May 8, 2013
It’s In The Genes: Europeans Have Been One Big Family For Past Thousand Years
Lawrence LeBlond for redOrbit.com - Your Universe Online
If there is one thing you can say about families, it is the larger the better. And by looking at genetic data of people from Ireland to the Balkans, researchers have found that Europeans are one big family, and have been for the past thousand years.
Graham Coop, a professor of evolution and ecology at UCDavis, and Peter Ralph, a professor at University of Southern California (USC), published a recent study of the genetics of Europeans in the May 7 issue of the journal PLOS Biology.
The duo set out to study the relatedness among Europeans over the past 3,000 years. Using information from the Population Reference Sample (POPRES) database, Coop and Ralph compared genetic sequences of more than 2,000 individuals. They found that the degree of genetic relatedness, as expected, was smaller the farther apart people live from one another. However, even if two individuals lived 2,000 miles apart, the researchers found they would likely be related to all of one another´s ancestors from a thousand years ago.
"What's remarkable about this is how closely everyone is related to each other. On a genealogical level, everyone in Europe traces back to nearly the same set of ancestors only a thousand years ago," Coop said in a statement. “This was predicted in theory over a decade ago, and we now have concrete evidence from DNA data.”
The duo also found subtle regional variations in the underlying kinship of Europeans. Barriers such as mountain ranges and linguistic differences have slightly reduced relatedness in some regions. Coop noted, however, that these are relatively small differences.
By just going back a few thousand years, it can be shown through genetics that everyone in Europe is related to everyone else. "The overall picture is that everybody is related, and we are looking at only subtle differences between regions," said Coop.
To learn more about the patterns of relatedness, Coop and Ralph researched ideas about the expected amount of genome shared between relatives of varying degrees of relatedness. For example, first cousins share long stretches of DNA due to the fact they share the same grandparents. Looking farther back, the team researched shorter blocks of DNA that were shared between cousins separated by many more generations.
With each new generation, the number of ancestors doubles. This makes the chance of having identical DNA in common with more distant relatives even less likely. But in large samples, the duo still found rare cases of shared DNA. Through further analysis, they were able to detect these shared blocks of DNA in individuals spread out across Europe, and were also able to calculate how long ago they shared an ancestor.
Coop and Ralph said their findings may change the way most Europeans view their neighbors across a continent that has long been struggling with conflict.
“The basic idea that we´re all related much more recently than one might think has been around for a while, but it is not widely appreciated, and still quite surprising to many people, even scientists working in population genetics, including ourselves,” they duo said in an email to The Associated Press. “The fact that we share all our ancestors from a time period where we recognize various ethnic identities also points at how we are like a family – we have our differences, but are all closely related.”
The duo hopes to continue their work with larger groups of people by researching more detailed databases. But while DNA can tell a lot about the history of a people, Coop noted that other examples, such as archaeology and linguistics, can provide much more information about how cultures and societies move and change.
"These studies need to proceed hand in hand, to form a much fuller picture of history," Coop said.
Ralph said genetic research such as theirs has helped in distinguishing the recent history of African Americans. He also said the technique could prove useful in studying other living creatures, such as the humpback whale.
“A survey of humpback whale DNA could shed light on population sizes in the pre-whaling era, for instance, or the genes of a particular kind of tree might tell scientists something about how that species has responded to glaciation in the past,” said Ralph, according to Eryn Brown of the Los Angeles Times.
As for humans, Coop said that the close kinship found in Europeans likely exists in other areas of the world as well.