Tracing Our Ancestors

Rick Kittles discussed the complexities of African-American ancestry and connected African-Americans’ increasing interest in genealogy to the group’s lost identity from slavery. I had expected him to talk more about his cancer research and medical applications for genetic sequencing, but the lecture focussed almost entirely on social issues and how understanding of race has changed with a better knowledge of genetics. For example, Kittles explained how he had always thought that he was 100% black because his skin is relatively dark, but when he had his DNA analyzed he discovered that he had a significant amount of genetic variation that is unique to Europeans. It just happened that his chromosome 15, which houses most of the genes responsible for skin color, had all African alleles.

Kittles showed a graph that plotted Chicago residents’ actual percentage of white and black ancestry along a single horizontal axis, and each dot was colored red or blue according to whether the person self-reported as white or black. Towards the middle, where genetic breakdowns were near 50/50, there was a jumble of colors; some self-reported whites were more black than self-reported blacks, and some self-reported blacks were more white than self-reported whites. Kittles used this to show that the way most people categorize race is still incredibly primitive– everyone just judges by appearances, despite the proven inaccuracy of that strategy. There is a lot of variation within groups, and identity is largely dependent on how you were raised. As another example of classification that doesn’t fit with genetics, Kittles talked about how people in both Mexico and Puerto Rico identify as Hispanic. Although most Mexicans are a blend of indigenous and European heritage while most Puerto Ricans are a blend of West African and European heritage, they lump themselves in the same ethnic group because they all speak Spanish.

It was impossible to leave this lecture and not want to see your own genetic breakdown by ethnicity. However, I wish he had spent more time discussing the implications of the fact that a number of people in the audience probably went home, paid $99, and did just that with a click of the mouse. Are we moving towards more precise descriptions of race, or will people who appear white or black still identify that way even if genetically they are more of the other? Will improved ability to understand a patient’s ancestry help doctors recognize risk of genetic diseases? As more people begin to discover their mixed heritage, what will that do to ethnic identity? Kittles’ main messages seemed to be 1) race is a lot more complicated than you think and 2) using genetics to trace your heritage is really fun. These are good things to be aware of, but I would have appreciated more detailed explanations of the science involved as well as a better discussion of future possibilities.

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