The Human Family Tree

"The most detailed human family tree so far available is one constructed over many years by Dr. Douglas C. Wallace and his colleagues at the Emory University School of Medicine in Atlanta. Dr. Wallace's tree is based on mitochondrial DNA, tiny rings of genetic material that are bequeathed only by the egg cell and thus through the maternal line. A counterpart tree for men, based on analysis of the Y chromosome, has been prepared by Dr. Peter A. Underhill and Dr. Peter J. Oefner of Stanford University.

Mitochondria, which live inside human cells but outside the nucleus, escape the shuffling of genes that occurs between generations and are passed unchanged from mother to children. In principle, all people should have the same string of DNA letters in their mitochondria.

Population geneticists believe that the ancestral human population was very small -- a mere 2,000 breeding individuals, according to a calculation published last December. But the family tree based on human mitochondrial DNA does not trace back to the thousand women in this ancestral population. The tree is rooted in a single individual, the mitochondrial Eve, because all the other lineages fell extinct.

The same is true of the Y chromosome tree, a consequence of the fact that in each generation some men will have no children, or only daughters, so the number of different Y chromosomes may steadily diminish, even if the population stays the same size.

This ancestral human population lived somewhere in Africa, geneticists believe, and started to split up some time after 144,000 years ago, give or take 10,000 years, the inferred time at which both the mitochondrial and Y chromosome trees make their first branches."

Article Source: http://ow.ly/nODuE

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We are one. Separation is an illusion even science has the backing.  Jocelyn