[r.p.bibra]

dear Greg, here is copy from an article on the subject of "natural selection" by an Indian nuclear scientist:

By Prof. G Venkataraman)

The essence of Darwin’s theory might be stated as follows: In the beginning, there was one living being – the ancestor of all of us. Darwin assumed this. being was far from complex. From this being emerged, in due course, other species, of greater and greater complexity, species that were better suited to survive.

Young Charles Darwin

Now how did this happen? Darwin suggested that it was due to random mutation of the genes. When genes of a species suffer mutation, it leads to the emergence of another species, with slightly different characteristics. So from one species, there come a family of species; these then compete for survival, and the fittest species emerges as the victor. And once again, mutation, more descendent species, competition for survival, and finally a victor. This goes on and on for millions and millions of years and at the end of it all we have fishes, amphibians, birds, mammals of various kinds, monkeys, and finally man.
We must remember that Darwin did all his hypothesising in the middle of the nineteenth century when Science was yet to cross many, many new frontiers. In effect, it was a broad-brush theory. Of course, Darwin himself made additions and subtractions later, but in spite of it all, at the time of the John Scope trial, Darwin’s Theory still had huge gaps. Yet it provided a plausible, scientific framework, and that was what excited biologists.
Science Seeks Answers to Our Origins
OK, let us move on and come to say the sixties of the twentieth century. By this time, many developments had taken place in the field of Science. The most important from the point of evolutionary biology was the discovery of the molecular structure of DNA by Crick and Watson in 1955, for which they duly received the Noble Prize. Thanks to this, one could now talk about mutation at a molecular level, which of course made a lot of sense.
The second important development concerned intensive studies on the origin of life itself. You will recall that Darwin assumed a primitive ancestor. Where did this ancestor come from and how? It was known by then that the age of the Universe was around fifteen billion years, the age of our earth is about five billion years, and life probably first appeared on earth about four billion years ago. The question was, how?

The fusion of molecules

This made scientists go back to the condition that existed on the face of the earth four billion years ago. They had a reasonably good idea of the nature of the atmosphere, which, incidentally, was very different from what it is today. Believe it or not, there was little or no oxygen then. But there were various other gases like methane and so forth. So people started doing experiments to see what would happen in such atmospheres if there were powerful lightning discharges. They found that a huge variety of complex molecules would be formed in the atmosphere, which would then come down with rain - methane rain perhaps - and get into the ocean. Thus, in due course, the ocean was expected to be teeming with all kinds of molecules colliding with each other constantly.
Now, when molecules collide, many things could happen. They could, for example, break up. But they could also combine to form a bigger and more complex molecule. It was then hypothesised that this process of constant collisions threw up one day, purely by chance, a big molecule that contained life.
This raises the question: What exactly is life? We still don’t have a precise scientific answer to this question but in those days, most people went along with Academician Oparin of Russia who said that a living entity must exhibit three characteristics: Firstly it must exhibit metabolism, meaning it must take in high-grade energy and, after using it, throw out the waste as low-grade energy. Next it must grow, then decay, and finally die. In addition, it must be able to reproduce. This was a reasonably good working definition and this is what most people accepted then.
Life: A Matter of Probability?
OK, has anybody been able to find anything definite about this primordial and prehistoric ancestor of ours? The answer is NO. The speculation still remains but meanwhile, many people have questioned the entire idea on purely probabilistic grounds. These people simply said, “Let us assume that indeed, due to random collisions, a living molecule was produced about four billion years ago. But let us do a little calculation involving collisions and check how long it would take for such a chance event to occur.” When that mathematics was done it was found that it would take a billion times the present age of the Universe.
Let us pause and absorb the whole argument. There are three points to consider here. The first is the outcome, the second is the process by which the outcome is realised, and the third is the probability. In this case, the outcome is the production of a living molecule in the ocean of those times, which is often called the primordial soup. As for the process, it is, as I have already mentioned, random collisions. Lastly, there is the probability business.



