This is a book about evolutionary convergence, arranged for the general reader. It is illustrated sparingly with black-and-white diagrams and pictures. There are copious end notes and references for any who might like to pursue the subject on their own, although they might need a university library to do it in. Convergence in evolution, an apparently widespread phenomenon, is a process whereby the same or similar structural or physiological solution evolves repeatedly and independently among different organisms and in different eras, in response to similar environmental pressures. The repeated evolution of some form of eye is probably the best known example. This used to be the stock in trade for evolutionary sceptics, who would mock honest biologists with "what use is a half-evolved eye, answer me that". Conway Morris gently demonstrates that there is no such thing as a "half-evolved" anything, since evolution has no plan. There is however something called "inherence". This is more than a restatement of the truism that, if something evolved in a given species of organism, the capacity to do must have been there already and can often be discerned in the organism's distant ancestors. The stronger form of inherence says that, given the right genetic material and the right environment and enough time, you can make informed predictions about what is going to happen. Both convergence and inherence seem to be hugely controversial topics among biologists and Conway Morris gives us a flavour of this in his quotation from sources that use words such as "remarkable" and "surprising" when describing the observed phenomena of convergence, as if some orthodoxy is being challenged. Quite what the orthodoxy was or the nature of the controversy never really emerged, or this reviewer missed it. Instead, in the closing chapter, we were treated to another dispute altogether: the problem that some religious writers have in reconciling their beliefs with the robust edifice of the Theory of Evolution. This may or may not be a worthwhile subject of debate, but evolutionary convergence seems to have little bearing on it. Moreover Conway Morris only skates over the subject, with quotations from C.S. Lewis and G.K. Chesterton and a more recent writer called J.C. Greene, and he gets off a couple of broadsides in the direction of Richard Dawkins.
So we really never found out what the fuss was about with convergence and we could have had rather more detail on the daft things theologians and biologists can say about each others' world view, when they don't know much about it. Finally, the ocean of truth that Conway Morris was standing beside received no mention at all. The question is whether convergence in evolutionary biology is just one example of convergent processes in reductionist, chaotic systems with memory but no foresight. How about human systems of government, legal principles, political economy, trends in aesthetics? Conway Morris claims that, given the right environment, the living system of the type we have here on Earth (he would go further and say the only type on offer) will "inevitably" produce "mammal-ness" and consciousness. This sounds like historical determinism. Is the main difference between convergence in evolution, as observed by Simon Conway Morris, and the logic of history, as observed by Oswald Spengler in Decline of the West, just one of time-scale? Did Conway Morris not notice this unexploded bomb, or did he dig it up, take fright and bury it again?