The Genetics of Prehistoric Migration

Over the past three decades fascinating and exciting work has been done mapping the movement of prehistoric peoples through their genetic legacies. The most common method involves the use of the DNA in cell structures called mitochondria. This DNA is referred to as mtDNA (mitochondrial DNA). MtDNA has certain advantages for this kind of historical detective work. First, it can only be inherited from the mother, thus allowing genetic historians to follow a single family tree. Second, mtDNA mutates much faster than regular DNA, allowing us to trace changes over shorter periods of time. The logic behind this work is simple: the closer two populations may be, the fewer the differences in their mutations. We can use this simple chain of variance to trace how groups “split” from a main locus and proceed on to other parts of the world. Based on the number of mutations, we can even approximately date when such divisions occurred.

This method has given very strong support to the idea that modern humans evolved somewhere in East Africa roughly 200,000 years ago and slowly migrated across the globe. This is the first and arguably the most dramatic example of globalization. As humans, we globalized the planet by establishing connections through intra-species contact. To the extent that we are all n-th cousins n-1 times removed, the world really is a single place!

A second method used recently uses mutations on the Y or male chromosome. Scientists have used mutations in the Y chromosome (following the same logic described above) and have overlaid these with archeological data of different pottery styles. The correlation between the two has further supported this new way of studying globalization.

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