Rome's history is extraordinarily well-documented through archaeological and historical records but now an international team of researchers has produced the first genetic history of Rome and central Italy, covering the last 12,000 years. The study, published in Science, shows two major shifts in ancestry over the millennia and many changes due to trade, migrations, and invasions.

“The historical and archaeological records tell us a great deal about political history and contacts of different kinds with different places – trade and slavery, for example – but those records provide limited information about the genetic makeup of the population,” senior author Jonathan Pritchard said in a statement.

The team extracted genomes from 127 individuals found across 29 archaeological sites in and around Rome going as far back at 10,000 BCE. The first major shift in genetic diversity happened during the Neolithic, roughly 8,000 years ago, when the local hunter-gatherer population gave way to farmers coming from Turkey and Iran, in line with similar genetic shifts in Europe. The second shift happened between 5,000 and 3,000 years ago, when people with Ukrainian ancestry migrated into the region.

Rome's traditional foundation date is April 21, 753 BCE and the researchers were surprised to discover that by that point, the budding city and the surrounding areas were already inhabited by people who resembled modern European and Mediterranean people. It is particularly interesting to see how immigrants flocked from places such as the Near-East and North Africa to Rome, as it expanded around the Mediterranean sea, the shift in genetic history matching with what was happening historically with the capital city.

“This study shows how dynamic the past really is,” co-lead author Hannah Moots, a graduate student in anthropology at Stanford University, said. “In Rome, we’re seeing people come from all over, in ways that correspond with historical political events.”

Understanding the genetic analysis of a population helps with understanding the history of that people. It gives an idea of the full reach of the Roman Empire that might not be found in historical references by providing genetic evidence of the people that reached the center of the Mediterranean, whether because of slavery, conquest, or looking to trade.

Rome’s ascent and decline lasted for about 12 centuries, marked by different forms of government. First a monarchy, then a republic (though not in the modern sense of the word), and from 27 BCE to 476 CE, an Empire. The late republican and early imperial periods are both marked by incredible territorial expansion and this is reflected in the DNA analyzed by the researchers. During this time, the people of Rome had more in common with those of Greece, Syria, and Lebanon than western Europe.

“It was surprising to us how rapidly the population ancestry shifted, over timescales of just a few centuries, reflecting Rome’s shifting political alliances over time,” Pritchard explained. “Another striking aspect was how cosmopolitan the population of Rome was, starting more than 2,000 years ago and continuing through the rise and dissolution of the empire. Even in antiquity, Rome was a melting pot of different cultures.”

The team wants to continue applying this kind of study to a wider geographical area to better understand how people moved around in ancient times. They are also interested in the changing traits of people such as height, resistance to certain diseases, and even being lactose intolerant during this time.