Thirteen million degrees of Kevin Bacon: World’s largest family tree shines light on life span, who marries whom

Researchers have published what may be the validated largest family tree ever: a genealogy database stretching back 5 centuries that links 13 million people related by blood or marriage. The tree has already led to such insights as the link between genes and longevity and why our ancestors married whom they did. And researchers say that’s just a start.

“This study is an impressive and clever use of crowdsourcing data to address a number of interesting scientific questions,” says geneticist Peter Visscher of the University of Queensland in Brisbane, Australia, who was not involved with the work. The tree’s bigger promise, he and others say, could come if it were linked to health information to explore the role of genetics in diseases.

Computational geneticist Yaniv Erlich of Columbia University says he thought up the project 7 years ago, after he got an email from a distant cousin through a website called Geni.com, where people share their family trees. He emailed the company’s chief technology officer, who gave him his blessing to download the site’s tens of millions of public profiles listing a person’s name, sex, date and place of birth, date of death, and immediate relatives (but no DNA information). Figuring out how to make sense of the data, verify relationships, and fix errors took time—his team presented an early version of the tree at a meeting more than 4 years ago—and they later added more data, giving them a starting point of 86 million profiles.

Since posting a preprint online a year ago, the Columbia researchers and collaborators have compared their data to 80,000 Vermont death records with education information—including 1000 people in the Geni.com data—in case people interested in genealogy are wealthier and more educated. They found little evidence of such bias, however.