Did the Genes for Light Skin Colors Evolve in Europe?

A widescale genetic survey has shown that despite common misconceptions, race really is only skin deep. Learn more in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from how Stuff Works High brain
Stuff Lauren Vogel bomb here for ages. Humans have divided
our species into groups based upon skin color. The shade
of one's complexion has been a powerful influence upon human culture,
affecting everything from where we live and how much money
we make, to how much political power we have, and

(00:22):
throughout history, racial divisions based upon skin color have led
to violence and war. That's all persisted because people cling
to the belief that people of different skin colors are
inherently different from one another, even though scientists have been
telling us for years that race is a distinction that
we invent in our minds, that there isn't much actual
difference in the genetic makeup of humans of various hues. Now,

(00:43):
an international team of researchers has published a groundbreaking study
in the journal Science that may demolish the concept of
race as a biological concept once and for all. It
found that genetic variations for lighter skin color neither exists
solely nor originate in European populations, challenges the idea of
using skin color as a racial classification and shows that
skin color may only be skin deep. The scientists examined

(01:06):
the genetic origins of skin color in Africans, who vary
widely in shade, from the dark skin of the Dinka
people in South Sudan to the light complexions of the
sun in South Africa. As an accompanying news story in
the journal Science explains, the team used a light meter
to measure the degree to which more than two thousand
individuals skin reflected light. They also gathered blood samples for

(01:27):
genetic studies. The focus upon Africans was significant because most
studies of the genetic underpinnings of race have been based
upon European subjects, a choice that's provided an incomplete and
perhaps misleading picture. We spoke with the studies corresponding author,
Sarah Tishkoff, who's a genetics and biology professor at the
University of Pennsylvania, via email. She said this is part

(01:49):
of a general bias that exists in human genetic studies,
which focus primarily on European populations. This results in a
bias in our knowledge about genetic factors influencing both normal
variable traits like skin color as well as disease risk. Specifically,
studies that focused only on Europeans missed many of the
genetic variants which we identified as associated with skin color.

(02:09):
This is because there's less genetic and phenotypic I. E.
Skin color variation in that population compared to Africans. Also,
many of the variants identified in Europeans are of recent origin.
Prior to our study, it wasn't recognized that variants associated
with both light and dark skin are common in Africa,
and many are very old. Also, our study shows that

(02:29):
both light and dark skin has been evolving in humans.
Prior to our study, that emphasis has been only on
why light skin is adaptive in Europeans. Our study changes
our understanding of the evolutionary history of variation and skin color.
The scientists identified eight genetic variations in four regions of
the human genome that influenced skin shade. Using genetic information

(02:50):
from nearly one thousand, six hundred people, They examined more
than four million single nucleotide polymorphisms. That is, places where
the familiar DNA code made up of proteins represent by
the letters G, A, T, and C may differ by
only one letter. Those genes turn out to be the
ones that have spread all over the planet, showing that
many of the gene variations that cause light skin color

(03:10):
in Europeans actually originated in Africa. The ubiquitous nature of
skin color genes and their persistence over thousands of years
makes racial divisions seem pretty much meaningless from a biological viewpoint.
Tishkov said, I think that work strengthens what so many
geneticists and sociologists already know that race cannot be defined
based on genetic criteria. There have been many abuses committed

(03:33):
in the past and in the present based on that assumption,
so hopefully this and other studies will help dispel the
notion of genetically defined racial groups due to genetic variants
shared among populations around the world. The new data also
shines a light on human evolution, supporting the notion of
an early history migration of biologically modern humans out of
Africa following the southern coast of Asia into Australo Melanesia,

(03:56):
plus a secondary migration into other regions. Tishkov to build
upon the study and explore other questions that remain about
the genetics of skin color, she said in her email.
We want to better understand the biological mechanisms by which
these variants are impacting skin pigmentation. Our study has implications
for better understanding skin pigmentation disorders and melanoma risk. We're

(04:18):
also looking at the genetic basis of other adaptive traits,
as well as genetic and environmental factors influencing disease risk
in ethnically diverse African populations. Today's episode was written by
Patrick J. Keiger and produced by Tristan McNeil. For more
on this and the lots of other evolutionary topics, visit

(04:39):
our home planet, as to works dot com.