Neo-Darwinist ‘fitness’ 

But does neo-Darwinism's redefinition of the theory fare any better? The modern synthesis began in 1930 with the widely acclaimed book The Genetical Theory of Natural Selection by the British geneticist and mathematician Sir Ronald Fisher. Here, instead of trying to establish what makes an individual creature best fitted to survive in a changing environment, he looked at the population as a whole. The sole criterion for fitness, he wrote, is the number of offspring left by particular creatures within the population, without reference to their way of life. 

Whether this has got rid of the tautology is still debated. Sir Peter Medawar and Stephen Gould think yes (panel 17). But Conrad Waddington of Edinburgh University said at the Wistar symposium: 

The theory of neo-Darwinism is a theory of the evolution of the changing of the population in respect to leaving offspring and not in respect to anything else. Nothing else is mentioned in the mathematical theory of neo-Darwinism. It is smuggled in and everybody has in the back of his mind that the animals that leave the largest number of offspring are going to be those best adapted also for eating peculiar vegetation, or something of this sort; but this is not explicit in the theory. All that is explicit in the theory is that they will leave more offspring. There, you do come to what is, in effect, a vacuous statement: Natural selection is that some things leave more offspring than others; and you ask, which leave more offspring than others; and it is those that leave more offspring; and there is nothing more to it than that. The whole guts of evolution - which is, how do you come to have horses and tigers and things - is outside the mathematical theory. ¹⁶ 

We have come full circle. To put it at its mildest, one may question an evolutionary theory so beset by doubts among even those who teach it. If Darwinism is truly the great unifying principle of biology, it encompasses extraordinarily large areas of ignorance. It fails to explain some of the most basic questions of all: how lifeless chemicals-came alive, what rules of grammar lie behind the genetic code, how genes shape the form of living things. 

But if natural selection is found wanting, are the alternatives any better? As we shall see now, there is no shortage of people who think so.