[From many - one.]

Do I remember correctly that they did trace one male lineage back to a common ancestor living at the time of Moses? Jews named Cohen (or variants)?

[From many - one.]

Answered my own question. Here:

Y-chromosomal Aaron - Wikipedia

http://en.wikipedia.org/wiki/Y-chromosomal_Aaron

Neat stuff.

Ya'd think the CR/IDs would be all over this.

[js1138]

Do I remember correctly that they did trace one male lineage back to a common ancestor living at the time of Moses? Jews named Cohen (or variants)?

I believe there is a population of Jews who are descended from a common ancestor in historical times. I don't know the details, but it would not be surprising in a small population that restricts marriage outside the religion.