Are Jews more closely related to other Jews around the world, or are they more closely related to their non-Jewish neighbors? What can we learn from recent gene research that will help us answer the century old question: 'are Jews a nation or a religion?'.

A recent genetic analysis focusing on Jews from North Africa, when added to an overall genetic map of Jewish Diasporas studies in the last few years, indicates that both views are somewhat correct because lots of non-Jews converted to Judaism during the centuries of the Roman Empire, and very few non-Jews converted to Judaism in Europe, especially since the Crusades.

The findings, by researchers at Albert Einstein College of Medicine, were published online August 6, 2012 in the Proceedings of the National Academy of Sciences. 

They support the historical record of Middle Eastern Jews, mostly males, settling in North Africa during Classical Antiquity. These men actively proselytizing non-Jews who lived where they settled, and then married into the local populations, a process similar to the way Islam spread in Indonesia. 

By this process, the basic distinct Jewish populations of Jews from the Land of Israel mixed with local converts were formed, that then stayed largely intact for more than 1,500 years. 

Most of those who entered the Jewish community did so during the four to five centuries before Roman laws outlawed conversion to Judaism

In a previous genetic analysis, the researchers showed that modern-day Sephardic (Greek and Turkish), Ashkenazi (Eastern European) and Mizrahi (Iranian, Iraqi and Syrian) Jews from the Middle East, are more related to each other than to their contemporary non-Jewish neighbors, with each group of Jews forming its own cluster within the larger Jewish population. 

Further, each group demonstrated both Middle-Eastern ancestry; and varying percentages of converts to Judaism from the surrounding populations. 

Two of the major Jewish populations -- Middle Eastern Jews and European Jews -- were found to have diverged from each other almost 2,500 years ago.

The current study extends that analysis to North African Jews. Their genetic relatedness to each other, to other Jewish Diaspora groups, and to their non-Jewish North African neighbors had not been well defined in the past. The study also included members of Jewish communities in Ethiopia, Yemen and Georgia. 

DNA signatures found in Ethiopian Jews indicate that they are genetically different from Middle Eastern Jews and also from the other non-Jewish people living in Ethiopia. The genetic evidence is consistent with historical accounts that local people were converted to Judaism in large numbers. The Jewish community then spent more than 2,000 years in cultural and genetic isolation.

Yemenite Jewish people also form a separate genetic group from other Jews, which is consistent with large scale conversion to Judaism in the centuries prior to the advent of Islam.. "I think of it as both the flow of ideas as well as genes that contribute to Jewishness,"" Dr. Ostrer, the lead researcher, says. 

In the Caucasus, Georgian Jews are an offshoot of groups that first moved from Palestine to present-day Iran and Iraq, the new analysis shows.

In all, the researchers analyzed the genetic make-up of 509 Jews from 15 populations along with genetic data on 114 individuals from seven North African non-Jewish populations. 

North African Jews exhibited a high degree of endogamy, or marriage within their own religious group in the last 12-13 centuries, in accordance with Jewish custom. Ethiopian and Yemenite Jewish populations also formed distinctive genetically linked clusters, as did Georgian Jews.

All Jewish groups provided evidence of large numbers of converts to Judaism from the local populations in the distant past, with much smaller numbers of converts to Judaism in the seven to ten centuries prior to the twentieth century.

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Rabbi Allen S. Maller retired after serving for 39 years as Rabbi of Temple Akiba in Culver City, California. His web site is rabbimaller.com.