Background: Advances Between 1900-1949

Early in the twentieth century the rediscovery of Gregor Mendel's (1822-1884) work on heredity in pea plants led to the development of the field of genetics. In the 1940s Oswald Avery (1877- 1947) and his research associates at the Rockefeller Institute in New York found that DNA was the genetic material, the chemical information passed on from one generation to the next, that determines traits in all species. At about the same time, a group of researchers from a number of different areas of biology—zoology, ecology, genetics, and paleontology—developed what came to be called the Modern Synthesis, the updating of Charles Darwin's (1809-1882) theory of evolution to incorporate the new discoveries in genetics and other areas of biology. It was also during the first half of the century that ecologists developed mathematical methods for describing changes in...