To anyone unfamiliar with the equations of population genetics by which neo-Darwinian evolutionary biologists estimate how much morphological change is likely to occur in a given period of time, 40 to 50 million years may seem like an eternity. But empirically derived estimates of the rate at which mutations accumulate imply that 40 to 50 million years does not constitute anything like enough time to build the necessary anatomical novelties that arise in the Cambrian and Ediacaran periods.
