Y-chromosomal Adam

In human genetics, Y-chromosomal Adam (Y-mrca) is the patrilineal human most recent common ancestor (mrca) from whom all Y chromosomes in living men are descended. Y-chromosomal Adam is thus the male counterpart of Mitochondrial Eve (the mt-mrca), the matrilinear human most recent common ancestor, from whom all mitochondrial DNA in living humans is descended.

Time frame
Y-chromosomal Adam probably lived between 60,000 and 90,000 years ago, judging from molecular clock and genetic marker studies. While their descendants certainly became close intimates, Y-chromosomal Adam and mitochondrial Eve are separated by at least 30,000 years, or many hundred generations.

The more recent age of the Y-mrca compared to the mt-mrca corresponds to a larger statistical dispersion of the probability distribution for a Paleolithic man to have living descendants compared to that of a Paleolithic woman. While fertile women had more or less equally distributed chances of giving birth to a certain number of fertile descendants, chances for fertile men varied more widely, with some fathering no children and others fathering many, with multiple women.

Y-chromosomal Adam is not the same individual at all points in human history; the Y-mrca of all humans alive today is different from the one for humans alive at some point in the remote past or future: as male lines die out, a more recent individual becomes the new Y-mrca. In times of rapid population growth, patrilinear lines are less likely to die out than during a population bottleneck.

Naming
Y-chromosomal Adam is named after the "Adam" of the Genesis creation story as a metaphor only, and is not considered to be the first human.

The name incorrectly implies that Y-chromosomal Adam was the only living male of his time; he was not. Many men alive at the same time as Y-chromosomal Adam have descendants alive today. However, only Y-chromosomal Adam produced an unbroken line of male descendants carrying his Y chromosome (Y-DNA) that persists today.