London
— Shortly after last
year's tsunami
devastated the lands on
the Indian Ocean, The
Times of India ran an
article with this
headline: "Tsunami
May Have Rendered
Threatened Tribes
Extinct." The
tribes in question were
the Onge, Jarawa, Great
Andamanese and
Sentinelese - all living
on the Andaman Islands -
and they numbered some
400 people in all. The
article, noting that
several of the
archipelago's islands
were low-lying, in the
direct path of the wave,
and that casualties were
expected to be high,
said, "Some beads
may have just gone
missing from the Emerald
Necklace of India."
The
metaphor is as colorful
as it is well
intentioned. But what
exactly does it mean?
After all, in a
catastrophe that cost
more than 150,000 lives,
why should the survival
of a few hundred tribal
people have any special
claim on our attention?
There are several
possible answers to this
question. The people of
the Andamans have a
unique way of life.
True, their material
culture does not extend
beyond a few simple
tools, and their visual
art is confined to a few
geometrical motifs, but
they are
hunter-gatherers and so
a rarity in the modern
world. Linguists, too,
find them interesting
since they collectively
speak three languages
seemingly unrelated to
any others. But the
Times of India took a
slightly different tack.
These tribes are
special, it said,
because they are of
"Negrito racial
stocks" that are
"remnants of the
oldest human populations
of Asia and
Australia."
It's
an old-fashioned, even
Victorian, sentiment.
Who speaks of
"racial
stocks" anymore?
After all, to do so
would be to speak of
something that many
scientists and scholars
say does not exist. If
modern anthropologists
mention the concept of
race, it is invariably
only to warn against and
dismiss it. Likewise
many geneticists.
"Race is social
concept, not a
scientific one,"
according to Dr. Craig
Venter - and he should
know, since he was first
to sequence the human
genome. The idea that
human races are only
social constructs has
been the consensus for
at least 30 years.
But
now, perhaps, that is
about to change. Last
fall, the prestigious
journal Nature Genetics
devoted a large
supplement to the
question of whether
human races exist and,
if so, what they mean.
The journal did this in
part because various
American health agencies
are making race an
important part of their
policies to best protect
the public - often over
the protests of
scientists. In the
supplement, some two
dozen geneticists
offered their views.
Beneath the jargon,
cautious phrases and
academic courtesies, one
thing was clear: the
consensus about social
constructs was
unraveling. Some even
argued that, looked at
the right way, genetic
data show that races
clearly do exist.
The
dominance of the social
construct theory can be
traced to a 1972 article
by Dr. Richard Lewontin,
a Harvard geneticist,
who wrote that most
human genetic variation
can be found within any
given "race."
If one looked at genes
rather than faces, he
claimed, the difference
between an African and a
European would be
scarcely greater than
the difference between
any two Europeans. A few
years later he wrote
that the continued
popularity of race as an
idea was an
"indication of the
power of
socioeconomically based
ideology over the
supposed objectivity of
knowledge." Most
scientists are
thoughtful,
liberal-minded and
socially aware people.
It was just what they
wanted to hear.
Three
decades later, it seems
that Dr. Lewontin's
facts were correct, and
have been abundantly
confirmed by ever better
techniques of detecting
genetic variety. His
reasoning, however, was
wrong. His error was an
elementary one, but such
was the appeal of his
argument that it was
only a couple of years
ago that a Cambridge
University statistician,
A. W. F. Edwards, put
his finger on it.
The
error is easily
illustrated. If one were
asked to judge the
ancestry of 100 New
Yorkers, one could look
at the color of their
skin. That would do much
to single out the
Europeans, but little to
distinguish the
Senegalese from the
Solomon Islanders. The
same is true for any
other feature of our
bodies. The shapes of
our eyes, noses and
skulls; the color of our
eyes and our hair; the
heaviness, height and
hairiness of our bodies
are all, individually,
poor guides to ancestry.
But
this is not true when
the features are taken
together. Certain skin
colors tend to go with
certain kinds of eyes,
noses, skulls and
bodies. When we glance
at a stranger's face we
use those associations
to infer what continent,
or even what country, he
or his ancestors came
from - and we usually
get it right. To put it
more abstractly, human
physical variation is
correlated; and
correlations contain
information.
