Y-Chromosomal Adam and Mitochondrial Eve weren't married

Science has identified two particular human ancestors, a woman and man. The woman, Mitochondrial Eve, is the mother of all mothers. We inherit certain cellular machinery, called mitochondria, from our mothers, not from our fathers. Mitochondrial Eve lived long ago, and she is the source of the mitochondria in all human cells today. The other ancestor, Y-Chromosomal Adam, is the father of all fathers. The Y-chromosome is what turns a newly conceived mammal into a male instead of the default female body type. Every Y-chromosome in every man across the globe comes from this one forefather.


The use of the traditional names Adam and Eve leads some people to conclude that all humans today derive solely from these two ancestors, a mated pair. This assumption is wrong on two counts. First, Mitochondrial Eve and Y-Chromosomal Adam never knew each other. Second, many other ancestors are also the ancestors of all of us.


Mitochondrial Eve lived around 200,000 years ago. There were plenty of other humans around at that time. Most of them would have their lineages eventually die out, but many of them had lineages that would survive. Most of these ancestors, however, would have mixed lines of mothers and fathers. The mitochondria do not survive a generation of males, so these ancestors saw their mitochondrial lines die out even while their DNA survived. And their DNA survives to this day in our modern nuclei, along with Eve's.


Y-Chromosomal Adam lived maybe 60 to 90 thousand years ago, much more recently than Eve. Highly successful males have far more offspring than highly successful females, so male genes spread faster. That's why Adam's Y chromosomes became universal in less than half the time it took Eve's mitochondria to become universal. Again, there were other ancestors alive at the same time as Adam, but these ancestors would be fathers of mothers or mothers of fathers. Only Adam would be the father of all fathers in unbroken patrilineal descent.


We all derive from Adam and Eve, but they're just two individuals with extraordinary lines of descent, just two out of countless other ancestors.


September 2010