Lamarckism - History - 1880 To 1930

1880 To 1930

The period of the history of evolutionary thought between Darwin's death in the 1880s and the foundation of population genetics in the 1920s, and the beginnings of the modern evolutionary synthesis in the 1930s is sometimes called the eclipse of Darwinism by some historians of science, because during that time many scientists and philosophers accepted the reality of evolution but doubted whether natural selection was the main evolutionary mechanism. Theories involving the inheritance of acquired characteristics were among the most popular alternatives to natural selection, and scientists who felt that such Lamarckian mechanisms were the key to evolution were called neo-Lamarckians. Proponents included the British botanist George Henslow who studied the effects of environmental stress on the growth of plants in the belief that such environmentally induced variation might explain much of plant evolution, and the American entomologist Alpheus Packard who studied blind animals living in caves and wrote a book in 1901 about Lamarck and his work. Also included were a number of paleontologists like Edward Drinker Cope and Alpheus Hyatt who felt that the fossil record showed orderly, almost linear, patterns of development that they felt were better explained by Lamarckian mechanisms than by natural selection. Some people including Cope and Darwin critic Samuel Butler felt that inheritance of acquired characteristics would let organisms shape their own evolution, since organisms that acquired new habits would change the use patterns of their organs, which would kick-start Lamarckian evolution. They considered this philosophically superior to Darwin's mechanism of random variation acted on by selective pressures. Lamarckism also appealed to those, like the philosopher Herbert Spencer and the German anatomist Ernst Haeckel, who saw evolution as an inherently progressive process. The German zoologist Theodor Eimer combined Larmarckism with ideas about orthogenesis. With the development of the modern synthesis of the theory of evolution and a lack of evidence for either a mechanism or even the heritability of acquired characteristics, Lamarckism largely fell from favor.

In the 1920s, experiments by Paul Kammerer on amphibians, particularly the midwife toad, appeared to find evidence supporting Lamarckism, but his specimens with supposedly acquired black foot-pads were found to have been tampered with. In The Case of the Midwife Toad Arthur Koestler surmised that the tampering had been done by a Nazi sympathiser to discredit Kammerer for his political views, and that his research might actually have been valid. However most biologists believe that Kammerer was a fraud and even among those who believe he was not dishonest most believe that he misinterpreted the results of his experiments.