Y-chromosomal Aaron is the name given to the hypothesized most recent common ancestor of the patrilineal Jewish priestly caste known as Kohanim (singular "Kohen", also spelled "Cohen"). According to the traditional understanding of the Hebrew Bible, this ancestor was Aaron, the brother of Moses.
While some early genetic studies were seen as possibly supporting the traditional biblical narrative, this view was subsequently challenged with some researchers arguing that the genetic evidence "refutes the idea of a single founder for Jewish Cohanim who lived in Biblical times."[1][2] However, recent studies have provided further support for the model of descent from a common ancestor who lived in the First Temple period by demonstrating that Kohanim from different Jewish communities form a "tight cluster" which is "specific to the Jewish Cohens".[3][4]
The original scientific research was based on the hypothesis that a majority of present-day Jewish Kohanim share a pattern of values for six Y-STR markers, which researchers named the extended Cohen Modal Haplotype (CMH).[5] Subsequent research using twelve Y-STR markers indicated that nearly half of contemporary Jewish Kohanim shared Y-chromosomal J1 M267 (specifically haplogroup J-P58, also called J1c3), while other Kohanim share a different ancestry, such as haplogroup J2a (J-M410).[6] The latest studies using single nucleotide polymorphic markers have further narrowed the results down to a single sub-branch known as J1-B877 (also known as J1-Z18271).[3][4]
This finding generated considerable excitement, because it was taken as evidence of the fidelity of an oral tradition extending over millennia... it has been discovered this Y-chromosomal set of markers is not unique to Jewish men... this record refutes the idea of a single founder for Jewish Cohanim who lived in Biblical times... Y-chromosomal analysis of Levites has demonstrated multiple origins that depend on the Diaspora community from which they came—they are not all the descendants of tribal founder Levi.
In conclusion... the overall substantial polyphyletism as well as their systematic occurrence in non-Jewish groups highlights the lack of support for using them either as markers of Jewish ancestry or Biblical tales.
Remarkably, the five Ashkenazi Cohen samples formed the tight cluster J1b-B877, shared only with one Yemenite, one Bulgarian and one Moroccan Cohen coalescing ~2,570 ybp (Table 1).
Another sub-branch—J1a1a1a1a1a1a2-B877—is specific to the Jewish Cohens [...] Its TMRCA of ~ 3.2 kya (95% HPD = 2.4–4.0 kya) overlaps with the previous estimate.
Hammer2009
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