Actually it looks like smallpox only existed since about the time statistics was invented: "our data clearly show that the VARV lineages eradicated during the

Actually it looks like smallpox only existed since about the time statistics was invented: "our data clearly show that the VARV lineages eradicated during the 20th century had only been in existence for ∼200 years" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5196022/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5196022/ "The German Statistik, first introduced by Gottfried Achenwall (1749), originally designated the analysis of data about the state, signifying the "science of state" (then called political arithmetic in English). It acquired the meaning of the collection and classification of data generally in the early 19th century." https://en.wikipedia.org/wiki/History_of_statistics https://en.wikipedia.org/wiki/History_of_statistics This correlation suggests that as soon as people stopped using their gut feelings smallpox evolved to take advantage.