1857-1927

Danish Geneticist and Botanist

Wilhelm Johannsen is considered one of the founders of genetics. His research provided evidence supporting the mutation theory of Hugo de Vries (1848-1935), which holds that there are sudden, spontaneous appearances of new characters or traits in existing species. Johannsen's research appeared to counter Charles Darwin's (1809-1882) theory that changes in species occur slowly through the process of natural selection alone. Johannsen came to believe that both natural selection and mutations in the hereditary units of germ cells act as influences on subsequent progeny, thereby changing species through the evolutionary process.

Born the son of a Danish army officer and German mother, Johannsen's schooling in Copenhagen was stopped short of the University level because his father did not have the financial means to provide for his tuition. Johannsen served as a pharmacy apprentice in Denmark and Germany, and passed...