“The bad habit of wandering”: Morgan, Osborn and the issue of evolutionary causality in genetics and paleontology

Abstract

According to George Gaylord Simpson, during the first decades of the twentieth century, the debate on evolution was featured by a deep contrast between genetics and paleontology. Simpson stressed that, while geneticists said that paleontology “had no further contributions to make to biology”, paleontologists felt that geneticists were studying organisms under “unnatural conditions”. These statements recall one of the most interesting debates in the history of American biology, that between Thomas Hunt Morgan and Henry Fairfield Osborn. This paper aims at analyzing such contention by highlighting how it was due not merely to an irreducible gap between genetics and paleontology, but rather to Osborn’s controversial attempt to integrate orthogenesis and Mendelism. I argue that Osborn’s synthesis between genetics and paleontology questions the much-discussed transition from ‘old’ to ‘new biology’ as well as the narrative of a clear break between orthogenetic and synthetic paleontology.