Y-chromosomal Aaron

Y-chromosomal Aaron is the name given to the hypothesized most recent common ancestor of many of the patrilineal Jewish priestly caste known as Kohanim (singular "Kohen", "Cohen", or Kohane). In the Torah (known as the Old Testament of the Christian Bible), this ancestor is identified as Aaron, the brother of Moses.

The original scientific research was based on the hypothesis that a majority of present-day Jewish Kohanim share a pattern of values for 6 Y-STR markers, which researchers named the Cohen Modal Haplotype (CMH).

Additional early research using 12 Y-STR markers indicated that about half of contemporary Jewish Kohanim shared Y-chromosomal J1 M267, specifically haplogroup J-P58 (also called J1c3). Other Kohanim groups share a different ancestry, including haplogroup J2a (J-M410).

Molecular phylogenetic research published in 2013 and 2016 for haplogroup J-M267 places the Y-chromosomal Aaron within subhaplogroup Z18271, age estimate 2638-3280 years Before Present (yBP).

Although membership in the Jewish community has, since at least the second century CE, been passed by matrilineal descent according to Orthodox tradition (see: Who is a Jew?), tribal identity, and membership in the group that originally comprised the Jewish priesthood (Cohen or Kohen; plural: Cohanim or Kohanim), has been determined by patrilineal descent. Modern Kohanim claim descent from a biblical person, Aaron, brother of Moses, in the direct lineage from Levi, the patriarch of the Tribe of Levi, great grandson of Abraham, according to the tradition codified in the Tanakh (שמות / Sh'mot/Exodus 6). DNA testing is aiding scholars to trace the lineages found among modern Jewish populations, including contemporary Cohen families, to decipher the origins of the peoples who were joined to the ancient Israelites and to identify genetic admixture and genetic drift.

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