- GO DEEPER
There is not one gene, trait, or characteristic
that distinguishes all members of one race from all members of
another. We can map any number of traits and none would match
our idea of race. This is because modern humans haven't been around
long enough to evolve into different subspecies and we've always
moved, mated, and mixed our genes. Beneath the skin, we are one
of the most genetically similar of all species.
Lots of animals are divided into subspecies. Why doesn't it
make sense to group humans the same way?
Subspecies are animal groups that are related, can interbreed,
and yet have characteristics that make them distinct from one
another. Two basic ingredients are critical to the development
of separate subspecies: isolation and time. Unlike most animals,
humans are a relatively young species and we are extremely mobile,
so we simply haven't evolved into different subspecies.
The earliest hominids evolved from apes about 5 million years
ago, but modern humans (Homo sapien sapiens) didn't emerge
until 150,000-200,000 years ago in eastern Africa, where we spent
most of our evolution together as a species. Our species first
left Africa only about 50,000-100,000 years ago and quickly spread
across the entire world. All of us are descended from these recent
Many other animal species have been around much longer or they
have shorter life spans, so they've had many more opportunities
to accumulate genetic variants. Penguins, for example, have twice
as much genetic diversity as humans. Fruit flies have 10 times
as much. Even our closest living relative, the chimpanzee, has
been around at least several million years. There's more genetic
diversity within a group of chimps on a single hillside in Gomba
than in the entire human species.
Domesticated animals such as dogs also have a lot of genetic
diversity, but this is mostly due to selective breeding under
controlled conditions. Humans, on the other hand, have always
mixed freely and widely. As a result, we're all mongrels: Eighty-five
percent of all human variation can be found in any local population,
whether they be Kurds, Icelanders, Papua New Guineans, or Mongolians.
Ninety-four percent can be found on any continent.
Animals are also limited by habitat and geographical features
such as rivers and canyons, so it is easy for groups to become
isolated and genetically distinct from one another. Humans, on
the other hand, are much more adaptable and have not been limited
by geography in the same way. Early on, we could ford rivers,
cross canyons, move great distances over a relatively short time,
and modify our environment to fit our needs. We are also extremely
mobile as a species. Even the remotest island tribe in the Pacific
originally came from elsewhere and maintained some contact with
We may think global migration is a recent phenomenon, but it
has characterized most of human history. Whether we're moving
halfway around the world or from one village to another, the passage
of genes takes place under many circumstances, large scale and
small: migration, wars, trade, slave-taking, rape, and exogamous
marriage (marriage with "outsiders").
It takes a long time to accumulate a lot of genetic variation,
because new variants arise only through mutation - copying errors
from one generation to the next. On the other hand, it takes just
a very small amount of migration - one individual in each generation
moving from one village to another and reproducing - to prevent
groups from becoming genetically distinct or isolated. Humans
just haven't evolved into distinct subgroups.
But I can see obvious differences between people - don't those
translate into deeper differences, like propensity for certain
The visual differences we are attuned to don't tell us anything
about what's beneath the skin. This is because human variation
is highly non-concordant. Most traits are influenced by different
genes, so they're inherited independently, not grouped into the
few packages we call races. In other words, the presence of one
trait doesn't guarantee the presence of another. Can you tell
a person's eye color from their height? What about their blood
type from the size of their head? What about subtler things like
a person's ability to play sports or their mathematical skills?
It doesn't make sense to talk about group racial characteristics,
whether external or internal.
Genetic differences do exist between people, but it is more accurate
to speak of ancestry, rather than race, as the root of inherited
diseases or conditions. Not everyone who looks alike or lives
in the same region shares a common ancestry, so using "race" as
a shorthand for ancestry can be misleading. Sickle cell, for example,
often thought of as a "racial" disease afflicting Africans, is
actually a gene that confers resistance to malaria, so it occurs
in areas such as central and western Africa, the Mediterranean,
and Arabia, but not in southern Africa. In medicine, a simplistic
view can lead to misdiagnoses, with fatal consequences. Racial
"profiling" isn't appropriate on the New Jersey Turnpike or in
the doctor's office. As evolutionary biologist Joseph Graves reminds
us, medicine should treat individuals, not groups.
On the other hand, the social reality of race can have biological
effects. Native Americans have the highest rates of diabetes and
African American men die of heart disease five times more often
than white men. But is this a product of biology or social conditions?
How do you measure this relationship or even determine who is
Native American or African American on a genetic level? Access
to medical care, health insurance, and safe living conditions
can certainly affect medical outcomes. So can the stress of racism.
But the reasons aren't innate or genetic.
Believing in race as biology allows us to overlook the social
factors that contribute to inequality. Understanding that race
is socially constructed is the first step in addressing those
factors and giving everyone a fair chance in life.
The Resources section of this Web site contains
a wealth of information about issues related to race. There
you'll find detailed information about books, organizations,
film/videos, and other Web sites. For more about this topic,
search under "human variation," "evolution,"
"genetics" and "biology." Explore the
HUMAN DIVERSITY interactivities in the LEARN MORE section of
this Web site.
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