In recent years, comparative DNA studies have shed some partial light on how Jews spread to the four corners of the earth, and the possible connections of the most distant communities in Africa, India, and China to the rest of the Jewish people. Razib Khan, a geneticist, surveys some of these data, and their implications. Take, for instance, the Bene Israel Jews of Western India, who today number about 60,000, most of whom live in Israel. Unlike India’s Baghdadi Jews, whose ancestors came from the Middle East in modern times, the Bene Israel have far murkier origins, even if they are far less mysterious than those of the B’nei Menashe of the northeastern part of the country. Khan writes:
The Bene Israel clearly descend from a fusion of a Near Eastern population and local Indians. Judging by the Judaic practices in the community, and the fact that Bene Israel in genomic analyses yield some fraction of identifiable “Jewish” heritage, that Near Eastern population was surely Jewish. What’s more, the Bene Israel Y chromosomes, their paternal lineages, have a particularly strong Jewish imprint, sharing lineages found among European and Middle Eastern Jews. In contrast, their maternal lineages are overwhelmingly Indian. Overall, on the order of 20 to 30 percent of their total ancestry seems to derive from a Middle Eastern population quite similar to Iraqi and Iranian Jews.
From these questions, Khan turns to broader ones:
[Traditionally], Jews see themselves as descendants of Jacob, and to a great extent, this conviction has been validated, insofar as deep and common Near Eastern ancestry is evident in Jewish groups from Germany to Kerala. But Jewish endogamy has limits, and the assimilation of Gentile women has been commonplace from Europe to Asia and into North Africa. . . . The foremothers of many Jewish populations were clearly converts, just like the biblical Ruth, who told her mother-in-law that “your people will be my people and your God my God.”
And yet the examples of the Jews of India and China hint at the possibility that the unique role of Judaism and the Jewish people in Christianity and Islam may have been an important factor in Ashkenazi and Sephardi persistence and flourishing over the last 3,000 years. . . . If the glittering cultural, artistic, and intellectual achievements that members of the Jewish Diaspora have shared with all humanity are a diamond, created by the vice-like pressure of Christian and Muslim domination, you have to wonder . . . what unique contributions we all lost when less enduring minorities, Jewish or otherwise, were culturally and genetically subsumed into their surrounding societies.