By amassing the data from an online genealogical website, scientists have recently put together the biggest family tree the world has ever seen.

The map details the lives of roughly 13 million people, going back an average of 11 generations. The numbers are astonishing, but it's what this massive block of family history reveals about our past that's truly impressive.

If you're a bit of an amateur genealogist or have ever been curious about the skeletons in your own family closet, you might have dabbled with an on-line family heritage research tool.

There are plenty of genealogy sites out there, but the researchers chose to study the data gathered by in this instance, due to the particular way it collected information on lifespans.

The team pooled the information from more than 86 million publicly available profiles and evaluated them for any odd details, such as people who were both the parent and a child of another individual.

Just in case the data suffered heavily from certain biases, such as leaning towards particular socioeconomic groups, they also compared a section of the data with details from around 80,000 death certificates held by the Vermont Department of Health.

In the end they had enough reliable data to create 5.3 million family trees, the largest of which was a massive, interwoven garden spanning 13 million individuals who lived between 1650 and 2000.

These vast webs of human history were mostly made up of individuals from Europe and North America, detailing everything from patterns of longevity and intermarriage to migration and genetic relationships.

We've all flicked through the family album and learned about the skeletons in the closet of distant cousins and great aunts. Even these relatively tiny snapshots of human pedigrees can be time-consuming affairs to put together.

Such a huge dataset as this has only been possible thanks to the efforts of so many people devoting hours to a labour of love. And no, we don't just mean the scientists.

"Through the hard work of many genealogists curious about their family history, we crowdsourced an enormous family tree and boom, came up with something unique," says MyHeritage geneticist and computer scientist, Yaniv Erlich.

"We hope that this dataset can be useful to scientists researching a range of other topics."

Already the data has produced some weird and wonderful insights into a small section of the world's population over recent centuries.

For example, women in the demographics covered tended to move around more often than men. But men moved longer distances on average, often ending up in entirely new countries.

Erlich suggested to Ars Technica's Kiona N. Smith that it might have something to do with the economics of the day.

"One potential explanation is that males tend to stay in their home town due to better economic opportunities: maybe a shop that they inherited or land," he says.

Large events such as a war or possibly even economic downturns might see them then travel farther afield, where they settle down again.

Advances in transport technology also coincided with longer migrations, with people born before 1800 tending to find partners within an 8 kilometre (5 mile) radius, compared with an average 19 kilometres (12 miles) by 1850, and a 100 kilometre (62 mile) radius by 1950.

But there was an interesting twist in the data; those who were of marrying age during a peak late-19th century transport boom tended to marry into family more often than their predecessors had.

From 1650 to the start of the 19th century, the average married couple in Europe and North America were fourth cousins.

That average family distance shortened for people born just after 1800 for some reason, possible due to a relaxing of taboos.

The level of detail in the map also allowed the researchers to analyse the degree to which our genes help us live longer.

According to the study's results, genetics contributes just 16 percent of what is necessary to see old age, as opposed to the 25 percent found in other studies.

"That's not a lot," says Erlich.

"Previous studies have shown that smoking takes 10 years off of your life. That means some life choices could matter a lot more than genetics."

Not everybody agrees with the interpretation, with other researchers debating the definitions of longevity and the role big data plays in its study.

Thankfully the massive family tree and all of the researcher's data is publically available for anybody to pick through.

Who knows – maybe in years to come we'll be seeing even bigger trees with roots so deep they'll connect us all. Wouldn't that be something?

This research was published in Science.