Three years into a global pandemic, the fact that infectious disease is capable of reshaping humanity is obvious. But seen in the context of sixty thousand years of human and scientific history, COVID-19 is simply the latest in a series of world-changing pathogens. In fact, the role that humans play in social and political change is often overstated. Instead, bacteria and viruses have been the invisible protagonists of mankind's ever-evolving story. Today’s guest is Jonathan Kennedy, author of “Pathogensis: A History of the World in Eight Plagues.” We discuss how Neanderthals and other early species of humans died out—not because they were cognitively inferior to Homo sapiens but because they were vulnerable to the diseases they carried; how disease triggered the agricultural revolution and allowed it to spread; how plague outbreaks in the 6th and 7th centuries led to the creation of modern states in Western Europe and the transformation of Islam into a world religion; and how infectious diseases aided the colonization of the Americas but inhibited the colonization of Africa