Genetic
variants that aren't
written on our faces,
but that can be detected
only in the genome, show
similar correlations. It
is these correlations
that Dr. Lewontin seems
to have ignored. In
essence, he looked at
one gene at a time and
failed to see races. But
if many - a few hundred
- variable genes are
considered
simultaneously, then it
is very easy to do so.
Indeed, a 2002 study by
scientists at the
University of Southern
California and Stanford
showed that if a sample
of people from around
the world are sorted by
computer into five
groups on the basis of
genetic similarity, the
groups that emerge are
native to Europe, East
Asia, Africa, America
and Australasia - more
or less the major races
of traditional
anthropology.
One of
the minor pleasures of
this discovery is a new
kind of genealogy. Today
it is easy to find out
where your ancestors
came from - or even when
they came, as with so
many of us, from several
different places. If you
want to know what
fraction of your genes
are African, European or
East Asian, all it takes
is a mouth swab, a
postage stamp and $400 -
though prices will
certainly fall.
Yet
there is nothing very
fundamental about the
concept of the major
continental races;
they're just the easiest
way to divide things up.
Study enough genes in
enough people and one
could sort the world's
population into 10, 100,
perhaps 1,000 groups,
each located somewhere
on the map. This has not
yet been done with any
precision, but it will
be. Soon it may be
possible to identify
your ancestors not
merely as African or
European, but Ibo or
Yoruba, perhaps even
Celt or Castilian, or
all of the above.
The
identification of racial
origins is not a search
for purity. The human
species is irredeemably
promiscuous. We have
always seduced or
coerced our neighbors
even when they have a
foreign look about them
and we don't understand
a word. If Hispanics,
for example, are
composed of a recent and
evolving blend of
European, American
Indian and African
genes, then the Uighurs
of Central Asia can be
seen as a 3,000-year-old
mix of West European and
East Asian genes. Even
homogenous groups like
native Swedes bear the
genetic imprint of
successive nameless
migrations.
Some
critics believe that
these ambiguities render
the very notion of race
worthless. I disagree.
The physical topography
of our world cannot be
accurately described in
words. To navigate it,
you need a map with
elevations, contour
lines and reference
grids. But it is hard to
talk in numbers, and so
we give the world's more
prominent features - the
mountain ranges and
plateaus and plains -
names. We do so despite
the inherent ambiguity
of words. The Pennines
of northern England are
about one-tenth as high
and long as the
Himalayas, yet both are
intelligibly described
as mountain ranges.
So,
too, it is with the
genetic topography of
our species. The billion
or so of the world's
people of largely
European descent have a
set of genetic variants
in common that are
collectively rare in
everyone else; they are
a race. At a smaller
scale, three million
Basques do as well; so
they are a race as well.
Race is merely a
shorthand that enables
us to speak sensibly,
though with no great
precision, about genetic
rather than cultural or
political differences.
But it
is a shorthand that
seems to be needed. One
of the more painful
spectacles of modern
science is that of human
geneticists piously
disavowing the existence
of races even as they
investigate the genetic
relationships between
"ethnic
groups." Given the
problematic, even
vicious, history of the
word "race,"
the use of euphemisms is
understandable. But it
hardly aids
understanding, for the
term "ethnic
group" conflates
all the possible ways in
which people differ from
each other.
Indeed,
the recognition that
races are real should
have several benefits.
To begin with, it would
remove the disjunction
in which the government
and public alike
defiantly embrace
categories that many,
perhaps most, scholars
and scientists say do
not exist.
Second,
the recognition of race
may improve medical
care. Different races
are prone to different
diseases. The risk that
an African-American man
will be afflicted with
hypertensive heart
disease or prostate
cancer is nearly three
times greater than that
for a European-American
man. On the other hand,
the former's risk of
multiple sclerosis is
only half as great. Such
differences could be due
to socioeconomic
factors. Even so,
geneticists have started
searching for racial
differences in the
frequencies of genetic
variants that cause
diseases. They seem to
be finding them.