To appreciate this point better, let us consider the following example: I start tossing a coin. As you know, when I do that, I would get either heads or tails. Everyone knows that on the average, heads would occur fifty percent of the time and tails would occur fifty percent of the time. OK. Now it is quite likely that sometimes I may get two heads in succession. Let us suppose that I go on tossing in the hope that I get a thousand heads in succession. In principle, this is possible, but in practical terms, it is highly improbable. How does one quantify this highly improbable business? One says, using math, that the chance of this happening is one in trillion, trillion, trillion or something like that, and then one adds, “If I do one toss every second, this would mean so many billion, billion years of wait before I get thousand heads in a row.”
One has to carry over this kind of argument into the business of a living molecule being formed in the primordial soup as the result of random collisions. When that is done, one finds that the current age of the universe is too small for such a molecule to have emerged. Remember, in Darwin’s theory, not only the primordial living molecule, but everything including plants, trees, crocodiles, tigers, monkeys and humans, must come through as the result of random processes within fourteen to fifteen billion years, the approximate age of the Universe. So you see, probability puts a huge roadblock up right at the beginning. Keeping in mind the enormous complexity of living systems, Fred Hoyle, a great astronomer, put it like this: “The current scenario of the origin of life is about as likely as the assembly of a fully operational Boeing 747 by a tornado whirling about in a junk yard.”
A New Piece of the Puzzle: DNA and Genes

DNA - mystery molecules

That raises the question: “Where then did Darwin’s ancestor come from?” Hoyle has madesome interesting suggestions concerning that but I shall not get into that topic here. Let me move on to other aspects. Let me get back to the DNA, to which I made a brief reference earlier. This molecule, whose full name - de-oxyribo nucleic acid - has a remarkable structure: that of two spirals twisted around each, with innumerable steps linking them. DNA is sometimes called the molecule of life, and with good reason.
DNA gave genetics its backbone and brought it down from the macro to the micro-level. Naturally, the discovery of the structure of the DNA spurred evolutionists to look at Darwin’s Theory from a molecular point of view. No doubt, this has lead to huge leaps in understanding, but many questions and big gaps still remain. I am not an expert in this topic and I obviously cannot go into the details. But I can certainly point out some of the issues.
By and large, most people seem to be convinced that Darwin’s Theory with all its modern nuances, does offer a concrete framework for understanding evolution. But, difficulties that cannot be swept under the rug include the question of the primordial ancestor, to which I have already made a reference. There was the additional question of random mutations followed by natural selection. I went over this rather quickly earlier; maybe I should say a few more words at this juncture, because it is an important issue.
In Darwin’s Theory, species ‘B’ say, emerges from parent species ‘A’, through random mutation of the genes of A. Along with B, there may also be species ‘C’, ‘D’, and so on. All these newly emergent species, B, C, D etc., would be similar to their ancestor species A, but also different in many respects. Now all these species would compete for survival, and eventually, among the daughter species, that which is best suited to survive would actually survive. This is the basic idea behind the survival of the fittest hypothesis.
It all looks fine, especially on a macro scale, except for one problem thrown up by statisticians. I have already made a reference to this earlier when I quoted Fred Hoyle. In the context, there is one more famous quote that is sometimes used, a quote that goes back to Sir James Jeans, a famous astronomer who lived in the early part of the twentieth century. Jeans said that if we had a group of monkeys all trained to press the keys of a typewriter, and if these monkeys were allowed to keep on typing endlessly, then, even though they would be pressing the keys in a purely random fashion, it is possible for one of the monkeys, perhaps after millions of years, to type out completely a sonnet of Shakespeare, by sheer chance of course. By the way, if you browse the net, you will find a lot of interesting material about this monkey business. What I am driving at is that though in principle, a monkey might one fine day actually crank out an entire sonnet of Shakespeare, it is in practice highly improbable, unless one waits a trillion, trillion years or something like that. In the same way, for a series of lucky random mutations to occur to bring us to where we are would require an impossibly long time. So people started asking the question: “It looks like evolution did occur due to gene mutation, but is it possible that the mutation was not entirely random?”
love&regards.ls