If you've ever tried to put together your family tree, you'll know that it's often pretty hard to get past your great-grandparents. But thanks to crowd-sourced data gathered from a genealogy website, researchers have managed to piece together a vastly interconnected family tree made up of over 13 million people, telling the story of love, family, and genetics over the past 500 years.
The project is the largest scientifically-backed family tree to date, created using huge banks of data from 86 million public profiles on Geni.com, a privately-owned genealogy and social networking website.
Their findings, published this week in the journal Science, detail how cultural and genetic information has spread across Europe and North American over the last 500 years, around 11 generations.
“All 13 million individuals in the family tree are connected, there is a path, or link, between any two individuals in this tree,” study author Joanna Kaplanis, PhD student at the Wellcome Sanger Institute, told IFLScience.
The interconnected tree shows many wider socio-economic insights that can only be possible using vast banks of information. For one, it’s possible to see the effects of historical events on the family tree, such as elevated death rates at military age during the American Civil War, WWI, and WWII.
They found that most people found a spouse within an average of 10 kilometers (6 miles) of where they were born pre-1750. Between 1800 and 1850, people traveled farther than ever to find a life partner - nearly 19 kilometers (12 miles) on average.
“This change in spousal distance has previously been attributed as the reason why people also started marrying people who were less related to them. Before 1850 the average genetic relatedness of a couple was on the order of 4th cousins,” said Kaplanis.
“However the data in this study shows that there is a 50-year lag before this starts happening and that from 1800 to 1850 individuals continued to marry relatives despite being born further away from their future spouse,” she added. “This suggests that it was probably cultural changes rather than changes in transportation that led to this decrease in relatedness in couples.”
The length of people’s lives is often a debate of nature versus nurture. With all this genetic data at their fingertips, the researchers set out to find the extent of genes' role in a person's longevity. The results indicate that genes can only account for 16 percent of person’s life length. The rest, it appears, is all about nurture and lifestyle. That’s towards the lower end of previous estimates, which tend to range between 15 to 30 percent.
The study authors made their epic dataset available for further academic research via FamiLinx.org. Undoubtedly, this kind of big data genealogical research is here to stay, with a huge potential to provide never-before-seen insights into human history and genetics.