Category: Race


There is a gene, with the exciting name of Tp53, that, among other things, regulates apostosis (programmed cell death). Apostosis is actually good for a number of reasons, but one thing that it does is get rid of damaged cells before they cause problems. There are, however, two variants of this gene: one has the amino acid arganine, in which apostosis proceeds normally, and the other, which has the amino acid proline, where apostosis is curtailed. The arganine variant has been shown to protect individuals from the development and spread of cancer cells. This is a good thing, of course. However, apostosis of brain cells occurs in the aftermath of a stroke, and if it is not checked, this can delay or prevent an individual’s recovery. You can imagine, then, that a new study finds that people with the arginine variant do not recover as well from strokes as those with the proline variant. From a summary in ScienceNews:

Of people who had a poor prognosis after a stroke, about 81 percent carried two copies of the arginine variant. About 91.5 percent of people with a poor outcome after a hemorrhage had the arginine variant. None of the people with two copies of the proline variant had bad outcomes after either stroke or hemorrhage. People with one copy of each variant tended to have good prognosis after either type of brain injury.

One commentator suggests that his may not apply equally well across racial groups. Again, from the summary:

“We know already that there’s no way this is going to hold up in African Americans,” says Maureen Murphy, a cancer biologist at the Fox Chase Cancer Center in Philadelphia. African Americans tend to have the proline version of p53, but also have high rates of stroke, often with very poor outcomes, she says. It will be important to repeat the study in other ethnic groups to determine the variants are good predictors of stroke outcome for everyone.

References

Gomez-Sanchez, J.C., et al. (2011). The human Tp53 Arg72Pro polymorphism explains different functional prognosis in stroke. Journal of Experimental Medicine. 209: online.

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Smithsonian Magazine has a fascinating interview with Daniel Sharfstein about his book, “The Invisible Line: Three American Families and the Secret Journey from Black to White.” His book shows just how fluid the idea of race could be, even in the American South, which was pretty rigid about the concept, particularly during the 17th and 18th centuries. There’s lots of interesting discourse here, so you should check it out, but here are a couple of things worth quoting:

Q: You note that an early 18th-century governor of South Carolina granted the Gibsons, who clearly had African-American ancestry, permission to stay in his colony because “they are not Negroes nor Slaves.” How did the governor reach such a nebulous conclusion?

Sharfstein: It shows how fluid understandings of race can be. The Gibsons were descended from some of the first free people of color in Virginia, and like many people of color in the early 18th century they left Virginia and moved to North Carolina and then to South Carolina, where there was more available land and the conditions of the frontier made it friendlier to people of color. But when they arrived in South Carolina there was a lot of anxiety about the presence of this large mixed-race family. And it seems that the governor determined that they were skilled tradesmen, that they had owned land in North Carolina and in Virginia and—I think most important—that they owned slaves. So wealth and privilege trumped race. What really mattered is that the Gibsons were planters.

Q: One of your subjects, Stephen Wall, crossed from black to white to black to white again, in the early 20th century. How common was that crossing back and forth?

Sharfstein: My sense is that this happened fairly often. There were many stories of people who, for example, were white at work and black at home. There were plenty of examples of people who moved away from their families to become white and for one reason or another decided to come home. Stephen Wall is interesting in part because at work he was always known as African-American, but eventually, at home everyone thought he was Irish.

Q: As you look at the United States now, would you say the color line is disappearing, or even has disappeared?

Sharfstein: I think the idea that race is blood-borne and grounded in science still has a tremendous amount of power about how we think about ourselves. Even as we understand how much racial categories were really just a function of social pressures and political pressures and economic pressures, we still can easily think about race as a function of swabbing our cheek, looking at our DNA and seeing if we have some percentage of African DNA. I think that race has remained a potent dividing line and political tool, even in what we think of as a post-racial era. What my book really works to do is help us realize just how literally we are all related.

Dr. Alondra Nelson, one of the panelists for our event, was recently interviewed by Radio Boston in connection with the opening of the exhibit RACE: Are We So Different? at the Museum of Science in Boston. The exhibit has been touring the US since 2007 and will be at the Durham Museum of Life and Science from October 8, 2011 through January 22, 2012.  This exhibit is an outgrowth of the American Anthropological Association’s RACE Project, which provides an integrated look at the history, biology, and culture of the race concept. A couple of interesting points are made both by Dr. Nelson and Dr. Alan Goodman (Hampshire College and past president of the AAA):

1. Darwinian evolution, with its focus on change over time, is antithetical to the popular, modern conception of “race,” which is all about sorting people into 2, 3, 4, 5 (or whatever) unchanging types.

2.  Modern genetics has shown us that modern humans are, on average, about 99.9% genetically identical. There is a lot of interesting and important information that can be revealed in that 0.1% difference, such as ancestry, geography, or adaptation. But, what is fascinating is that many people choose to focus only on that 0.1% difference to the near exclusion of that 99.9% similarity.   

3. As a species, we are pretty good at categorizing things (can you imagine how difficult it would be to negotiate the world without that ability?). What we tend to do with human categorization, however, is to mesh those categories with the creation and upkeep of power relations between different groups (be it by “race,” ethnicity, socio-economic status, or some combination of these). People in power, of course, do not want to relinquish that power and so, in order to legitimize their relationships with other groups, they often resort to biology (something that is presumably unchangeable) rather than human institutions (which are presumably changeable).

4. The rise of DNA ancestry tests have, in many ways, complicated how people think about who they are and where they come from. Dr. Nelson notes that when a DNA ancestry test does not match up with how an individual construes their own social identity, the scientific tests often do not transform the way an individual thinks about themself. 

5. Science does not exist in a vacuum. Just like anyone else, scientists can bring their own social, historical, and political biases to the lab.

For more on this issue, see Dr. Nelson’s video interview on the Race in the age of genomics post on the blog.

A team of researchers have scanned genes that are known to impact hair color and found that analyzing an individual’s DNA can predict their hair color with a high degree of accuracy. There are upwards of a dozen or so genes that may contribute to hair color in some way, and mutations that change a single nucleotide (Single Nucleotide Polymorphisms, or SNPs) in a gene are largely responsible for color and shade differences. From a summary in Wired Science:

To see if hair color could be predicted using 45 SNPs from 13 genes, Kayser and his team sampled DNA from 385 Polish volunteers and had dermatologists record their hair color. Their testing singled out 13 SNPs on 11 genes that could predict red and black hair colors with about 90 percent accuracy, as well as blond and brown colors with better than 80 percent accuracy.

As if you needed another excuse not to leave your DNA at a crime scene…

One of the genes examined in this study was MC1R, mutations in which have been linked specifically to red hair. Interestingly, the red hair genotype has been identified in some Neandertal individuals (although the specific mutation is different from that seen among modern humans). 

References

Branicki, W., Liu, F., van Duijn, K., Draus-Barini, J., Pośpiech, E., Walsh, S., Kupiec, T., Wojas-Pelc, A., Kayser, M. (2011). Model-based prediction of human hair color using DNA variants. Human Genetics.

Lalueza-Fox, C., Römpler, H., Caramelli, D., Stäubert, C., Catalano, G., Hughes, D., Rohland, N., Pilli, E., Longo, L., Condemi, S., de la Rasilla, M., Fortea, J., Rosas, A., Stoneking, M., Schöneberg, T., Bertranpetit, J., Hofreiter, M. (2007). A melanocortin 1 receptor allele suggests varying pigmentation among Neanderthals. Science 318: 1453-1455. 

Here is an interesting video conversation with Alondra Nelson, one of our panelists for this year’s event, about how people construct their racial identity in the age of genomics.