ABSTRACT
Examination of the data of the fossil record has led some workers to espouse a theory (‘punctuated equilibria’) in which evolutionary change is hypothesised to be concentrated in relatively short periods of geological time. These metastable periods are then supposed to be followed by long periods without change. Such theories are based on limited data, both with regard to the lengths of time embraced and the biology of the characters involved. Punctuated equilibria cannot be directly applied to evolutionary theories that are based on the biology and genetics of contemporary populations. The accomplishments of studies on the genetics of natural populations in this century are reviewed. Empirically and theoretically, the approach to evolution through population biology (Neo-Darwinism) is highly robust. All evolutionary processes including varying rates and periods of stasis can be understood by recourse to studies of contemporary organisms. There is no reason to believe that any basic principle can be observed in the fossil record that it not also reflected in population biology.
