Relatives in the 65th generation
Geneticists have discovered a record-breaking large family of 13 million people
Geneticists have "grown" a record-breaking large family tree, uniting approximately 13 million inhabitants of modern Europe, America, Australia and South Africa, whose common ancestor lived on Earth only 65 generations ago, according to an article published in the journal Science (Kaplanis et al., Quantitative analysis of population-scale family trees with millions of relatives).
"In addition to family ties, we were able to find out how longevity genes affect the life expectancy of their carriers. On average, their carriers live five years longer than other people. It's not as much as it might seem – smoking, for example, takes ten years of life at once," says Yaniv Erlich from Columbia University in New York (USA). In recent years, many portals dedicated to genealogy have appeared on the global network, whose users constantly exchange family genealogical archives to search for new relatives and expand knowledge about their ancestors. Similar studies are carried out by various genetic startups that collect not archives, but the DNA of their clients.
Ehrlich and his colleagues analyzed 86 million genealogical records left by users of one of the largest sites of this kind, and tried to find all their relatives using methods of computational mathematics and genetics.
As Ehrlich notes, his team expected to see family trees uniting thousands and tens of thousands of modern inhabitants of the Earth. To their great surprise, they managed to discover one giant tree, consisting of about 13 million people living in various parts of the World – in the USA, Canada, Britain and other European countries, in South Africa and on the territory of Australia and New Zealand.
Having discovered such an amazing thing, scientists tried to find out when the common ancestor of this entire army of people lived, and tried to uncover the history of the spread of this giant family on Earth by deciphering and comparing the structure of mitochondrial DNA, a small part of the genome transmitted from mother to her children, in some members of this "clan".
As it turned out, their common ancestor lived relatively recently, about 65 generations ago, during the time of Christopher Columbus and other figures of the era of Great Geographical Discoveries, when the inhabitants of Europe began to spread rapidly across all continents of the planet.
© MyHeritage, Columbia University
This genetic analysis, according to Ehrlich, helped his team uncover another unusual detail from the life of Europeans of that time and refute one common notion associated with family traditions.
The fact is that earlier scientists and many ordinary people believed that in the past people more often married and married "their own" and entered into closely related marriages due to the underdevelopment of transport infrastructure and the lack of opportunity to regularly communicate with potential husbands and wives. The situation, according to supporters of this idea, changed in the middle of the 19th century, when the first railways, steamships and telegraphs appeared.
The authors of the article found out that this is not the case. In fact, in the middle of the 19th century, people were more likely to get married and marry cousins, cousins and other relatively close relatives than men and women they didn't know, despite the fact that they had to drive 20-30 kilometers to meet their future wife or husband.
According to geneticists, this suggests that such a choice of second halves was not due to geographical restrictions, but to culture and traditions that disappeared far from immediately after most people had the opportunity to travel long distances.
According to Ehrlich, further analysis of this tree and the genetic data associated with it will help to uncover other secrets from people's lives in the recent and distant past.
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