Whoa! Whoa! dhw take notice!!! (The limitations of science)

by dhw, Sunday, April 20, 2014, 11:59 (3630 days ago) @ xeno6696

Matt has returned to his argument that Natural Selection is "the most important part of the process" of evolution. Our disagreement (which he also has with David) is vividly illustrated by the following exchange:-DAVID: Natural selection never creates variety.-MATT: Yes it does: It is responsible for forcing organisms to adapt. [...] Simple case: Asteroid crashes into the earth. THAT is the impetus that then FORCES organisms into rapid adaptation.-I simply cannot see how an asteroid crashing into the earth can be called Natural Selection. It is ... or results in - a change in the environment. But if the change kills every single organism, there will be no evolution. Only those organisms that can adapt to the new environment will survive, and those are the ones that Nature "selects". Yes, the asteroid (changed environment) is the trigger, but the selection can only take place when organisms do or do not adapt, and adaptation could not happen unless some organisms were already possessed of the mechanisms that allowed them to change. David has quite rightly asked what you think the term "Natural Selection" means, and I'm almost sure I've asked you that every time we've had this discussion. I have never seen a definition along the lines of: "NS is the change in the environment which causes organisms to adapt and either survive or perish." It's always the other way round: "NS is the process by which those organisms best able to adapt to a particular environment will survive." In other words, the order of events with your asteroid is: 1) environment change, 2) adapt or die = selection.-Evolution is not just adaptation anyway. Adaptation generally preserves, but evolution requires innovation, and although Romansh is right that there are lots of ideas, David is right that nobody knows how it happens. From your perspective, though, you can argue that changed environments may be the trigger. And I will argue that a change in the environment is the first stage in the process of change, and NS is the last. ALL the stages and mechanisms are indispensable, and so what is the point in claiming that one or other is "the most important part"?-Finally, once more, please give us your definition of Natural Selection.


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