Zoonoses are pathogens that have natural reservoirs in nonhuman species and periodically or occasionally infect human individuals. Some of these can develop into persistent human outbreaks. Understanding the origin of human pathogens involves identifying ancient zoonotic transmission.
In the first part of a review of pathogens in human origins, I examine a sampling of infectious diseases in people today and their diverse origins.
New research suggests that herpes simplex virus 2 may have invaded ancient humans from chimpanzees sometime after 1.6 million years ago.