History of smallpox centuries, the WHO certified the global eradication of smallpox in December 1979. Smallpox is one of two infectious diseases to have been eradicated, the other being rinderpest, which was declared eradicated in 2011. It has been suggested that smallpox was a major component of the Plague of Athens that occurred in 430 BCE, during the Peloponnesian Wars, and was described by Thucydides. Galen's description of the Antonine Plague, which swept through the Roman Empire in 165–180, indicates that it was probably caused by smallpox. Returning soldiers brought the disease home with them to Syria and Italy, where it raged for
Human extinction biotechnology or self-replicating nanobots. The probability of anthropogenic human extinction within the next hundred years is the topic of an active debate. Human extinction needs to be differentiated from the extinction of all life on Earth (see also future of Earth) and from the extinction of major components of human culture (e.g., through a global catastrophe leaving only small, scattered human populations, which might evolve in isolation). "Existential risks" are risks that threaten the entire future of humanity, whether by causing human extinction or by otherwise permanently crippling human progress. Many scholars make an argument based on the size of