Abstract
Author SummaryFew of us know our family histories more than a few generations back. It is therefore easy to overlook the fact that we are all distant cousins, related to one another via a vast network of relationships. Here we use genome-wide data from European individuals to investigate these relationships over the past 3,000 years, by looking for long stretches of genome that are shared between pairs of individuals through their inheritance from common genetic ancestors. We quantify this ubiquitous recent common ancestry, showing for instance that even pairs of individuals from opposite ends of Europe share hundreds of genetic common ancestors over this time period. Despite this degree of commonality, there are also striking regional differences. Southeastern Europeans, for example, share large numbers of common ancestors that date roughly to the era of the Slavic and Hunnic expansions around 1,500 years ago, while most common ancestors that Italians share with other populations lived longer than 2,500 years ago. The study of long stretches of shared genetic material promises to uncover rich information about many aspects of recent population history.
Highlights
Even seemingly unrelated humans are distant cousins to each other, as all members of a species are related to each other through a vastly ramified family tree
We use genome-wide data from European individuals to investigate these relationships over the past 3,000 years, by looking for long stretches of genome that are shared between pairs of individuals through their inheritance from common genetic ancestors
We applied the fastIBD method, implemented in BEAGLE v3.3 [31], to the European subset of the Population Reference Sample (POPRES) dataset, which includes language and country-of-origin data for several thousand Europeans genotyped at 500,000 single nucleotide polymorphism (SNP)
Summary
Even seemingly unrelated humans are distant cousins to each other, as all members of a species are related to each other through a vastly ramified family tree (their pedigree). Population genetics has studied the distant bulk of these genetic relationships, which in humans typically date from hundreds of thousands of years ago (e.g., [1,2]). Such studies have provided deep insights into the origins of modern humans (e.g., [3]), and into recent admixture between diverged populations (e.g., [4,5]). Most such genetic relationships among individuals are very old, some individuals are related on far shorter time scales. We investigate such patterns of recent relatedness in a large European dataset
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