The contemporary Ashkenazi Jewish population, as characterised by several recent genetic studies, is approximately 600 to 800 years old and is probably the result of the fusion of ancestral European and Middle-Eastern populations, according to research published this week in Nature Communications.
These previous studies have described Ashkenazi Jewish individuals as a genetically distinct population, close to other Jewish populations, as well as to present-day Middle-Eastern and European people. As is common in distinct populations, they demonstrate distinctive genetic characteristics including a high prevalence of genetic diseases, such as Parkinson’s disease, and breast and ovarian cancer.
Itsik Pe’er and colleagues report high-depth sequencing of 128 complete genomes of Ashkenazi Jewish individuals and use their results to confirm a previously reported population bottleneck - a severe reduction in population size - which they find occurred 25 to 32 generations ago.
The authors also produced a model that indicates that the formation of the contemporary Ashkenazi Jewish population occurred 600 to 800 years ago (close to the time of the population bottleneck) with the fusion of two ancestral populations: ancestral European and ancestral Middle-Eastern. They also find that the ancestral European population went through a founding bottleneck when diverging from ancestral Middle Easterners 20.4 to 22.1 thousand years ago, around the time of the Last Glacial Maximum. The ancestors of both of these populations underwent another bottleneck, probably corresponding to an Out-of-Africa event.
Aside from insights into the history of European and Middle-Eastern populations, this study may also provide a baseline genome for the Ashkenazi Jewish population, allowing deleterious genetic mutations to be more easily identified.