These studies showed a very high genetic affinity among present-day Cohanim, indicating that they do have a common paternal ancestor, estimated to have lived some 3,000 years ago.
(See The Cohanim/DNA Connection) The most recent genetic research consists of obtaining DNA samples, and doing laboratory analysis and comparison of the DNA markers on the Y-chromosome –- which is passed from father to son, and on the mt DNA (mitrocondrial DNA) –- which is passed intact from mother to son and daughter.
"Despite their long-term residence in different countries and isolation from one another, most Jewish populations were not significantly different from one another at the genetic level. Nat'l Academy of Science, May 9, 2000) The basis of this new field of population research is the study of the Y-chromosome, which is passed virtually unchanged from father to son.
The results support the hypothesis that the paternal gene pools of Jewish communities from Europe, North Africa and the Middle East descended from a common Middle Eastern ancestral population, and suggest that most Jewish communities have remained relatively isolated from neighboring non-Jewish communities during and after the Diaspora." (M. The rare mutations -– which are changes in the non-coding portion of its DNA –- can serve as markers, which can distinguish peoples.
These linguists see Yiddish grammar as fundamentally Slavonic, with modern Yiddish developed by incorporating large numbers of German and Hebrew words into the context of a basically Slavic grammar and syntax.
The Ashkenazi paternal gene pool does not appear to be similar to that of present-day Turkish speakers.
This finding opposes the suggestion that Ashkenazim are descended from the Kuzars, a Turkish-Asian empire that converted to Judaism en masse in or about the 8th century CE.
This argument parallels the controversy over the origin and development of Yiddish -– the language of Eastern European Jews.
One theory proposes that Jews, migrating from the Rhineland and neighboring regions spoke an old form of German which provided the basis of Yiddish.