Gradualism in Evolution (was Categories ...) (Agnosticism)

by David Turell , Thursday, July 22, 2010, 15:59 (5237 days ago) @ George Jelliss

Of course it has a bearing. It's by such minor changes that more major changes come about; for instance one can easily visualise teeth gradually developing into sharper points allowing for a change to a different diet, or what about the famous beaks of the finches.-Beak size changes back and forth adapting to the climate. the species otherwise show no changes.-> 
> Doesn't a slightly differently shaped beak more suited to opening certain nuts, say, constitute a successful mutation? This doesn't seem to involve any increase in complexity at all.-Again we are discussing minor adaptations-
> But why should any of the steps in this process be big jumps in complexity? A nerve is simply a piece of tissue that transmits a message in some form along its length. In a simple form it could just conduct heat, when its outer end touches a hot object. It would also be heated up when infrared rays impinged on it (heat being simply vibration of the molecules). A slightly greater sensitivity and it could detect red light rays.-Remember ion exchange runs down the nerve. Nerves do not conduct heat or pain, just electrical impulses. The brain has to develop the mechanism to sort out interpretations of the stimuli received in the cortex. In human babies two-point identification of pricks on the skin is learned(!)as they grow and can see where the pricks are.-> 
> dhw admits: "Well, OK, maybe a small mutation is only a small jump, but a big mutation will be a big jump."
> 
> Yes and big mutations are usually unsuccessful mutations.-Just as in the Cambrian Explosion I presume.-> On the contrary, as dhw's original quote from Darwin himself says, dhw's insistence that evolution can only occur in big jumps entirely goes against Darwin's thesis.-Exactly the point. Current reearch in epigenetic controls brings Lamark back into the picture. Evolution occurred, no question. At least Ernst Mayr was right on that point when he rejected the mathematicians, in the 1967 Wistar Institute conference, who said gradual mutations were to slow for the time allotted for that to be the mechanism. Gould and punctuated equilibrium must be respected, as another point. By this time the missing fossils should have popped up.