Wednesday, March 04, 2009

Darwin's anniversary

This year marks the 200th anniversary of Darwin's birth and the 150th anniversary of the publication of Origin of Species.

Richard Dawkins claimed in 1989 that "it is absolutely safe to say that if you meet somebody who claims not to believe in evolution, that person is ignorant, stupid, or insane (or wicked, but I'd rather not consider that)."

I suppose it all depends on what you mean by evolution. If you mean that various species undergo selection of genetic characteristics by their environment which make them more or less likely to reproduce these characteristics in their progeny - in other words the survival of the fittest, then of course this is true. In fact, it is a tautology. In a struggle for existence, those that are fittest to survive will survive.

If, on the other hand, by evolution you mean that life has begun as a matter of chance because of the happenstance of various chemicals mixing leading to the formation of amino acids, then protein, then nucleic acids, then some form of cellular organization, then more complex cellular forms until finally the prolific array of different species that now inhabits the earth, including all those that have become extinct, then anyone who believes that has never examined the evidence critically.

Evolutionary theories probably began with Thales of Miletus who lived between 640 and 546 BC. Darwin's contribution to the debate derived from his observations of the genetic variation of domestic animals and then his observation of natural variation on his time on the Beagle, especially at the Galapagos Islands. The mechanism that he related demonstrated that small variations are potentially present in every species and that environmental niches are indeed available that suit one variation over another. Given physical separation - either natural or produced by man - then it is possible to produce extreme variations within a species - a Toy Poodle or a Great Dane, for example, though there are limits to that variation and no-one has yet produced a tiger from a tortoise or a rabbit from a greyhound.

Darwin was a man of his time and he had no clear understanding of the mechanism eg this variation. This had to wait for Mendel's genetic experiments with peas, and even that idea had no physical equivalent until Crick and Watson fathomed out the DNA code.

Modern neo-Darwinism postulates a molecular model of random mutations that are selected for by the same 'survival of the fittest' tautology that Darwin hit upon. However, as we know, although mutations occur and are particularly useful for developing the immune response in the lymph node, elsewhere they are usually deleterious and are the chief mechanism of cancer. To suggest that they are the driving force of evolution envisions a highly improbable landscape.

Francis Crick himself (although no creationist) puts the problem clearly in his 1981 book Life Itself, Its Origin and Nature:

To produce this miracle of molecular construction all the cell need to is to string together the amino acids (which make up the polypeptide chain) in the correct order... Here we need only ask, how many possible proteins are there? If a particular amino acid sequence was selected by chance, how rare an event would that be? This is an easy exercise in combinatorials. Suppose the chain is about 200 amino acids long; this is if anything rather less than the average length of proteins of all types. Since we have just 20 possibilities at each place, the number of possibilities is 20 multiplied by itself some two hundred times. This is conveniently written as 20 to the power of 200, that is a one followed by 260 zeros!

The number is quite beyond our everyday comprehension. For comparison, consider the number of fundamental particles (atoms, speaking loosely) in the entire visible universe, not just in our own galaxy with its 100,000,000,000 stars, but in all the billions of galaxies out to the limits of observable space. This number, which estimated to be 10 to the power of 80 is quite paltry by comparison to 10 to the power of 260. Moreover, we have only considered a polypeptide chain of rather modest length. Had we considered longer ones as well, the figure would have been even more immense.

Even a simple bacterial cell comprises not just one protein, but a whole host of proteins that interact together in complex union.

Put simply, there are not enough molecules in the whole universe for even a simple protein to have evolved by chance.

Brick one in the wall of doubt.


Anonymous said...

Recently, there has been some suggestion that protein self-assembly wouldn't necessarily depend upon DNA or RNA. Replication could occur without those molecules, these scientists propose.

Going beyond even that, given a denial of God, where did the universe and the molecules that make it up come from, just so happening to be in a form that permits life? The atheist would say, chance, but I'd say that's even less likely than the random self-assembly of proteins in your example.

Burke said...

Where does it say that evolution is based on just chance?

Terry Hamblin said...

Thank you for your contribution, Burke, but all that that article says is that random chance produces mutations which are conserved by natural selection. It envisions natural selection acting as a ratchet or valve, that prevents the two-way flow which mutations would otherwise produce. It further suggests that the suitability of a particular mutation for retention is governed by natural law - the physical nature of the universe - gravity and other elemental forces.

I am afraid that that just pushed the question of origins back a few paces. Where does the natural law come from? The alternative explanation, that this perception admits is that a 'God' is a guiding force for the selection (so called 'theistic evolution').

There are a lot of adherents to that theory. I am not one of them.

Burke said...

Dr. Hamblin writes,

"Where does the natural law come from?"

Why do you assume that it must "come from" anywhere?

How can there be any such place, a place that's not really a place?

And how does positing that there is a God behind it all solve anything? You are just left with the question of where God came from, where whatever created Him came from...and so on and on in an infinite regression.

Cause and effect applies only to things that already exist. It cannot apply to the fact of existence itself as there can be no such thing as a non-existent cause.

No matter what you think about evolution, you are still left with coming up with a better explanation for what has happened in the past than that it was created in seven days, etc.

Terry Hamblin said...

I intend to consider the question of order from disorder in a future post, but the explanation of origins given inthe link that you cited demands that either there is a God (which it sees as a perfectly tenable position) or that natural selection is an inherent property of 'nature'. I know that our brains are conditioned to see patterns where one exists, but I find the former prposition more believable than the latter.

Anonymous said...

Evolution = duck can become dog through time plus chance, or punctuated equilibrium given enough systemic stress.

evolution = golden retriever can become newfoundland

The first is a religious notion, requiring faith in the absence of scientific verification, the second does not require a discussion of theology.

Anonymous said...

1st, I offer my good wishes to Dr. H for a happy outcome to his surgery.

i don't see present evolution theory adding to our understanding of life or God. Life is imbedded in the periodic table of the elements. they evolved from subatomic particles and so on.
the universe is the unconscious; life is the conscious. the various combinings of the foregoing elements is the universe's way of establishing consciousness and learning about itself. and perhaps through this learning process uncover the true mystery...the mystery of its own existence which may lead us to a common understanding of God. it will take time.