Human populations have waxed and waned over the millennia, with some cultures exploding and migrating to new areas or new continents, others dropping to such low numbers that their genetic diversity plummeted. In some small populations, inbreeding causes once rare genetic diseases to become common, despite their deleterious effects.
A new analysis of more than 4,000 ancient and contemporary human genomes shows how common such “founder events” were in our history. A founder event is when a small number of ancestral individuals gives rise to a large fraction of the population, often because war, famine or disease drastically reduced the population, but also because of geographic isolation –on islands, for example — or cultural practices, as among Ashkenazi Jews or the Amish.
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“Genomic data is really powerful because it not only tells us about where we come from, it tells us about our history at various different time scales, and you can look at how closely related different individuals are to each other. But also, it tells us about bits of DNA that are functionally important and can cause diseases. So, they become quite important to study from a biomedical perspective.” said Priya Moorjani, senior author, assistant professor of molecular and cell biology, UC Berkeley
