More about how evolution works; stasis (Evolution)

by dhw, Thursday, October 15, 2015, 12:16 (3325 days ago) @ David Turell

dhw: Why would an "optimal form" change? It may need to adapt (bacteria are a prime example), but that's all. The mystery is not stasis but innovation, and this might well happen if there are changes in the environment that allow for improvement. That doesn't mean innovations will always happen when the environment changes, and why should we expect it to? Each innovation has to take place within individual organisms, and that will require exceptional individuals. Once the “invention” works, it establishes itself, and if it's optimal, it won't change (= stasis).-DAVID: All we know is environmental changes cause modifications, which are reversible when the environment changes again. We do not know how complexity advances, as in the appearance of humans, and also illustrated by the non-change in bacterial complexity. [...] We've had glacial periods, hot periods, etc, and species survive unchanged. They must be perfectly adapted to total survival. This does not explain increasing complexity which must be a very specialized process, relegated to only certain groups of organisms. Smells of a designed evolutionary plan.-There is no disagreement here. You are repeating my own arguments in your own words: "environmental changes cause modifications" = adapt; “how complexity advances”, “increasing complexity” = my “innovations”; “very specialized process” and “certain groups of organisms” = my “exceptional individuals”. The only difference between us is your insistence on “a designed evolutionary plan”, whereas I would argue that the whole process smells of organisms doing their own thing.