— All over the world, millions of people see skin color as a
symbol of superiority or inferiority, whether they are
conscious of it or not.
see humanity’s array of skin tones, from white to ocher to
black, as a positive mark of our remarkable diversity.
Jablonski sees skin color, first and foremost, as an
evolutionary gateway to vitamin D.
the Evan Pugh professor of anthropology at Penn State
University, has made a name for herself with her research on
how human skin color evolved from the earliest humans to today’s
multiple hues. The short version: Our skin color is primarily
designed to regulate how much sunlight we let into our bodies
to produce vitamin D, which is important for bone health, safe
pregnancies and a strong immune system. In a related way, it
also keeps too much ultraviolet radiation from destroying
folate in women’s bodies, which can lead to certain birth
general, she has found, the skin color of ancient people
matched up well with the amount of sunlight that bathed the
regions in which they settled. Those in the tropics had darker
skin; those in temperate zones had lighter skin. That worked
fine for the thousands of years when people spent most of
their time living and working outdoors, she said.
two things happened. First, modern technology allowed people
to settle all over the world, creating mismatches between skin
color and sunlight.
got people from England moving to Australia; people from West
Africa moving to Finland. You have this dramatic movement of
people to environments to which they are poorly adapted from a
modern development, urbanization, means people are spending
more and more time indoors.
health perspective, these trends have had a bigger effect on
darker-skinned people, she said. Lighter-skinned people can
adapt to sunny climates by using sunscreen to prevent skin
cancer and folate problems and yet still get enough of the
ultraviolet B radiation that triggers vitamin D production.
you’re a darkly pigmented person living in a far northern
place or living in a city and not getting much sun exposure,
though, then we are not addressing the problem of likely
vitamin D deficiency," Jablonski said.
Bodnar, a researcher at the University of Pittsburgh’s
Graduate School of Public Health, has found this trend in her
studies of pregnant women.
who has a doctorate in nutrition, has found that women who
have vitamin D deficiencies are more likely to deliver babies
early or get the dangerous condition of preeclampsia, which
causes a woman’s blood pressure to spike and often leads to
premature delivery of her child.
using the most conservative guidelines of how much vitamin D
women should have, Bodnar said, nearly half of
African-American mothers have vitamin D deficiencies, compared
with just 10 percent of Caucasian mothers.
to this picture is a study Jablonski and colleagues in South
Africa have been conducting among residents of Cape Town.
darker-skinned South Africans, she said, the more time they
spend indoors, the lower their vitamin D levels, and the
weaker their immune systems.
news, she said, is that vitamin D supplements can reverse
began her career studying fossils of primates and how they
evolved into the first humans.
wasn’t particularly focused on skin color until a colleague
asked her to give a public presentation on the topic and she
had to delve into the issue more deeply.
is the subject she is best known for, including a TED Talk
video that has been viewed nearly 740,000 times.
early humans first began to walk upright, she said in an
interview at her offices at Penn State, "they spent a lot
of their time running away from predators," which meant
they needed to find a way to efficiently dissipate body heat.
They did that by shedding their fur and using sweat to help
cool their bodies, she said. This, in turn, exposed them to
the intense sunlight of the African savanna.
first, she said, early humans would have had white skin.
"But when our skin became functionally naked, we had to
deal with this hot sun. Hair is an excellent sunscreen. If you
get rid of most of your body hair, you have to compensate.
This is when we see the evolution of permanent dark
pigmentation in the human lineage."
earliest humans emerged around 2 million years ago, she said.
By 1.2 million years ago, they had become uniformly
before that, though, some early humans had left Africa for
less sunny climates in Europe and Asia. To get enough vitamin
D, their skin needed to become lighter so more ultraviolet
radiation would penetrate their bodies.
some places, those changes are relatively recent.
research by Iain Mathieson at Harvard University, revealed at
a recent meeting of the American Association of Physical
Anthropologists, showed that early hunter-gatherers in what
are now Spain, Hungary and Luxembourg still had dark skin
8,500 years ago, according to Science magazine. Eight-hundred
years later, one group in southern Sweden already had genes
that coded for lighter skin, and then, farmers from the Near
East who had lighter complexions moved into Europe, began
intermarrying, and quickly spread genes for paler skin.
cases, Jablonski said, an ethnic group’s skin color has
changed more than once as it migrated.
example are the forebears of Native Americans, who would have
started out with lighter skin in northern Asia but became
darker after moving to North and Central America. "In the
last 15,000 years," she said, "they moved into high
ultraviolet conditions, and we see increasing tanning
abilities — different genes being turned on to deal with
increased solar intensity."
why the whole idea of racial categories makes no sense to her.
a particular skin color has evolved two, three or five times
independently, that classification you’ve just created is a
bunch of nonsense. That skin color doesn’t appear
exclusively in a certain group, so it is terribly misleading
to use skin color to partition people into groups."
research for her 2012 book, "Living Color: The Biological
and Social Meaning of Skin Color," she learned that the
preference for lighter skin evolved for two different reasons
agricultural societies, where most people were darker skinned,
"if you were of higher status, you could afford to spend
time indoors and your relatively lighter skin would be an
indication of your higher socioeconomic status."
when European nations became more powerful, their explorers
went to Africa and other tropical areas looking for cheap
labor, "and they were astonished by the darkness of the
people." Using allusions in the Bible to light as a
symbol of good and darkness as a symbol of evil, she said,
"that became part of their justification for treating
darker people with a less than human status … and this was
the beginning of heinous racial prejudice and the
justification for slavery."
Rediker, a Pitt historian who has written extensively about
the slave trade, said that in some ways, slavery actually
created the idea of white and black races.
African slave trade accelerated in the 1700s, the slave ship
crews often were a motley collection of Europeans, Africans,
Americans and others, and yet "when they got to the
shores of Africa, all of those sailors were known as the ‘white
people,’ even the ones of African descent." In a
similar way, Africans from many different tribes were thrown
together onto slave ships, "and when they were unloaded
on the other side of the Atlantic, they were members of the
illustrates, he said, "how race is fundamentally
connected to issues of social and economic power. I think what’s
happening now is people are challenging that coupling."
is saddened by the way these racial classifications have
don’t use mid-18th-century directional implements in my car;
I have a GPS. Why are we following guidelines created by
18th-century thinkers who had their own personal, emotional
biases? It is illogical and just plain stupid for us to
persist in these categories."