Mitochondrial Eve is said to be our matrilineal most recent common ancestor. It is estimated that she lived 200,000 years ago in East Africa. All human beings today have descended from this woman through their mother's side. Mitochondrial DNA is passed down from mother to child without recombining, which means every person's mtDNA descended directly from hers. Adam, our patrilineal most recent common ancestor and Eve lived thousands of years apart. This was a quite a discovery because it helps prove the hypothesis that humans originated in Africa and subsequently spread outwards.
