Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site utastro.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!ihnp4!zehntel!hplabs!hao!seismo!ut-sally!utastro!bill From: bill@utastro.UUCP (William H. Jefferys) Newsgroups: net.origins Subject: Re: Perhaps probability Message-ID: <426@utastro.UUCP> Date: Thu, 23-Aug-84 13:44:23 EDT Article-I.D.: utastro.426 Posted: Thu Aug 23 13:44:23 1984 Date-Received: Sun, 26-Aug-84 01:39:22 EDT References: <539@denelcor.UUCP>, <220@uwmacc.UUCP> Organization: UTexas Astronomy Dept., Austin, Texas Lines: 88 > I quote Bill Jefferys: > > First, picking a given protein (e.g., insulin) and showing that > the probabilities of evolving one of a particular group of insulin > molecules is small (however large the group), fails because probability > theory tells us nothing about what *has* been observed, only about > what *may be observed in the future*. > > This sounds to me like "probability is inapplicable to the past". > Perhaps I'm reading too much into it. Mr. Jefferys may wish > to respond here. I will be happy to expand on my point, which is not entirely clear from the quotation. Let me give an example. I, Bill Jefferys, have a unique complement of genes, inherited from my parents. Through processes which are well understood, each pair of genes in my DNA consists of one randomly selected from that site in my father's DNA, and one similarly selected from my mother's. The probability that I inherited that particular pair of genes is easily calculated to be 1/4. But I have thousands of genes. This means that the a priori probability that my parents would have given birth to an individual with my precise complement of genes is only (0.25)**n, where n is several thousands, at least. This is a number which is at least as small as the one in 10**400 kind of number that is constantly being bandied about by creationists in their probabilistic arguments alleging to show that proteins couldn't have arisen by chance. There is no doubt about it: I am a unique individual, and my particular complement of genes will, almost certainly, never appear again in the future history of the universe. It is equally unlikely that it ever occurred in the past. One cannot conclude from this fact that my genes were not selected by random processes. Furthermore, as has been pointed out by others, the assumptions used by creationists to calculate the probabilities of obtaining biologically active proteins are invalid. There is considerable evidence that biologically active macromolecules form a rather substantial fraction of the set of all the possibilities. This includes the facts that (1) in typical proteins, only a handful of sites must be occupied by particular amino acids for the protein to have its normal function; (2) examples are known of nucleic acid sequences that code for entirely different proteins, simply by reading them shifted by one base unit (that would be like taking this article and parsing it shifted by one letter to obtain a meaningful article on another, completely different subject); (3) the sequence of bases that specify some of the most ubiquitous proteins actually consist of very short - and therefore highly probable - sequences that have been duplicated and reduplicated. > Failure on our part to demonstrate the validity of our argument > (although I haven't conceded that) doesn't validate the > proposition that complex organic compounds arose by non-directed > processes. The point of my article was to indicate that no > evidence has been put forth to demonstrate such a proposition, > and that the arguments for it proceed along the lines of > speculation (as they necessarily must). The ideas advanced > within those arguments may be based on known and accepted > scientific phenomena, but they prove nothing relative to the > validity of the proposition. Because organic processes > occur in certain ways, given that the organic compounds exist > today, proves zero about how they got that way in the first > place. If it's so easy to get these compounds together, > someone please submit references regarding their creation > (unfortunate word) in the laboratory from the raw materials. > And also regarding what keeps them from decomposing as fast > as they arise. On the contrary, there is a good deal of evidence in the geological record that there was a period when life did not exist, a later period when only very simple forms of life existed under reducing conditions, and a still later period where oxygen slowly accumulated in the atmosphere and life forms became more and more complex. Each of these periods lasted for hundreds of millions to billions of years. There is also a very large body of laboratory experiments, going far beyond what Miller and his associates did many years ago (which is all many creationists seem to be aware of), which have greatly advanced our understanding of how life was formed. I will recommend again that instead of ignoring the existence of the geological and laboratory evidence, creationists would do well to learn about what has been accomplished. "Genesis on Planet Earth", by William Day (Yale 1984) is an excellent, somewhat technical summary of current understanding. It also has an excellent bibliography including literally hundreds of papers in the scientific literature which are relevant to these questions. -- Bill Jefferys 8-% Astronomy Dept, University of Texas, Austin TX 78712 (USnail) {allegra,ihnp4}!{ut-sally,noao}!utastro!bill (uucp) utastro!bill@ut-ngp (ARPANET)