Genetics Of The Jewish People
The history of the Jewish people from Classical Antiquity towards modern day provide a guide to understanding their population genetics. Beginning at the time of the Greek and Roman Empires, close 6 million Jews are thought to have resided in the Roman Empire. In the period immediately preceding the fall of the Second Temple in 70 CE, Jewish populations that adhered to Judaism were located throughout the Roman Empire, and extending into the Arsacid Empire to the east. They are likely to have been the ancestors of the Jewish Diaspora populations; Mizrahi, from Middle East, European Ashkenazi and Sephardic and those of North Africa.
Ashkenazic and Sephardic Jews are two distinct subcultures of Judaism. They are all Jews and share the same basic religious beliefs, but have some variations in culture and practice.
Ashkenazic Jews are the Jews of Germany, France, and Eastern Europe and their descendants. Sephardic Jews are the Jews of Portugal, Spain, North Africa and the Middle East and their descendants, who are usually subdivided into Sephardim, from Spain and Portugal, and Mizrachim, from the Northern Africa and the Middle East.
What is the difference between Sephardic and Ashkenazic?
The beliefs of Sephardic Judaism are basically in accord with Orthodox Judaism, however, Sephardic interpretations of halakha (Jewish Law) are somehow different from the Ashkenazic ones. For example, the holiday of Pesach (Passover): Sephardic Jews may eat corn, rice, beans, and peanuts, while Ashkenazic Jews avoid them.
Historically, Sephardic Jews have had an integration into non-Jewish cultures more than the Ashkenazic Jews. Ashkenazic Judaism flourished in Christian lands, and the tension between them was great, and Jews became isolated from non-Christians, either voluntarily or involuntarily. Sephardic Judaism developed in the Islamic lands, where there were less segregation and oppression. Their thought and culture were influenced strongly by Arabic and Greek science and philosophy.
Jewish Genetic Ancestry
The closest genetic neighbors to most Jewish groups are the Palestinians, Israeli Bedouins, and Druze. In addition, the Southern Europeans, including Cypriots. Their proximity to one another suggests a shared genetic history of related Semitic and non-Semitic ancestors who followed different affiliations of religion and tribe.
Monoallelic genetic markers, Y-chromosomal DNA and mitochondrial DNA, have proven their usefulness in understanding the patrilineal and matrilineal origins of Jewish Diaspora groups. Y-DNA analysis showed that most Diaspora Jews are descended from a smaller group of Middle Eastern men. Seven Y chromosome major branches (E3b, G, J1, J2, Q, R1a1, and R1b) that are prevalent among Ashkenazi Jews. Four of these (E3b, G, J1, J2, and Q) were part of the ancestral gene pool from the Middle East, whereas R1b and certain R1a sub-lineages are from Europe and may have incorporated into the Ashkenazi Jewish population. The presence of European Y-chromosomal lineages is the major difference between Ashkenazi Jews, Middle Eastern and Sephardic Jews.
The most common Ashkenazi Jewish Y chromosomal haplogroups are R1a1 and R1b. R1a1 is very common among Eastern European populations, Russians, Ukrainians, and Sorbs (Slavic speakers in Germany), as well as among certain Central Asian groups. However, it should be noted that a Middle Eastern origin for some R1a1 lineages cannot be ruled out. R1b is the most common Y-chromosome branch of Atlantic Europe. Its occurrence among Ashkenazi Jews may be an indicator of the mixture prior to the Ashkenazi Jewish migration to Eastern Europe or at later time points in certain locales.
Four mitochondrial haplogroups were found to account for >40 % of the total among Ashkenazi Jews, providing evidence for four founder females. These haplogroups form the so-called “star phylogenies”. Some of these founders originated in the Middle East. This origin is akin to the patrilineal mode of origins and the founder numbers and population frequencies vary greatly in the Jewish Diaspora populations.
There are very few founder lineages among the Jews of Eastern European (Azerbaijan, and Georgia), North African Libya, Indian Sub-continent (Mumbai, and India, and Belmonte), and Portugal, and they account for the majority of mitochondrial haplotypes. In all of these populations, a sole founding mother was sufficient to account for at least 40 %. Among the Jews of Tunisia and Cochin (south India), two founding mothers account for 30 % of the mitochondrial genomes. There was no founder effect among the Jews of Bulgaria, Turkey, Morocco, and Ethiopia. They all received large influxes of Jewish refugees following the Spanish Inquisition. By contrast, the Jewish communities from Iran, Iraq, and Yemen demonstrate a degree of diversity observed in other groups. However, none of these populations is quite like the Ashkenazi Jews who possess a large contemporary population base, but few founders.
All of the Jewish populations had mitochondrial genomes of Middle Eastern origin except for the two; Ethiopian mitochondrial genomes which are of African origin and the Bene Israel of Indian origin.
9 Dec 2016 / rarikola / 54
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