Family trees are used for research in a wide variety of fields, from genetics to economics.
However, the collection of information, as a rule, is very time-consuming, and the data obtained have very limited geographical coverage.
However, in recent years, a large number of resources have appeared, where people independently build genealogical trees and exchange data with each other. Genetics decided to use one of them for a large-scale study.
Using data that is publicly available, geneticists have built a record-high family tree that includes 13 million people.
As described in the article “Science”, it has united 11 generations living from 1650 to 2000.
A group of American and Israeli scientists led by Joanna Kaplanis from the New York Genomic Center collected user data from Geni.com. A total of 86 million profiles were sampled. Researchers analyzed the relationships between study participants, as well as their geographical proximity to each other.
An analysis of family ties between the study participants showed that women, on average, move more often than men, but at shorter distances, and also that the industrial revolution and great travel opportunities did not lead to an immediate decrease in the number of cousin marriages.
As a result, the Kaplanis team received 5.3 million individual genealogical trees uniting users among themselves. The largest included 13 million people and spanned 11 generations. These were mainly Europeans and their descendants who moved to North America.
When analyzing the data, scientists noticed a natural decrease in life expectancy associated with military conflicts, in particular, during the First and Second World War, as well as during the Civil War in America. By marking the birthplace of children on the map, scientists identified the most significant events in the history of the resettlement of people, such as the arrival of the first colonists on the Mayflower to the territory of the modern state of Massachusetts in 1620 and the foundation of the British colony in Australia in 1788.
The database created by the Elrich group records dates of birth and death, as well as family ties. Scientists were interested in the relationship between consanguinity and longevity; it turned out that heredity accounts for about 16% of the variability of life expectancy in close relatives. The remaining 84% comes from other factors, such as life circumstances and habits. These figures are less than those that scientists expected to deduce, and they say that environmental factors affect human health even more than is commonly believed. Earlier, other large genealogical trees were created to assess the role of hereditary factors in the development of Alzheimer’s disease and cancer.
Previously, sociologists using modeling found that online dating contributes to the growth of inter-racial marriage. In addition, the likelihood of divorce in a society where people meet online is less than in a society where online dating is not common.
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