Friday, June 29, 2007

More on "The Edge of Evolution"

It's hardly surprising that Behe's book, "The Edge of Evolution" (EoE), should have aroused the mixed anger and ridicule of the darwinist community. Had he done no more than say there were limits to what evolution could achieve, he would have been accused of being typically ID and saying something that was unfalsifiable. Where in "Darwin's Black Box" he said that the evolution of irreducibly complex systems was impossible, the response had several contradictory strands - one being that his claims were unfalsifiable, others being attempts to falsify them by proposing evolutionary mechanisms that overcame the irreducible complexity.

But in EoE, Behe ups the ante by saying to his readers: forget irreducibly complex biochemical machines. The edge of evolution is actually much closer than that. Evolution is pretty much incapable of producing any complex protein interactions. Obviously, if what he has to say has any credibility whatsoever, then the whole concept of undirected evolution would be seriously undermined. So opponents of the concept of intelligent design are bound to do what they can to ensure that what Behe says is not treated with any credibility whatsoever. Even engaging in a meaningful way with the issues he has raised would do them too much damage - better for them to pretend that nothing of any significance has been said. I can understand this - as (I believe) Scott Adams put it in a Dilbert cartoon, the noise you hear is "a paradigm shifting without a clutch".

However, there is a real issue here which the responses to EoE from darwinists seem to have skated around. The HIV and the malarial parasite have been studied in greater depth than any other organism. Thanks to the large populations in host organisms and high rates of reproduction in both cases, they ought to be excellent examples of evolution in action. If we are going to be able to learn anything at all about how evolution actually works in real life, then surely we should see it in action in both.

So what exactly do we see?

Behe says, basically, not much at all. HIV continues to work in the same way that it did when it was first observed; despite the billions of mutations (in a single infected human, most possible single and dual mutations are statistically likely to be explored every day), the virus has no more weapons in its armoury than when it first appeared. The same goes for the malaria parasite. Again, billions of organisms mean billions of opportunities for evolution to try new options. But do we see them? We see single mutations that achieve the short-term goal of providing resistance to treatments - but since once the treatment is withdrawn, this mutation disappears from the population, resistance to this treatment seems to be achieved with a reduction in general fitness (Behe likens this to "trench warfare" rather than an "arms race" - burning a bridge to prevent the advance of an enemy, rather than the appearance of a fantastic new weapon). The same applies to resistance to malaria provided by mutations in humans - in all the years and all the cases of malaria that have been seen, the number of appearances of mutations that provide increased resistance to malaria without a general reduction in "fitness" otherwise is very small.

The observations that Behe makes are significant, but perhaps they are capable of alternative explanation. For example, if both malaria and HIV fit very well in their ecological niche, could it be the case that there is little pressure from natural selection driving change? It has been observed before that the fossil record is one of stasis accompanied by sudden change, rather than gradualism, and we also see some species today that have survived unchanged in the fossil record for hundreds of millions of years. The fact that HIV and the malaria parasite survive largely unchanged through the passing of generations would suggest that the physiological stasis is matched by genetic stasis.

However, this is of limited value as a response to Behe - firstly, because it means that we can't see evolution in action in the most obvious natural examples, which will lead us to wonder if we can ever expect to identify it, and if not, whether it is itself unfalsifiable - and therefore, no more scientific than Intelligent Design, if that is the charge levelled against it. Secondly, because the environment in which HIV and the malarial parasite are present in does bring evolutionary pressures to bear on them. In an "arms race" evolutionary scenario, surely the sickle cell mutation which brings a measure of protection from malaria to some humans would have been met at some stage with a mutation that could overcome it. It isn't conceptually impossible either that HIV could develop and utilise a different mechanism to invade host cells, allowing it to overcome the resistance present in some humans - and yet it hasn't.

I've no doubt that this won't be my last word on the matter ....