Is Everyone In the World Related?
(Lansing State Journal, October 15, 1997)

When someone makes a claim of being related to another, it is reasonable to expect some type of proof. For instance I can say that I am related to my cousin, and I can prove this by showing that we share one set of grandparents.  This method of proving relatedness by identifying common ancestors tends to break down as we look up our family tree. In general, the knowledge of the members of our extended families doesn't extend very far.  How many of us could name all eight of our great-grandparents, or trace all of their descendants? Looking back even further, our ancestry becomes increasingly blurry and complex until putting a name on even one of the thousands of people involved in our heritage becomes difficult, and tracing all their descendants becomes impossible.

Scientists have ways of establishing relatedness when the direct tracing of family trees breaks down. One recently developed method uses patterns found in DNA to identify populations which share a common ancestry. DNA is the hereditary material, and it holds within it a record of our evolutionary history. DNA patterns are passed down from one generation to the next, thus people who share a particular DNA pattern can say with confidence that they are in fact related, even though they are unable to put a name or face on a common ancestor. When this method was applied to the entire human population (by randomly sampling diverse populations), it confirmed what was already inferred from fossil studies - that everyone in the world is indeed related.

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