Genomic Data Reveal a Complex Making of Humans

Ancestry proportions by grandparental country of origin. For individuals from the Jewish-Israeli sample with four grandparents from the same country and for the Ethiopian-Jewish sample, proportions of ancestry for individuals from a given geographic point are shown as segments of each pie chart.

Middle Eastern ancestry may be a common factor among Jewish populations; however, the majority of Jewish populations have been located outside of the Middle East for up to 2000 years. As is the case with other highly mobile human populations there has been historically documented gene flow between Jewish populations and local host populations. In addition, because these are populations defined, in part, by religion, gene flow into Jewish populations is a product of conversion as well as marriage. Thus, there should be genetic admixture in Jewish subpopulations that reflects, in part, their migratory histories and may contribute to current genetic differences among Jewish populations. It is known that detecting and quantifying recent admixture is dependent on the time since divergence of the putative parental populations as well as the number and information content of markers. Because clustering algorithms are also dependent on the relative differences between populations, the context of a sample in a given analysis (i.e., the extent of its difference from samples of other populations included in the analysis) can affect clustering patterns. This aspect of the process of population substructure detection may be overlooked in case control association studies and may affect results if not taken into consideration. Based on this, we hypothesized that the presence or absence of putative parental populations in a STRUCTURE analysis would affect the ability to detect substructure in Jewish populations and differences between Jewish populations.

The migratory history and origins of Ashkenazi Jews are less clear than those of non-Ashkenazi Jews. During the early Middle Ages in Europe, Jews lived in close proximity with their non-Jewish neighbors in small villages with constant interaction. Intermarriage, although periodically outlawed by host-country governments, occurred with some regularity [53]. In addition, Jewish Europe was never solely inhabited by Ashkenazi Jews. Some Jews expelled from Spain during the inquisition settled in part of the Ottoman Empire, which includes the Balkans (present-day Turkey, Bulgaria, Greece, Bosnia, and Serbia), while others went to Italy, Holland, and France [54]. In fact, all subjects in this study who identified their grandparents as having come from Balkan countries also identified themselves as non-Ashkenazi and those with two grandparents from Balkan countries identified the parent on that side as non-Ashkenazi.

We believe that the apparent Southern genetic component of those of European descent (Jewish or not), as well as that seen in Jews, is actually originally Middle Eastern in origin. This is consistent to various degrees with previous results from y-chromosomal [3,8], mtDNA [3,5,21] and autosomal evidence [25,26] as well as historical evidence. The large Northern component in all Ashkenazi populations included in this study indicates significant local contribution to these populations, which either occurred early in their histories (German and Ukraine) or in small increments over time (other Ashkenazi populations as evidenced by high variance of Northern/Southern components). Among non-Ashkenazi Jewish populations sampled, although all have exhibited porous membership, Ethiopian and Indian Jewish communities have particularly significant local contributions to their gene pools.

BMC Genetics | Full text | Identification of population substructure among Jews using STR markers and dependence on reference populations included


Haplotypes constructed from Y-chromosome markers were used to trace the paternal origins of the Jewish Diaspora. A set of 18 biallelic polymorphisms was genotyped in 1,371 males from 29 populations, including 7 Jewish (Ashkenazi, Roman, North African, Kurdish, Near Eastern, Yemenite, and Ethiopian) and 16 non-Jewish groups from similar geographic locations. The Jewish populations were characterized by a diverse set of 13 haplotypes that were also present in non-Jewish populations from Africa, Asia, and Europe. A series of analyses was performed to address whether modern Jewish Y-chromosome diversity derives mainly from a common Middle Eastern source population or from admixture with neighboring non-Jewish populations during and after the Diaspora. Despite their long-term residence in different countries and isolation from one another, most Jewish populations were not significantly different from one another at the genetic level. Admixture estimates suggested low levels of European Y-chromosome gene flow into Ashkenazi and Roman Jewish communities. A multidimensional scaling plot placed six of the seven Jewish populations in a relatively tight cluster that was interspersed with Middle Eastern non-Jewish populations, including Palestinians and Syrians. Pairwise differentiation tests further indicated that these Jewish and Middle Eastern non-Jewish populations were not statistically different. The results support the hypothesis that the paternal gene pools of Jewish communities from Europe, North Africa, and the Middle East descended from a common Middle Eastern ancestral population, and suggest that most Jewish communities have remained relatively isolated from neighboring non-Jewish communities during and after the Diaspora.

Jewish religion and culture can be traced back to Semitic tribes that lived in the Middle East approximately 4,000 years ago. The Babylonian exile in 586 B.C. marked the beginning of major dispersals of Jewish populations from the Middle East and the development of various Jewish communities outside of present-day Israel (1). Today, Jews belong to several communities that can be classified according to the location where each community developed. Among others, these include the Middle Eastern communities of former Babylonia and Palestine, the Jewish communities of North Africa and the Mediterranean Basin, and Ashkenazi communities of central and eastern Europe. The history of the Jewish Diaspora—the numerous migrations of Jewish populations and their subsequent residence in various countries in Europe, North Africa, and West Asia—has resulted in a complex set of genetic relationships among Jewish populations and their non-Jewish neighbors. Several studies have attempted to describe these genetic relationships and to unravel the numerous evolutionary factors that have come into play during the Diaspora (2–11). Some of the key arguments in the literature concern the relative contributions of common ancestry, genetic drift, natural selection, and admixture leading to the observed similarities and differences among Jewish and non-Jewish communities.

Given the complex history of migration, can Jews be traced to a single Middle Eastern ancestry, or are present-day Jewish communities more closely related to non-Jewish populations from the same geographic area? Some genetic studies suggest that Jewish populations show substantial non-Jewish admixture and the occurrence of mass conversion of non-Jews to Judaism (2, 3, 10, 12). In contrast, other research points to considerably greater genetic similarity among Jewish communities with only slight gene flow from their respective host populations (5, 7, 9, 11, 13). Furthermore, it has been demonstrated that the degree of genetic similarity among Jewish communities and between Jewish and non-Jewish populations depends on the particular locus that is being investigated (4, 8, 11). This observation raises the possibility that variation associated with a given locus has been influenced by natural selection.

Jewish and Middle Eastern non-Jewish populations share a common pool of Y-chromosome biallelic haplotypes

king This is the most comprehensive survey of genetic diversity in Native Americans to date, and the first to account for recent non-Native admixture. Our analyses show that the great majority of Native American populations—from Canada to the southern tip of Chile—derive their ancestry from a homogeneous “First American” ancestral population, presumably the one that crossed the Bering Strait more than 15,000 years ago. We also document at least two additional streams of Asian gene flow into America, allowing us to reject the view that all present-day Native Americans stem from a single migration wave, consistent with more complex scenarios proposed by other studies. In particular, the three distinct Asian lineages we detect: "First American", "Eskimo-Aleut," and a separate one in the Na-Dene speaking Chipewyan, are consistent with a three wave model proposed by Greenberg, Turner and Zegura based mostly on dental morphology and a controversial interpretation of the linguistic data. However, our analyses also document extensive admixture between First Americans and the subsequent streams of Asian migrants, which was not predicted by the model of Greenberg and colleagues, such that Eskimo-Aleut speakers and the Chipewyan derive more than half their ancestry from First Americans. Further insights into Native American history will benefit from the application of analyses similar to those performed here to whole genome sequences and to data from the many admixed populations in the Americas that do not self-identify as Native.

www.ncbi.nlm.nih.gov/pmc/articles/PMC3615710/