Pandemic smallpox was responsible for 300–500 million deaths. As recently as the early 1950s, an estimated 50 million cases of smallpox occurred in the world each year. After successful vaccination campaigns throughout the 19th and 20th centuries, the WHO certified the eradication of smallpox in December 1979. To this day, smallpox is the only human infectious disease to have been completely eradicated, and one of two infectious viruses ever to be eradicated. Historically, measles was prevalent throughout the world, as it is highly contagious. According to the U.S. National Immunization Program, 90% of people were infected with measles by age 15.
Human extinction universe can support at least 10 biological human life-years; and, if some humans were uploaded onto computers, could even support the equivalent of 10 cybernetic human life-years. Without regulation, scientific advancement has a potential to risk human extinction as a result of the effects or use of totally new technologies. Some scenarios include: Normal biological evolution of humanity will continue and change humans over geological time scales. Although this could, in a non-phylogenetic taxonomy, be considered to give rise of a new species, such an ongoing evolution would biologically not be considered a species extinction. Given the likelihood that significant