2,000-year-old remains tell lost story of Imperial Rome’s immigrant class

When it comes to ancient Rome, most of what we know tends to be concerned with a very select group of people: wealthy, literate freemen. Which means that, for a city that comprised perhaps a million people at its height, we know shockingly little about the lives of the majority of its residents: immigrants and slaves.

Now, though, researchers have used certain kinds of bone analysis to examine human remains from Imperial Rome—and have gained new insights into the lives of thousands of humans ignored by the textual record.

In particular, the researchers, Kristina Killgrove from University of West Florida and Janet Montgomery from Durham University, wanted to hone in on a little-understood, but highly prevalent aspect of daily Roman life: immigration, both by choice and forced. Immigrants comprised a significant portion of the population, as slaves were around 40 percent of the population and free immigrants were perhaps 5 percent—but their stories are by and large untold (unless you consider ancient graffiti).

Yet these people obviously had an enormous effect on Rome, even though we can’t comprehend the full magnitude without better archaeological evidence. Thankfully, there is one way to gather some new knowledge about these people: bioarchaeology. As in, there is evidence locked in the bones of those who lived and died in Imperial Rome—and these researchers finally decided to unlock it.

Getting down to the bone

The team examined 105 skeletons buried in Roman cemeteries that date to the first through third centuries CE. Using the ratios of certain chemical isotopes, like oxygen and strontium, they were able to better understand where people lived before coming to Rome.

When rocks weather, they release strontium, which enters drinking water and is taken up by plants. From there, humans consume these substances and incorporate strontium into their bones. Since rocks aren’t homogenous in their composition across the world, the amount of strontium deposited your bones reflects the geology of your area—and therefore, bone analysis can reveal what region of the world a person comes from.

Oxygen also gets incorporated into the bones from drinking water, though what is reveals is a bit more specific.

“Oxygen isotopes, on the other hand, are related to environmental and meteoric water, and the values change based on factors such as latitude, rainfall, elevation, humidity, temperature, and distance from the coast,” wrote the authors in their paper, which is published today in PLOS ONE.

In short, the ratio of oxygen isotopes in bones shows whether the individual drank local water (in this case Roman) or nonlocal water while their bones were forming.

Using these isotope analyses, the team determined that eight of the 105 skeletons were likely migrants, mostly men and children, possibly from North Africa and the Alps. While it was impossible to tell when exactly they made their journeys, some of the children seem to have arrived between ages four and ten, as their adult teeth (which formed at different ages) reflected differences in isotope levels. It’s not possible at this point to determine their social status, but since they were buried in a necropolis, they were likely poor immigrants, or maybe even slaves*—as the wealthy were normally buried in mausoleums.

(*The fact that they may have come from North Africa has no bearing on their status as free or enslaved. Slaves in Rome were not a particular race and did not come from any specific area; many were simply war booty after Romans conquered a new region.)

Meanwhile, using carbon isotopes, they were also able to examine their diets. Different foods have different kinds and levels of carbon isotopes, which incorporates in the bone as well. After analyzing this, the researchers discovered that coming to Rome seems to have greatly shifted the migrants’ diets—a possible sign of acculturation. Their bones indicated they switched from eating wheat, legumes, meat, and fish to eating millet (and animals fed millet).

Voicing the voiceless

All in all, we are beginning to learn more and more about the lives of the majority of Romans, granting a new voice to those who were previously voiceless.

“Modeling migration to Imperial Rome is necessary for a deeper understanding of demographics, family structure, and gender roles, wrote the authors.

“This study has generated the first concrete data of individuals who were not born at Rome, but much more research is needed into a variety of data sets to fully contextualize questions about mobility in Imperial Rome and to move forward in employing bioarchaeology in Roman migration studies.”


Feature Image: Skull of skeleton T15, a 35- to 50-year-old male who was buried in a cemetery in the modern neighborhood of Casal Bertone, Rome, Italy. Isotope ratios suggest he may have been born near the Alps. (Credit: Kristina Killgrove)