NEW YORK – A handful of new genetic studies is providing a clearer look at the ancient populations that lived, met, and moved through the Near East, particularly during the Neolithic period, Bronze Age, and Iron Age.
For the first of these, researchers from the Max Planck Institute for the Science of Human History and other centers around the world used shotgun sequencing and targeted capture sequencing to profile some 1.24 million nuclear SNPs, mitochondrial sequences, and Y chromosome patterns in a total of 110 ancient individuals in Anatolia, the Northern Levant, and the Southern Caucasus. The samples, estimated to be around 3,000 to 7,500 years old, were from sites in present-day Turkey, Azerbaijan, and Syria.
That study, published in Cell on Thursday, revealed some of the population changes that accompanied cultural shifts from the Neolithic Period to the Bronze Age, roughly corresponding to cultural changes that saw pastoralists replace some farming cultures and the advent of societies with defined states.
"Within this geographic scope, you have a number of distinct populations, distinct ideological groups that are interacting quite a lot, and it hasn't really been clear to what degree people are actually moving or if this is simply just a high-contact area from trade," co-senior author Christina Warinner, an archaeogenetics and anthropology researcher affiliated with the Max Planck Institute for the Science of Human History and Harvard University, said in a statement.
"[R]ather than this period being characterized by dramatic migrations or conquest," Warinner explained, "what we see is the slow mixing of different populations, the slow mixing of ideas, and it's percolating out of this melting pot that we see the rise of urbanism — the rise of cities."
After quality control steps, she and her colleagues were left with genome-wide data for 94 of the ancient individuals, including 77 who were directly radiocarbon dated. In analyses that included sequence data for hundreds more ancient individuals profiled in the past, they saw evidence for apparent spread of individuals between Anatolia and the Southern Caucasus region toward the end of the Neolithic Period, leading to populations with gradients of Anatolian and Caucasus ancestry in this region.
More abrupt and complex transitions appear to have taken place in areas of the Northern Levant that now make up parts of Turkey and Syria, according to the team's analyses, particularly leading up to the Bronze Age. The investigators speculated that population changes may reflect migrations out of ancient Mesopotamia that were described in prior geological and archeological studies.
Notably, one of the ancient individuals profiled — a woman whose remains were found in a well in southern Turkey — had Bronze Age ancestry that resembled that in Central Asia, suggesting she or her recent ancestors traveled or were transported over a long distance.
"We can't exactly know her story, but we can piece together a lot of information that suggests that either she or her ancestors were fairly recent migrants from Central Asia," Warinner said. "We don't know the context in which they arrived in the Eastern Mediterranean but this is a period of increasing connectivity in this part of the world."
For a related Cell study, an international team led by investigators in the US, Israel, and Austria focused on populations moving in and around the Southern Levant in the Bronze Age, using new targeted sequence data for 71 Middle to Late Bronze Age individuals and two Iron Age individuals from five archeological sites in northern or central Israel and central Jordan. They analyzed their genome sequences alongside 20 more Bronze or Iron Age individuals from additional sites in the Southern Levant that had been studied in the past.
In this area — which spans what is now Israel, Jordan, Palestinian territories, Lebanon, and a southwestern portion of Syria — the researchers identified a genetically-defined population with ancestry from local Neolithic populations and more recent populations from Iran and the Caucasus that appeared to correspond to the "Canaanites" described in religious texts.
"Individuals from all sites are highly genetically similar, albeit with subtle differences, showing that the archaeologically and historically defined 'Canaanites' correspond to a demographically coherent group," co-senior author Liran Carmel, a geneticist at the Hebrew University of Jerusalem, said in a statement.
Representation of Chalcolithic Iranian and Bronze Age Caucasus ancestry appeared to rise in the Canaanite population with time, the team reported, followed by a series of other population movements into and out of the region.
"[W]e observe evidence for the movement of people over long periods of time from the northeast of the Ancient Near East, including modern Georgia, Armenia, and Azerbaijan, into the Southern Levant region," Carmel explained.
The researchers also saw genetic ties between the populations present in the Southern Levant during the Bronze Age and some populations currently found in the region, with Bronze Age and Chalcolithic Zagros populations contributing around half of the ancestry observed in some Jewish groups and groups from Levantine Arabic-speaking populations. Even so, they noted that "present-day groups also show ancestries that cannot be modeled by the available ancient DNA data, highlighting the importance of additional major genetic effects on the region since the Bronze Age."
In an accompanying perspectives article in Cell, Ludovic Orlando, a molecular anthropologist and geogenetics researcher affiliated with the University of Toulouse and the University of Copenhagen, emphasized that "populations, thus ancestries, are not static through space and time, and no modern groups can be depicted as descending from unique ancestors who once inhabited a single region."
For a third paper, published Thursday in the American Journal of Human Genetics, an international team led by investigators in the UK and Lebanon looked at the population history of Beirut, using genome sequences of 19 individuals, across four time periods in the past 4,000 years, analyzing the sequences in combination with those from thousands of other modern and ancient individuals from prior studies.
"[W]e present new whole-genome sequence data from ancient individuals who lived in the Near East between the Iron Age and the Roman period, spanning a time marked by major historical events and population movements," senior author Chris Tyler-Smith, a researcher at the Wellcome Sanger Institute, and his colleagues wrote.
Although the area was rife with cultural changes that reflected long stretches of outside rule from Egypt, Persia, Greece, and other parts of the world, the investigators explained, results from their study highlighted just a few lasting genetic shifts in the area. Moreover, they suggested that the vast majority of the ancestry found in Lebanon today can be traced back to populations found there during the Bronze Age.
"We see that people like the Egyptians and the Crusaders came to Lebanon, lived, raised families, and died there," Tyler-Smith said in a statement. "Their DNA sequences reveal this, but a little while later, there may be no trace of their genetics in the local population."