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

by dhw, Thursday, July 22, 2010, 17:15 (5237 days ago) @ George Jelliss

George has taken me to task over my post on gradualism. -I wrote that I did not regard different eye colours and number of molars as having any bearing on the way complex organs arise out of mutations or adaptations. George cites the famous beaks of finches as a further example. None of these are NEW ORGANS. They are variations on existing organs. I wrote: "If an innovation is not successful, it will not survive," to which George responds: "Why not? If it is only a slight change, like a sharper tooth or a differently shaped beak it need make no difference, it will just add to the variation within the population." A variation is not an innovation.-I wrote: "It seems reasonable to me to argue that new organs will gradually be refined and improved by natural selection", but you have ignored this sentence, which I would have thought makes the distinction clear. A new organ is a heart, a liver, a kidney, an eye, a penis. And no matter how rudimentary the innovation itself may be, even through exaptation or gene duplication, (a) it is still complex, (b) it still has to work, and (c) you still have to account for the original organ. -"For this reason Darwinism has concentrated on the evolutionary development of existing organs." -The above quote is taken from -[link=http://]http://creation.com/images/pdfs/tj/j19_2/j19_2_76-82.pdf[/link].-I have never claimed to be "a great expert on these things", and rely on others in the field. I suspect you do too, so please read the article. Try to ignore the word "creation". This is a straightforward account by an expert on the problem I have tried so inadequately to explain.-Still on the subject of complexity you wrote that "a nerve is simply a piece of tissue that transmits a message in some form along its length." Why SIMPLY? It has taken thousands of years for intelligent humans to refine their methods of transmitting messages. If you think nerves are "simple", have a look at 
http://en.wikipedia.org/wiki/Nerve-Here is a sample: "Each nerve is a cordlike structure that contains many axons. These axons are often referred to as "fibres". Within a nerve, each axon is surrounded by a layer of connective tissue called the endoneurium. The axons are bundled together into groups called fascicles, and each fascicle is wrapped in a layer of connective tissue called the perineurium. Finally, the entire nerve is wrapped in a layer of connective tissue called the epineurium." Simple?-I find it unreasonable to assert that mutations and adaptations are initially not complex, and that such innovations (see above) can only come about gradually. You responded: "Well, this is absolutely denying Darwin's entire thesis!"-It is not Darwin's entire thesis, but Darwin said his thesis depended on it, and this whole thread is my attempt to find out why. An essential element of Darwin's thesis is the argument that all life has descended from a few forms or one, and that natural selection will result in the survival of advantageous changes. The example of finches' beaks brilliantly illustrates how a modification can over time result in a different variety, but a beak is still a beak and a finch is still a finch. You wrote: "dhw's insistence that evolution can only occur in big jumps entirely goes against Darwin's thesis." That is a slight misrepresentation of my argument. Innovations ... as opposed to variations ... entail a jump (maybe big, maybe small), and they may gradually be refined and improved. What I do not understand is why Darwin insisted that there were no "jumps in Nature", or that any jumps would invalidate the theory that we are all descended from one or a few forms via a process of natural selection.