In June 1909, scientists and dignitaries from 167 different countries gathered in Cambridge to celebrate the hundredth anniversary of Charles Darwin’s birth and the fiftieth anniversary of the publication of Origin of Species. The event was one of the most magnificent commemorations in the annals of science. Delegates gathered within the cloisters of Cambridge University not only to honor the “hero” of evolution but also to reassess the underpinnings of Darwinism at a critical juncture. With the mechanism of natural selection (...) increasingly under attack, evolutionary theory was in disarray. Against this backdrop, biologists weighed the impact of several new developments—the rediscovery of Mendel’s laws of heredity, de Vriesian mutation theory, and the linkage of sex‐cell division to the mechanism of heredity. The 1909 Darwin celebration thus represents a significant watershed in the history of modern biology that allows historians to assess the status of evolution prior to the advent of the chromosome theory of genetics. (shrink)