A week or two ago I ran across a news item from Scientific American about how genetic differences between ethnic groups are probably accounted for by differences in gene expression in genes that are shared across ethnic groups, as well as by large-scale DNA differences between ethnic groups. The differences in gene expression are likely due to non-coding regions of DNA near the gene in question, which regulate the expression of the gene. One reason this is important is that it can help researchers figure out the genetic differences that lie behind different ethnic groups’ vulnerabilities to different diseases. In this particular study, researchers compared Asian and European populations.
My impression has been that genetic differences between ethnic groups are real, although there is no single marker that places people into discrete genetic groups, and that some diseases and conditions appear more frequently in one ethnic group than another (e.g., cystic fibrosis usually occurs in Caucasians, hypertension is more common among African-Americans than in other groups, and type 2 diabetes is more prevalent in Latin American and African populations). This news story from January 2005 describes a study at Stanford a few years ago that looked at the racial categories people used to identify themselves and found that those categories mapped very well to categories that could be identified genetically. Out of 3,636 people in the study, only 5 of them placed themselves in a category that did not match the ethnic group their DNA put them in.
I’m fascinated by population genetics, and what we can learn from our DNA about where we come from and how we got to be who we are. And from a practical standpoint, it can be useful to understand the origins of diseases that strike one ethnic group more than another, and in particular to figure out how to prevent these diseases. See, for example, Gary Paul Nabhan’s Why Some Like It Hot: Food, Genes, and Cultural Diversity, in which he investigates differences in food preferences and health between various ethnic groups. I think he has a chapter in there on the Tohono O’odham people of southwestern North America and why they are so much more prone to obesity and diabetes when they eat the standard US high-calorie, high-carb, high-fat diet (not that it’s good for anyone), and how they can change their eating and exercise habits to reduce their risk of the disease.
So I was surprised to read the other day that race is a entirely a social construct, and that “there is no gene for race”. This was in some information I received about the Human Race Machine, which visited the Indiana University campus in Bloomington this past week. The machine scans people’s faces and then applies morphing algorithms to make them resemble faces from other races (I think you can choose from five or six: Caucasian, African, Indian, Middle Eastern, Asian, maybe another that I can’t remember). The experience is intended to help people realize the essential unity of the human race, despite superficial differences in skin color and facial features. How you get from there to the idea that the differences are not real and are not linked to any underlying physical cause is beyond me, and I’m extremely disheartened that someone evidently thinks that we can’t get across the message that race-based discrimination and hatred are wrong without tossing science aside to do it.
Obviously people have used racial differences as an excuse to rank populations in a hierarchy, to claim that one race (their own, of course) is superior to the rest and that members of other races are somehow not as human and do not need to be accorded the same rights, dignity, and freedom. That, of course, is purely wrong, but it’s not wrong because we’re really all genetically or physically identical. And genetic differences between races don’t negate the essential similarity of human needs and human rights across different populations.
Maybe as part of the maturation of our species we need to learn that genetic differences (which are statistically small but by no means trivial) are not about superiority or inferiority; instead, they tell our history and describe the entire spectrum of humankind on this planet. Race is not entirely a social construct; the hatred and ranking and subhuman status accorded to some races over the course of history are socially constructs. I would like to think we can attack those wrongs without jettisoning the science that’s teaching us about human diversity, the ways our bodies work and why they sometimes don’t. I remember a line from the original Star Trek series, from some discussion about the Vulcan ideal of IDIC (infinite diversity in infinite combinations). Spock said something about the way our differences can combine to create meaning and beauty. Isn’t that the essence of diversity? And don’t we have to acknowledge that the differences are real in order to truly value diversity?
Interesting point, Mary! I agree it’s not smart to throw science out to prove a point. As an aside it would interesting to find out if there’s any research relating the Indian (the real ones!) population’s genes/markers/etc. and how prone they are to acid refulx and other digestive conditions. When I started having problems with acidity and refulx, one of the things I thought about was the fact that I started eating so many things my digestive system was not used to (carbonated beverages, cheese, black beans, etc.). It would be interesting to see how much of my problems were because of unusual exposure and how much of it was genetically pre-disposed! -Arvind
very interesting Arvind. some diseases are triggered by lifestyle/culture/eating habits.
It is true that different ethnic groups/races tend to favor certain foods over others.
Indigenous Japanese have very high rates of stomach cancer, much higher than other groups. Which could be linked to their high consumption of raw fish/sushi–and uncooked fish is know to have parasites– Could that be the reason for their high rates of stomach cancer? (the volcanic ash theory sounds kind of sketchy.)
African-Americans prone to hypertension and diabetes are also prone to eating diets high in fat which can lead to various diseases. Could we be culturally pre-disposed to certain diseases based on diet rather than
(and) genetics? And that diseases occur along ethnic lines because certain ethnicities tend to eat similar foods or have similar lifestyles/cultures? Surely it’s not completely genetic. The food is the culprit sometimes.
That’s a good point. (I didn’t know that about the Japanese–interesting.) I think interactions between food and genes are probably part of it. Diet can certainly change genetics (given enough time, of course). For example, lactose tolerance in adulthood is a genetic difference that evolved in populations with access to dairy products (i.e., in places where the climate allows milk to be stored safely, so adults who could digest milk could take advantage of the protein and other nutrients it contains).
I think at least part of the story with the Tohono O’odham people in the southwest is that they evolved in an environment with seasonal scarcity. It made sense for their bodies to store fat well because they’d need it during the periodic lean times. But they’re not adapted to perpetual abundance; their genes were shaped by interactions with a different environment.