Growing up in Greece, Iosif Lazaridis shared his compatriots' appreciation that they lived in "the crossroads of Europe and Asia," past and present.
- By STEPHANIE DUTCHEN
To the east lay Turkey and Armenia, gateways to the Near East and Asia. To the north were the Balkans, leading the way into central Europe.
Lazaridis wondered how people in these regions were related to one another. Who shared long-ago ancestry with whom? How might those forebears have moved around this part of the world and had children with one another throughout millennia? How deeply connected were their modern descendants despite national borders and political conflicts?
Many people moved to Greece from the Balkans after the collapse of the Soviet Union, and many Greeks descend from refugees who came from Turkey in the early 20th century, Lazaridis knew. "Surely these changes that happened as I was growing up and that I heard about from old people were just the tip of the iceberg of what had happened in the centuries before," he said.
The questions simmered at the back of Lazaridis' mind as he moved to California to earn a PhD in information and computer science. They followed him to Boston, where he joined the lab of geneticist David Reich at Harvard Medical School.
There, he and colleagues around the world began to unearth answers through the study of ancient DNA.
Now, Lazaridis is co-first author of a trio of papers, published Aug. 25 in the journal Science, that tell the most complete story yet of ancestry in this pivotal part of the world.
The studies describe 15,000 years of genetic history in what the team has dubbed the Southern Arc: the lands sweeping from southeastern Europe into the Middle East, encompassing more than a dozen countries from Romania and Serbia through Greece and Turkey into Armenia, Azerbaijan, Iran, Lebanon, and Israel.
Featuring the genomes of more than 1,300 ancient people, 727 of them sequenced for the first time, the work represents one of the largest analyses to date of ancient human DNA.
"Often there's an artificial distinction between Europe and Asia that people make," said Lazaridis, research fellow in genetics at HMS who serves as a staff scientist in the Reich lab. "For these studies, we said, we have a bunch of people who are neighbors; let's forget about such preconceptions and try to figure out how they're all related and who moved where across time."
In addition to illuminating shifts in different populations' genetic makeup across the centuries, the analyses provide fresh genetic insights into old mysteries such as the identities of Minoan and Mycenaean peoples and the geographic origin of Indo-European languages.
"This is a major leap forward in the field and a milestone in terms of richness of data from this complex region," said co-senior author Reich, professor of genetics at HMS and professor of human evolutionary biology at Harvard University. "Some very striking stories emerge thanks to the power of ancient DNA in large sample sizes."
No easy feat
The results were made possible by collaboration across borders and specialties. The Reich lab partnered with researchers at the University of Vienna to lead a 206-person team based in more than 30 countries.
"These studies were accomplished through a huge amount of raw human effort," said Lazaridis.
