Roman DNA project

[Epictetus]

By also utilisng strontium and oxygen isotope analysis it became apparent that about one-third of the individuals studied had immigrated to Rome after childhood, but the analysis could not reveal where they had originated from.

This is interesting. If I remember Brunt's Italian Manpower correctly, he suggested that in the city of Rome itself the organic population growth rate was basically zero, and all of its growth came from immigration.