Evolution and Chance

In this blog, I have discussed quantum physics and I have discussed the Darwinian explanation for evolution. These two theories may seem utterly removed from each other, may seem to deal with almost completely unrelated phenomena, but both are alike in one important respect. They both put probability, chance, at the centre of their respective systems. I have discussed quantum physics before in this blog. In tonight's post I am going to discus evolution again and will return to quantum physics towards the end. I worry that this post may end up a little dry, but bear with me anyway.

The orthodox Darwinian explanation for evolution is quite simple, so simple it can be summarised in a paragraph. We have a population of organisms that are physically very similar and breed with each other, a species. These individuals carry a string of DNA, a genetic code, in the nuclei of their cells (the same code in every cell). Occasionally an individual is born with a slightly different genetic code than that which it could have inherited from its parents. This is known as a mutation. Mutations occur randomly. Almost always the mutation is deleterious to the survival of the organism, but occasionally it is beneficial, resulting in a longer life span and more progeny than its unmutated compatriots. Over time (therefore) the mutation (or adaption) spreads through the population as a whole, causing either the entire species to evolve incrementally or a new species to incrementally emerge. I believe this is a fair summation of the Darwinian argument as it is presented today. Although I feel sure that many evolutionary biologists would criticise this summation as being too simplistic, it is adequate for my purposes in tonight's post and is not just a straw man.

At the centre of modern Darwinism is the idea of a chance mutation. Darwin himself didn't know about DNA and didn't propose the idea of mutations – rather he said that variation existed among members of the same species and that nature 'selected' the fittest individuals. He didn't explain the cause of this variation or how novel changes could appear. It was modern Darwinists who introduced the idea of chance mutations. If we accept the modern Darwinian orthodoxy limned above, we might be inclined to believe that mutations are occurring all the time. How else could evolution occur? How else could variation come into existence? What I am going to argue however is that the standard Darwinian explanation fails because the likelihood of beneficial mutations occurring with the frequency they would need to for evolution to happen is so remote that we need some kind of additional mechanisms to account for it.

If we wished to defend modern Darwinism, it would be helpful to know how often mutations arise in a species. According to the Internet, the global human population increased by close to one hundred and thirty million people last year. How many of those babies were born with small mutations? Of course, no one knows. We could make an estimate, perhaps, if we mapped the genomes of a thousand babies, compared those genomes to the genomes of their parents, and then extrapolated the results. Or we could do the same thing with lab rats (this might be easier). However we carry it out, what we wish to find is the mutation rate, how often mutations occur, or, to put it another way, the probability that an infant will be born with a mutation. In fact, I suspect mutations (rather than recombinations of parental DNA) are extremely uncommon. We hear occasionally about rare genetic diseases but we almost never hear about unique genetic diseases. This suggests to me that the mutation rate, at least among humans, is incredibly low.

Even if mutations do occur, most will either be detrimental to the survival of the organism or will have no detectable effect on the organism. We are interested only in advantageous mutations because it is only advantageous mutations that will spread through the population over time and result in the evolution of the species. Yet the possibility of a mutation being beneficial rather than detrimental or undetectable is also incredibly low. According to Stephen Meyer (see "Mathematical Challenges to Darwin’s Theory of Evolution" on Youtube) the probability of a string of codons on DNA coding randomly for a useful protein rather than gibberish is miniscule. (Note: the four participants in this clip come across a little as crackpots but their arguments are good.) A third factor comes into play. If a pigeon is born with a small beneficial mutation, is, say, born a little smarter than its fellow pigeon rivals, but is eaten by a cat when it is still a fledgling or before it has had an opportunity to reproduce, the mutation dies with it.

What we are interested in is the probability that a mutation will occur that will spread through a population over time until every member of the population carries the same mutation. This probability is the mathematical product of three other probabilities: the probability of a mutation occurring in the first place, the probability of it being beneficial rather than detrimental or invisible, and the probability that the individual who bears this mutation will survive long enough to reproduce as will its offspring. This product is extraordinarily tiny. And this is just the probability of one small incremental change rather than the enormous series of incremental changes that would enable an animal like a hipopotamus to evolve into a dolphin. Now, evolutionary biologists like Richard Dawkins would argue that even though such evolution is extraordinarily unlikely to occur in a short span of time, it is not just possible but highly probable to occur if the time span given is long enough (say four billion years) and if there are sufficient organisms around. However, I doubt this – I suspect that even four billion years is not long enough.

The argument is simple. Suppose we work out that the chance of a random mutation occurring that is beneficial and will spread through a whole population is one in a billion trillion. And we then find out that such mutations occur one time in a million. We would then be forced to conclude that such mutations aren't entirely random, and we would need to posit an additional mechanism as the cause of them rather than simply ascribe them to blind chance by itself.

This argument could be called the argument from improbability. In this blog I have also presented another argument against the Darwinian orthodoxy (in the post "On Evolution). In this previous argument, somewhat related to the Irreducible Complexity argument associated with Behe, I concluded that, when a significant mutation occurs, it must occur to a number of organisms existing in the same vicinity at the same time. I wish now to present a third argument against the modern Darwinian orthodoxy. We live in an era in which the fashionable school of thought in the social sciences is evolutionary psychology, a discipline I have criticised before in this blog. Although evolutionary psychologists don't seem to want to use this word, they are interested in instincts, behavioural adaptions. For instance, an evolutionary psychologist might say that people are born with an instinctive fear of snakes, an instinct that is genetic. He or she might imply that people are born with a 'fear of snakes' gene. Somehow we go from DNA to a protein, then to an arrangement of neurones in the brain, then to an aversion to snakes. I don't comprehend this move. I simply can't understand how a fear of snakes could be encoded in DNA, in a sequence of bases.

And now it's time to bring in quantum physics. As I argued in the posts on probability and Schrodinger's cat, quantum physics introduces a new concept – objective uncertainty. In a determinist world,  people can be uncertain but reality is certain; in the quantum world, however, reality is itself indeterminate, uncertain. For example, if we fire an electron through a slit at a detector, it diffracts and there are a range of possible locations it can arrive at – and we have no way of predicting precisely where. In those posts, I argued, in effect, that everything is connected to everything else, that non-local hidden variables are at play, and I speculated that higher intelligences may operate through the quantum world. This might apply to evolution. I am not arguing that evolution didn't happen. Rather I wish to suggest that mutations are not wholly random and that some kind of intelligence may be working behind them or through them, bringing them about.

The argument about Darwin is often framed as a dispute between die-hard materialists and Christian fundamentalists. The Darwinists believe that evolution has got rid of God; the Christians see arguments against Darwin as bolstering the case for Christianity. Both sides are dogmatists. I am neither a Christian nor a Darwinist. For example, although I suspect some kind of higher intelligence may be at work in the world, and see evolution as evidence for this. I don't necessarily believe this intelligence to be benevolent or loving. This is why I like Rupert Sheldrake. Sheldrake is a practising Angican but not a devout Anglican. Although he talks about telepathy, clairvoyance, and precognition, he doesn't ever invoke God as an explanation for things. His theory of 'morphic resonance' is a third way between the dogmatisms of the Christian fundamentalists and the orthodox Darwinists. I am not sure that I believe in 'morphic resonance'. But Sheldrake's view that consciousness is everywhere and that everything is connected to everything else resonates with me.

It may be frightening to give up our convictions. But sometimes the truth involves recognising that no one knows the truth.