ADELAIDE, AUSTRALIA—According to a statement released by Flinders University, archaeologists Maciej Henneberg and Teghan Lucas of Flinders University and Kara Holloway-Kew of Deakin University analyzed data collected on some 70,000 ancient skeletons spanning a period of about 200 generations in order to study the spread of infectious diseases. Certain pathogens, such as the ones that cause tuberculosis, treponematoses, and leprosy, take time to reproduce and spread, and can leave distinctive marks on bone before they kill their host, the researches explained. The study suggests that these pathogens caused more skeletal changes when they first spread through human populations, but then became less common over the past 5,000 years. Lucas said the germs may have adapted so that they caused less harm to infected people, which they depend upon for their own survival, in order to continue to spread to additional individuals. Eventually, people may have also adapted to the infections so that they experienced less illness, and may have become even tolerant or immune to them. To read about the pathogen that was responsible for the Plague of Justinian and the Black Death, go to "A Killer Bacterium Expands Its Legacy."