dombrowski et al. 2004), arthritis
(Dunlop et al. 2001), stroke (Ruland and Gorelick 2005),
and so on.
Are we to assume that African-Americans and other minority
groups carry the most susceptible alleles for every one of
these diseases? Can we pretend that the vagaries of
mutational chance just happened to deal African-Americans
the greatest susceptibilities for every ailment on our
awful list? While there are indeed well-documented
examples of illness with important genetic roots, for a
framework addressing health disparities we'd exert greater
impact by placing our attention back on the man behind the
curtain. Racism and other sources of population-level
stress have, by way of their emotional and material
deprivations, definitional effect on individuals as early
as conception, as well as on the populations of which they
are a part. Racism shapes ontogeny, regardless of allelic
frequencies. And it's to that relationship and its
overdetermination of the correlation of diseases where
research and social action need to be directed.
For most geneticists, then, there appear two unpleasant
paths. One involves accepting population disparities in
health outcomes are largely driven by social constructs
such as racism, rendering genetics' role ancillary. A
second path, the one Leroi has taken, means pushing back
and declaring race genetic. Given the country's political
economy this second one may indeed be the road many will
choose, a choice for which it is fast becoming apparent
they will be greatly rewarded.
There may be a third path. Biologists and social
scientists can work together under the umbrella of
history. Health outcomes emerge out of layers of
historical processes--some ancient, others more immediate.
While it may jump to mind that evolutionary processes are
the ancient ones, evolution generates novelty daily, as
HIV quasispecies show. Human social processes, on the
other hand, have been operating in one form or another
since the origin of the species, even as they have
undergone fundamental changes across history. So there are
likely interactions occurring across scales of biocultural
organization worth study by researchers of a variety of
disciplines.
In that context social scientists could assimilate the
idea that genes exist and they can have effect on an
individual's pathologies. Biologists, in turn, should come
to terms with public health data that clearly indicate the
means by which to incur the greatest impact on population
health involve altering social circumstances, with
dividends for all. End racist practices, end economic
exploitation, and everybody's health improves. For the
benefit of those who don't believe it we should run the
experiment.
Robert G. Wallace
Department of Biology
City College of New York