(CN) - An analysis of ancient Roman DNA reveals links between the genetic origins of Rome’s denizens and Roman Empire’s tumultuous and violent expansion across ancient Europe, Asia and the Mediterranean, according to a study released Thursday.
Within 800 years after Rome’s founding as a city-state - traditionally dated at 750 BC - the Roman Empire had expanded west to Britain, south into North Africa and east into Syria and Iraq.
The vast empire encompassed the entirety of the Mediterranean region with all roads leading to Rome, its sprawling capital.
Known today as the Eternal City, Rome was the first in the ancient world to surpass one million residents, a feat that remained unrivaled in Europe until the dawn of the industrial revolution nearly 1,500 years later.
While archaeologists and historians have documented ancient Rome and central Italy's distant past, less is known about the genetic origin of people who called the cultural crossroads of the ancient world home.
Stanford University researcher Margaret Antonio and colleagues set out to fill the gap, analyzing 127 ancient DNA samples from 29 archaeological sites in and around Rome dating from between the Stone Age and medieval times.
The analysis revealed two major migrations that were critical in shaping genetic variation in Rome, as well as significant shifts in population within the last few thousand years, according to the study published in the journal Science.
First, Neolithic farmers, descended from early agriculturalists from Turkey and Iran, replaced Mesolithic hunter-gatherers in the region between 7,000 and 8,000 years ago, the study found.
Later, Bronze Age traders, artists and thinkers flooded Rome as it became one of the world’s first great cities.
As the Roman Empire expanded across the continents through war, trade and other ventures, immigrants and enslaved people from North Africa, the Mediterranean, Asia and Europe became part of the genetic makeup of the region.
A massive shift in Roman residents' ancestry originated in the Eastern Mediterranean and Near East, which researchers speculate was due to the Roman Empire's presence there as opposed to its reach in Europe and Africa.
In the centuries that followed, the Roman Empire split in two, the Eternal City was decimated by disease and a series of invasions, which propelled a shift toward western European ancestry.
Later, the rise of the Holy Roman Empire fomented the migration of central and northern European people into the region.
Stanford University’s Jonathan Pritchard said in a statement that Rome’s genetic makeup reflects political and social shifts across centuries.
“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 said. "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.”
Ancient skeleton’s DNA samples have been used in the last decade to fill gaps in the histories of other regions of the world, the study authors said.
"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," Pritchard said
According to Stanford’s Hannah Moots, researchers plan to expand the geographic range of ancient DNA samples and study the evolution of traits like height, lactose tolerance and resistance to diseases such as malaria.