But the ancient Iranian DNA was dramatically different from that of the western Anatolian farmers. The two groups of farmers, who lived about 2000 kilometers and 2000 years apart, must have descended from completely different groups of hunter-gatherers who separated 46,000 to 77,000 years ago, Burger says.
A similar genetic disjunction appears in a study led by Harvard University’s David Reich and posted on bioRxiv. This study analyzed ancient DNA from 44 Middle Easterners who lived 14,000 to 3400 years ago, including Natufian hunter-gatherers in Israel, Zagros farmers, and Bronze Age pastoralists in the Eurasian steppe, and compared it with that of 2864 living and ancient people from around the world. By sequencing 1.2 million nucleotides from across each genome, the team found that early farmers of Israel and Jordan (known as the Levant) were genetically distinct from those in the Zagros Mountains, and that both populations were distinct from the western Anatolians who later spread their genes throughout Europe.
The third study, also published on bioRxiv, reported the same stark differences. That study analyzed the complete genome of a 10,000-year-old woman from Ganj Dareh, a site in the Zagros Mountains with the world’s oldest evidence of goat herding.
Burger and Reich also each used their data to peer even further back in time, to the ancestors of the Zagros Mountain farmers. They found that the Zagros people descend from a group of basal Eurasians who separated from the ancestors of all other people outside of Africa 50,000 to 60,000 years ago—before other non-Africans interbred with Neandertals. So the Zagros Mountain farmers had less Neandertal DNA than the western Anatolian farmers, whose ancestors must have branched off later.
The descendants of these early farmers went separate ways. Whereas the western Anatolians later migrated to Europe, Reich’s team proposes that the ancient farmers of the Levant migrated to East Africa, where living people carry some of their distinct DNA, and the Zagros Mountain farmers spread north into the Eurasian steppe and east into South Asia.
