Genetics can answer the question in a roundabout way. Human DNA sequences today may shed light on our ancestors because some portions of the human genome change very slowly. One of these is the Y chromosome. Women carry two X chromosomes, while men have one X and one Y. The X and Y cannot exchange DNA like the 22 pairs of non-sex chromosomes in humans or the paired X chromosomes in women. As a result, a man should have a carbon copy of the Y chromosome of his father, grandfather and so on. But sometimes a harmless mutation, a misspelling in the genetic code, occurs. The mutation will be passed on to all the man's male descendants. If millions of men have the same mutation, then they all share a distant paternal ancestor.
Underhill studies pairs of mutations on the Y chromosome in current populations. He combines data about the geographic distribution of the mutations with information about when the mutations arose to trace historical migrations.
While reading a previous paper on Y-chromosome mutations in Science that Underhill co-authored, King thought the geographic distribution of some pairs of mutations paralleled that of Neolithic decorative ceramics. King, a psychiatrist with a PhD in mathematics and a deep interest in art history, called Underhill and suggested they compare the two sets of data.
Critics argue that the contemporary gene pool does not reflect what happened thousands of years ago because people have moved around too much since then. Many also see genetics as an entirely separate line of investigation from archaeological work. Researchers had compared genetic studies to language evolution, but no one had attempted to link genetics and material culture. Underhill agreed to undertake the analysis with King.
The Science paper Underhill co-authored described the Y chromosomes of more than 1,000 men in 25 different Middle Eastern and European geographic regions. They found thPage: 1 2 3 Related biology news :1
Contact: Ruthann Richter
Stanford University Medical Center
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