A Moment of Science

Tracing Our Ancestors

Now that scientists have mapped the human genome, or genetic blueprint, and are analyzing the results, you may be wondering if they’ll find a genetic basis for race. For example, can you determine whether a person is Norwegian or Nigerian based on his or her DNA?

Although DNA can be used to identify traits like eye color, tracing these traits beyond a person’s immediate family can be complicated. First, in order to trace traits back to a certain group, you have to look at several genes at once–that’s because we inherit some genes from each parent. Also, since humans are about 99.9 percent similar genetically, there are just as many differences within a population group as there are between different groups.

Another challenge is continuous gene mutation. Even if you determine that two people have blue eyes, it may not be clear whether they inherited the genes for blue eyes from a common ancestor, or if the gene arose independently in two different population groups.

Despite these difficulties, once scientists understand the genome, they should be able to use DNA to identify the geographic origin and reconstruct ancestral migration patterns of individuals who aren’t recent descendants of intermarriage. However, given globalization and our increasingly mobile society, this kind of analysis probably won’t be meaningful for long.

Of course, using DNA to identify race raises many difficult ethical questions. After all, in the past, pseudo-scientific racial divisions provided justification for atrocities like slavery and the Holocaust. As with all scientific research, the question here isn’t just what can be learned, but also what use will be made of this knowledge.

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