STS Lecture Series

Fossils, Genes, and the Origin of Species

Jeffrey H. Schwartz
Departments of Anthropology and
History and Philosophy of Science
University of Pittsburgh

Abstract

One of the exciting aspects of the relatively new discipline of "evo-devo" (evolution and development) is the appreciation that evolutionary novelty, and thus new species, might develop quite abruptly. This contrasts with the gradualistic models of evolutionary change proposed by the population geneticists T. H. Morgan and R. A. Fisher that came to inform the evolutionary synthesis of the 1930-40s. A historical review of the rise of genetics and other fields that came to inform evolutionary biology reveals that certain important facts that were known to the early geneticists have been "disappeared" from evolutionary discussion. The revival of these facts, plus the recognition that the same mode of inheritance that underlies the transmission of, say, eye color can also account for the sudden loss or gain of an eye, leads to a new and hierarchical way to think about evolution that distinguishes at one level notions of adaptation and, at another, the emergence of novelty and the origin of species. This model also makes sense of the fossil record of multicellular organisms, which portrays the abrupt appearance and disappearance of morphological structure. This lecture can be appreciated without a deep understanding of genetics or development.