Race
can also affect
treatment.
African-Americans
respond poorly to some
of the main drugs used
to treat heart
conditions - notably
beta blockers and
angiotensin-converting
enzyme inhibitors.
Pharmaceutical
corporations are paying
attention. Many new
drugs now come labeled
with warnings that they
may not work in some
ethnic or racial groups.
Here, as so often, the
mere prospect of
litigation has
concentrated minds.
Such
differences are, of
course, just differences
in average. Everyone
agrees that race is a
crude way of predicting
who gets some disease or
responds to some
treatment. Ideally, we
would all have our
genomes sequenced before
swallowing so much as an
aspirin. Yet until that
is technically feasible,
we can expect racial
classifications to play
an increasing part in
health care.
The
argument for the
importance of race,
however, does not rest
purely on utilitarian
grounds. There is also
an aesthetic factor. We
are a physically
variable species. Yet
for all the triumphs of
modern genetics, we know
next to nothing about
what makes us so. We do
not know why some people
have prominent rather
than flat noses, round
rather than pointed
skulls, wide rather than
narrow faces, straight
rather than curly hair.
We do not know what
makes blue eyes blue.
One
way to find out would be
to study people of mixed
race ancestry. In part,
this is because racial
differences in looks are
the most striking that
we see. But there is
also a more subtle
technical reason. When
geneticists map genes,
they rely on the fact
that they can follow our
ancestors' chromosomes
as they get passed from
one generation to the
next, dividing and
mixing in unpredictable
combinations. That, it
turns out, is much
easier to do in people
whose ancestors came
from very different
places.
The
technique is called
admixture mapping.
Developed to find the
genes responsible for
racial differences in
inherited disease, it is
only just moving from
theory to application.
But through it, we may
be able to write the
genetic recipe for the
fair hair of a
Norwegian, the
black-verging-on-purple
skin of a Solomon
Islander, the flat face
of an Inuit, and the
curved eyelid of a Han
Chinese. We shall no
longer gawp ignorantly
at the gallery; we shall
be able to name the
painters.
There
is a final reason race
matters. It gives us
reason - if there were
not reason enough
already - to value and
protect some of the
world's most obscure and
marginalized people.
When the Times of India
article referred to the
Andaman Islanders as
being of ancient Negrito
racial stock, the
terminology was correct.
Negrito is the name
given by anthropologists
to a people who once
lived throughout
Southeast Asia. They are
very small, very dark,
and have peppercorn
hair. They look like
African pygmies who have
wandered away from
Congo's jungles to take
up life on a tropical
isle. But they are not.
The
latest genetic data
suggest that the
Negritos are descended
from the first modern
humans to have invaded
Asia, some 100,000 years
ago. In time they were
overrun or absorbed by
waves of Neolithic
agriculturalists, and
later nearly wiped out
by British, Spanish and
Indian colonialists. Now
they are confined to the
Malay Peninsula, a few
islands in the
Philippines and the
Andamans.
Happily,
most of the Andamans'
Negritos seem to have
survived December's
tsunami. The fate of one
tribe, the Sentinelese,
remains uncertain, but
an Indian coast guard
helicopter sent to check
up on them came under
bow and arrow attack,
which is heartening.
Even so, Negrito
populations, wherever
they are, are so small,
isolated and
impoverished that it
seems certain that they
will eventually
disappear.
Yet
even after they have
gone, the genetic
variants that defined
the Negritos will
remain, albeit
scattered, in the people
who inhabit the littoral
of the Bay of Bengal and
the South China Sea.
They will remain visible
in the unusually dark
skin of some
Indonesians, the
unusually curly hair of
some Sri Lankans, the
unusually slight frames
of some Filipinos. But
the unique combination
of genes that makes the
Negritos so distinctive,
and that took tens of
thousands of years to
evolve, will have
disappeared. A human
race will have gone
extinct, and the human
species will be the
poorer for it.
Armand
Marie Leroi, an
evolutionary
developmental biologist
at Imperial College in
London, is the author of
"Mutants: On
Genetic Variety and the
Human Body."