In article article authored by Kristina Killgrove and published on LIVE SCIENCE
Geographical barriers and cultural differences can prevent people from mingling with their neighbors, leading to genetic isolation — and the phenomenon is more common than most people think.
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Over the past 50,000 years, humans have populated nearly every corner of the globe — and due to geographic barriers, some of these populations then remained isolated for thousands or even tens of thousands of years.
Other populations have become cloistered thanks to insular cultural or religious practices. As a result, the genetic diversity of our species has declined over the past 50 millennia.
Genetic diversity in a given population can be reduced in what is known as a “founder event” — when a small group of people splits off from a larger population, which leads to a smaller gene pool in the isolated group. In a study of 460 populations around the world, roughly half showed evidence of a recent founder event, researchers concluded in 2022.
Here’s a look at some of the most genetically isolated groups of modern humans — and how these isolated populations are helping researchers better understand humans’ unique abilities and diseases that affect some groups more than others.
2. Parsis
Four Parsi women sit by the sea to pray (Image credit: Dinodia Photos / Alamy Stock Photo)
The Parsis are a community of Zoroastrians who migrated to India from Persia in the seventh century. Traditional Parsis disapprove of marriage outside of their religion, which may have led to the group’s isolation.
Geneticists are particularly interested in the longevity of the Parsis, who have gene variants correlated with living well into their 90s, despite the higher-than-average rate of breast cancer in women. A 2021 study published in Meta Gene concluded that the Parsi practice of endogamy — marrying within their group — was likely the reason for these particular traits.