Comparison of ancient pathogen genomes to their modern descendants reveals how the organism has changed over time, providing insight into their evolutionary past and clues about how they will continue to evolve today. In the same way that human evolution is impacted by pathogens (and the diseases they cause), pathogen evolution is impacted by humans. When humans and human ancestors migrated around the globe, they brought their pathogens along, creating new distributions of diseases. Human cultural practices, such as sharing of eating or drinking vessels, frequency of group gatherings, and even methods of medical treatment shape the pathogen’s evolutionary environment and the selective pressures it must face.
Ancient genomic studies of Y. pestis reveal how this disease shaped the genome of Europeans during the Black Death. Researchers found that humans have likely hosted the plague pathogen since at least the Late Neolithic period and that they carried it across the European continent via human networks. In many ways, the story of human evolution is intimately connected to the evolution of pathogens. They act as our constant and unsolicited companions. Many are never noticed, and yet they have (and continue to) shape our species.
Written by Stevie Winingear