Epigenetics, revisited; new exciting studies (Introduction)

by dhw, Wednesday, September 28, 2011, 17:33 (4805 days ago) @ David Turell

Dhw: Darwin wrote: "If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down."-DAVID: This is not really an argument for gradualism. The argument here is irreducable complexity, a totally different philosophic beast. If you never have read Darwin's Black Box, it is a must to understand the true controversy. Can evolution make a liver? The liver digests, detoxifies (alters chemicals like antibiotics) perhaps more than the kidneys do, makes products like cholesterol, among other activities, and this all coordinates with other organs doing their things. Gradualism relates solely to species change, and that gradualism is out the window!!-Darwin is talking here specifically of complex organs ("Organs of extreme perfection and complication" in Difficulties on Theory), and in particular he deals with the eye. The articles you've drawn our attention to cover similarly complex mechanisms, e.g. what you call "the jump from marsupial pouches to placentas". Darwin even uses similar vocabulary to yours: "[Nature] can never take a leap, but must advance by short and slow steps." You're right, of course, that the ultimate controversy is chance v. design, but a crucial element of this discussion is whether complexity has arisen through tiny, gradual increments (Darwin) or major transformations over a short period. The atheist case is greatly strengthened by gradualism: the smaller the change, the less unlikely it will seem (Dawkins calls it "a continuous and shallow slope up Mount Improbable" ... The God Delusion, p. 124), but I'm suggesting that modern research is undermining that case: the shorter and steeper the route to complexity, the less likely it will seem that chance can produce it. -Since you yourself believe that evolution happened, the answer to your question "can evolution make a liver?" has to be yes! Your argument, however, if I've understood it correctly, is that something so complex cannot have assembled itself by chance, i.e. evolution is either programmed or (my designer alternative) guided by intervention.-Dhw: The main controversy is not about whether evolution happened, but about how, why, and over what period the changes took place.-DAVID: No! The true controversy is can chance make the complexities of living organisms? It comes down to who (?) or (what chance process(?) made the liver and had it work with the other organs?-Agreed, but the two controversies are interlinked. Going back to the quote at the head of this post, the demise of gradualism in the development of organs (and of species) would reduce the likelihood of chance processes, but that doesn't mean that all forms of life did not descend from preceding forms, that changes and innovations did not take place in existing organs and organisms, or that the filter of natural selection did not decide which changes did or didn't survive! I'm arguing simultaneously against chance but for evolution, and since Darwin was NOT trying to put the case for atheism, I still don't understand why he made his theory "absolutely" dependent on gradualism. You say you "fully understand it", so I'd be truly grateful if you would explain it to me!