The Ancestor’s Tale: A Pilgrimage to the Dawn of Life by Richard Dawkins
Richard Dawkins is a scientist. Or rather, he was a scientist 40 years ago when, as a postgraduate student, he assisted Niko Tinbergen with his research into animal behaviour. But early in his career, in 1976, Dawkins enjoyed a huge success with his first book, The Selfish Gene, and this led to a sea-change away from being a practising scientist to becoming Britain’s best-known populariser and champion of Darwinism -– the idea that evolution is driven by the natural selection of genetic mutations.
Since 1976, Dawkins has written tirelessly on Darwinism, producing seven books and countless articles. Much of this impressive output has revolved around the single central issue of Darwinism — the issue of the improbability of life evolving by purely random processes. Anyone who has read his work during these decades will know that it is aimed first and foremost at breaking down, or at least mitigating, the seriousness of the improbability of Darwinism.
However, readers may not have noticed that his writing falls into two distinct phases. His best-known Darwinist book was The Blind Watchmaker in 1986. In this, Dawkins had two aims. First, to attack the argument from design, advanced by William Paley in 1828. If you found a watch while walking in the forest, Paley argued, you would be compelled to accept that such a complex mechanism must have been designed by some intelligence. Dawkins easily refuted this argument by pointing out that it is contradicted empirically: there are plenty of securely known examples in nature where complex structures are produced by random natural processes. The grading of pebbles on the beach is one that comes to mind. Complex though it may be, life could be another of these processes.
The second aim of The Blind Watchmaker was an extremely audacious frontal assault on the mathematics of the improbability of Darwinism. His lengthy suggestion is summed up thus:
‘My personal feeling is that, once cumulative selection has got itself started, we need to postulate only a relatively small amount of luck in the subsequent evolution of life and intelligence. Cumulative selection, once it has begun, seems to me powerful enough to make the evolution of intelligence probable if not inevitable. This means that we can, if we want to, spend virtually our entire ration of postulatable luck in one big throw . . .’
Put simply, Dawkins proposed that evolution by the natural selection of random mutations is not as improbable as it might at first glance appear. If, he said, we break down the process into smaller and smaller steps, then the improbability of each individual stage is reduced. If we choose a large number of intermediate steps, then the improbability of each step is reduced so much that it becomes within the range of improbabilities that occur practically every day. In other words, breaking evolution down into small steps converts it from an improbable process to a probable one. And, he says, it is the cumulative power of natural selection that makes this breaking down into smaller steps possible.
A very similar idea was expressed by Ronald Fisher, the geneticist, when he wrote that, ‘Natural selection is a mechanism for generating improbability.’
This is an extremely powerful and attractive argument. So powerful and so attractive that practically everyone who read Dawkins’s book bought into it and remained convinced of it for many years (many still are today).
In 1992, I pointed out in print that Dawkins’s suggestion is mathematically flawed. It is true of the probability of unrelated events (such as tossing a coin) but is untrue of related events such as the cumulative natural selection of random genetic mutations. Indeed it is the cumulative nature of natural selection (which Dawkins proposed as its greatest strength) that is in fact its greatest weakness from the point of view of its improbability.
The need for genetic mutations to occur in the correct sequence to feed into the one-way accumulation of natural selection at just the decisive moment is the very factor that makes it so increasingly improbable as a natural mechanism.
From a mathematical viewpoint, the probability of life evolving via the natural selection of ten big mutations is exactly the same as the probability of life evolving via ten thousand small mutations, if the order in which the mutations must occur is taken into account (and, of course, the order is crucial).
Although making no public comment, Dawkins evidently took this point on board, because he dropped the claim from all later books and concentrated instead on attempting merely to mitigate the improbability of Darwinism by other means. The philosophical tool he fell back on to achieve this goal is that old favourite, the anthropic principle. We must have evolved by the selection of mutations because we are here, aren’t we? How else could it have happened? However improbable it may be that natural selection could lead to life, the improbable must have taken place. There is no other rational scientific explanation.
In keeping with the retrospective thinking central to the anthropic principle, Dawkins has written his later books from a backwards-looking point of view: River out of Eden, Climbing Mount Improbable, Unweaving the Rainbow and, now, his latest, The Ancestor’s Tale.
However, in deploying the anthropic principle in this way, Dawkins seems not to have recognised the series of important scientific developments that have taken place over the past four decades. When he wrote The Blind Watchmaker in the 1980s, Darwinism appeared to be securely buttressed by mountains of detailed natural observations that supported its main contentions: observations such as the divergence of Galapagos Finches, industrial melanism in moths, and vestigial organs in the human body. With all this evidence, Darwinists could feel confident that they were on sure ground in general, even if matters of detail were not yet fully worked out. But while he was tirelessly recycling arguments from the anthropic principle, Dawkins failed to notice that this ‘evidence’ was melting away around him, like snow on a spring morning, thanks to better observation and clearer thinking.
Through the work of Peter and Rosemary Grant, for example, we now know that there are not 13 divergent species of finch on the Galapagos islands but a single species with many varieties – just like the many varieties of dog. We know, too, that ‘industrial melanism’ has no relevant connection to evolution or natural selection but merely to shifting balances of population. And we know that organs previously thought to be ‘vestigial’ do in fact have important functions of which we were simply ignorant. Dozens of similar examples can be given. We now know also that, far from being ‘a mechanism for generating improbability’, natural selection is a tautology lacking any scientific content.
Dawkins has failed to notice that this receding tide of fact has left him marooned alone atop Mount Improbable and that what was once a useful tool of explanation for a complex web of facts is now no more than empty sloganising.
As I sit and read Dawkins continual cry of ‘It must have happened this way – what other rational explanation is there?’ I am sometimes almost tempted to agree with him. But then I think of Antoine Lavoisier, secretary of the Academie des Sciences who disbelieved in meteorites and who told his fellow academicians, ‘Gentlemen, stones cannot fall from the sky, because there are no stones in the sky.’
A wider scientific perspective -– a very much wider perspective -– was needed before Lavoisier and his contemporaries could grasp how it can be simultaneously true that there are no stones in the sky, and yet stones can and do fall from the sky. Evolutionary biology –- at least the Dawkins end of it — is still stuck in the mire of Lavoisier-style ignorance. Books like this merely popularise that scientific ignorance.
This review of The Ancestor’s Tale was originally published in Network, the magazine of The Scientific and Medical Network.