and cultural beliefs—gypsies; the kindred clans of Mennonites, Amish, and Hutterites; and Parsis. But no gene pool has been more crucial for DNA research and the quest to develop medical cures than the Diaspora communities of the Jews.

e number of Jews worldwide is
thought to be about 13– 15 million,
although estimates are hazy because
of the complex notion of Jewish iden-
tity. ere are only a few million
Mizrahim (also known as “Oriental
Jews”)—those descended from Jew-
ish communities in the Middle East.
ere are a few million more Sep-
hardim (from
the Hebrew
word Sefar-
ad, mean-
ing “Spain”),
who trace their
ancestry to Ibe-
ria or North
Africa, the cen-
ter of Diaspora
Jewry until the
medieval Inqui-
sitions. Approxi-

mately 10 million Jews ( 5. 5 million in the United States) are Ashkenazim, a word derived from the Hebrew word for “German,” which suggests recent European roots.

Scientists study group genetic variation because it o ers keys to understanding the origins of diseases—the real focus of human genome research. e fact that scientists now acknowledge group-to-group di erences shouldn’t be seen as resurrecting problematic racial theories. But it does mean we need a vocabulary to discuss human di erences. is is particularly important to Ashkenazi Jews, who are at the center of this debate.

is is prickly stu . A er all, Jews (and other minorities) have paid a heavy price throughout history for being considered a race. “Race” is considered a taboo concept in this politically correct era. But for those of us interested in genetics and revelations that have emerged from Haplotype Map (HapMap) research, it must be addressed.

e notion of race is also embedded in the politics of the Middle East, where one of the key issues is the so-called “right of return”—the belief that Jews have spiritual claim to Israel. A walk through the geopolitical hazard zone known as the Internet unearths a number of websites challenging the premise of the Jewish right of return. ey claim, rightfully, that most Palestinians can trace their ancestry back to ancient Palestine. But many of Israel’s ercest critics also claim, dubiously, that most modern Jews— Ashkenazim—have no ancestral links to ancient Israel.

What are the ancestral origins of Ashkenazi Jews? Using a DNA testing service, I discovered that my own Y-chromosome, which has remained unchanged from generation to generation except for the accumulation of DNA mistakes, is haplogroup R1a. at probably marks me as a descendant of the Khazars, making my male lineage not Semitic but Eurasian.