Celebrating Darwin's Errors How Should We Mark the Darwin Bicentennial?
Allchin, Douglas, The American Biology Teacher
Charles Darwin was truly amazing. In 1859 he introduced a robust understanding of descent with modification by means of natural selection. His concepts would help unify taxonomy, biogeography, comparative anatomy, heredity, morphological analysis, embryology, paleontology, population dynamics and ecology, and even human moral behavior. Darwin showed how to explain organic "design" as well as the limitations of contingent history, adaptive structures as well as vestigial ones. Every lesson in biology, properly framed, expresses and celebrates Darwin's achievement.
How, then, might one mark so august an occasion as his 200th birthday, February 12th this year (also the sesquicentennial year of his premier work, On the Origin of Species)? Many will no doubt want to parade Darwin's many triumphs. But allow me to take exception to the common view (another sacred bovine?) that science is best reflected only by its successful theories. If science is fundamentally about discovery, then its "failures" or errors along the way may be just as important as the ultimately reliable insights (Allchin, 2004; Allchin, 2008). I wish to celebrate science as a process. Here, then, I acknowledge Darwin's mistakes and show how understanding them gives us a deeper understanding both of Darwin and of science more generally. My tribute is to forego the mythologized legend and appreciate so remarkable a scientist as Darwin in familiarly human terms.
Was Darwin Ever Wrong?
First, one may note that Darwin's errors generate interest largely because of his many achievements. His credentials are unimpeachable. If he made mistakes, it was not for want of scientific ability. One cannot rudely dismiss his errors as due to ineptitude.
Indeed, Darwin's contributions are wider and their theoretical coherence deeper than popularly known (Ghiselin, 1969). He produced four volumes on the taxonomy of barnacles, demonstrating his skills in detailed observation and phylogenetic analysis. In his first work after the Origin, he showed the importance of orchid morphology in promoting outcrossing through pollination, thereby contributing further to an understanding of the role of sex and genetic recombination in evolution. Later, he explained heterostyly--the occurrence of flowers with different length styles--as illustrating the same general principle. Add, too, his work on the anatomy and physiology by which emotions are expressed, grounding a study of mental phenomena and social communication in concrete observables. In his last work, Darwin correctly interpreted the role of worms in forming topsoil (what he called "vegetable mould").
Darwin was also a skilled experimentalist (Dennison, 2006). Chapter 11 in the Origin summarizes some of his experiments on the effects of sea water on seed germination--a "test" of his ideas about how plants traversed the ocean. Biology teachers, in particular, may know that Charles and his son Francis investigated "the power of movement in plants"--documenting, measuring, and isolating the locus of phototropisms. These studies followed earlier experiments on the positive effects of plant hybridization. Darwin would surely be remembered for these works even if he had never written the Origin or Descent of Man.
In short, there is no deficit of Darwin's achievements.
Yet Darwin's conclusions were not always correct. Perhaps the most notorious of his ill-fated claims was his "retreat" to Lamarckian-like processes (Eiseley, 1961, pp. 216-221; Ghiselin, 1969, pp. 162164). While variation was essential to the process of natural selection, Darwin could not explain its sources. Sharp criticism worsened the problem. Darwin, rather than leave his theory incomplete perhaps, ultimately appealed to external forces (use or disuse, or habit, say) in generating favorable variants. That seemed to echo Lamarck's earlier idea (now discredited) of the inheritance of acquired characters. …