hua@cmu-cs-edu1.ARPA (Ernest Hua) (03/26/85)
______________________________________________________________________ > From: jeff@rtech.ARPA (Jeff Lichtman) > > I agree that the argument is flawed, but I think the second er- > ror, not the first, is the fatal one. The argument could just as > easily have been "how could an organism so complex as a human be- > ing have evolved through a random process?" You can dispute the > perfection of the human organism, but not its complexity. > > I feel that the fatal flaw in the argument is that it assumes > that evolution is completely random, i.e. according to the theory > the first human must have suddenly sprung into being after mil- > lions of years of random juxtaposition of genes (or proteins, or > body parts, or what have you). That is not how evolution works. > Each living organism has descendants. Most of the complexity of > human beings was already developed in our ape-like ancestors. > > Here is a thought experiment. Imagine that you have 50 dice, and > that your goal is to get them all to show 3 on their uppermost > faces by some random process. You could roll all 50 dice over > and over again until all threes show. If you threw the dice once > a second, the expected time until success would be (6**50)/2 > seconds (for you non-programmers, this means 6 to the 50th power > divided by 2). The reasoning is that, on the average, you should > expect to go through half of the possible arrangements of the > dice before you hit on the right one. > > Now suppose that take you one die and roll it until you get a > three. When that happens, take a second die and roll it until it > shows a three. Continue this until all of the dice show threes. > This will take much less time than the above method, about 3 > times 50 seconds if you roll once each second. Here the resoning > is that, for each die, you should expect to go through half of > the possibilities before getting the one you want and proceeding > to the next die. With this method, you would spend about 150 > seconds versus an extremely long time with the other method. > > Evolution works something like the second method. It doesn't > "try" all possible combinations until it hits the right one. > Rather, it "tries" incremental changes to already existing organ- > isms. > > I don't mean to imply that, because there is a goal of obtaining > all threes in the thought experiment, that I believe that human > beings were a goal of evolution. Evolution doesn't have goals, > unless one considers survival of the fittest to be a goal. Human > beings evolved into their present form only because of the cir- > cumstances of their ancestors. If, for instance, the climate > were much colder when humans evolved, then we might all have > thick fur. > > Please don't think that I reject the "punctuated equilibrium" > theory because of my above arguments. I believe that it is more > likely than gradualism, based on the evidence. My thought exper- > iment was only intended to show that order can come out of random > processes in a relatively short length of time if partial results > are preserved along the way. Thank you for the correction and the excellant example that followed. ______________________________________________________________________ Keebler { hua@cmu-cs-gandalf.arpa }