More than just a tool for predicting health, modern genetics is upending long-held assumptions about who we are. A new study by Harvard researchers casts new light on the intermingling and migration of European, Middle Eastern and African and populations since ancient times.
In a paper titled "The History of African Gene Flow into Southern Europeans, Levantines and Jews," published in PLoS Genetics, HMS Associate Professor of Genetics David Reich and his colleagues investigated the proportion of sub-Saharan African ancestry present in various populations in West Eurasia, defined as the geographic area spanning modern Europe and the Middle East. While previous studies have established that such shared ancestry exists, they have not indicated to what degree or how far back the mixing of populations can be traced.
Analyzing publicly available genetic data from 40 populations comprising North Africans, Middle Easterners and Central Asians were doctoral student Priya Moorjani and Alkes Price, an assistant professor in the Program in Molecular and Genetic Epidemiology within the Department of Epidemiology at the Harvard School of Public Health.
Moorjani traced genetic ancestry using a method called rolloff. This platform, developed in the Reich lab, compares the size and composition of stretches of DNA between two human populations as a means of estimating when they mixed. The smaller and more broken up the DNA segments, the older the date of mixture.
Moorjani used the technique to examine the genomes of modern West Eurasian populations to find signatures of Sub-Saharan African ancestry. She did this by looking for chromosomal segments in West Eurasian DNA that closely matched those of Sub-Saharan Africans. By plotting the distribution of these segments and estimating their rate of genetic decay, Reich's lab was able to determine the proportion of African genetic ancestry still present, and to infer approximately when the We
|Contact: David Cameron|
Harvard Medical School