Published online by Cambridge University Press: 05 May 2010
Rolf Gruner (1977) has argued that natural selection plus time does not entail, and hence does not explain, evolution. This according to Gruner is the result of the undeniable fact that evolution involves an increase in the complexity of organisms:
Since increase in complexity is part of the concept of evolution, evolution is not explained by the theory of natural selection. The Darwinian or Neo-Darwinian affirms the reality of evolution and seems to believe that it can be accounted for in terms of natural selection. But it could be accounted for in this way only if the assumption were justified that generally the more complex organism is better adapted to its environment, and thus stands a better chance to survive and breed, than the less complex organism. And this assumption is not justified. “The more complex, the better adapted” will not do even as a rule of thumb, as most biologists today will be prepared to admit (711).