1900

Events that occurred in the year 1900 CE.

Events

 * January 1: Hugo de Vries completes work which independently rediscovers Gregor Mendel's theories, having been working on similar experiments for several years prior. Erich von Tschermak, and Carl Correns also rediscovered and verified Mendel's work later in the year, marking the beginning of modern genetics.
 * June 14: Karl Landsteiner classifies blood into four types, allowing for the first safe blood transfusions.