Joshua Lipson: on Jewish genetic genealogy
What has genetics taught us about Jewish history, and what will it teach us?
They review the historical demographics of the Jews of both Northern Europe and the Mediterranean, as well as the possible founding source populations from the Levant (Palestine) and Mesopotamia (Babylon). They discuss the cultural and genetic differences between the Sephardim and Ashkenazim and consider whether the preponderance of evidence suggests a continuity of European Jews with Classical Antiquity or a more recent migration in the early Middle Ages. Josh believes that the recent genetic research indicating a more recent migration is probably wrong and that Y-chromosomal evidence implies Jews were present in the Western Mediterranean 2,000 years ago.
Josh brings a comprehensive understanding of historical, textual, linguistic and onomastic evidence to the table in explaining how dialect differences and family names can be used to tease out distinctions within the Ashkenazim, with clear regional identities in the Rhineland, Galicia (Southwest Poland), and the Baltic already being evident during the Middle Ages. He also argues that there is good evidence Rhineland Jews are subtly different from Central/Eastern European groups who presumably descend from them.
Finally, Razib discusses some of the finer points of genetic testing, statistical inferences, and how genetic models continue to improve over time, as well as where flaws in the testing algorithms might gloss over minute details. These details often provide subtle clues that might offer deeper insight if carefully analyzed by a human expert.