Lee Spetner, author of Not By Chance! and The Evolution Revolution, explains why natural selection can't produce macroevolution.
For the grand process of evolution to work, long sequences of “beneficial” mutations must be possible, each building on the previous one and conferring a selective advantage on the organism. The process must be able to lead not only from one species to another, but to the entire advance of life from a simple beginning to the full complexity of life today. There must be a long series of possible mutations, each of which conferring a selective advantage on the organism so that natural selection can make it take over the population. Moreover, there must be not just one, but a great many such series.
The chain must be continuous in that at each stage a change of a single base pair somewhere in the genome can lead to a more adaptive organism in some environmental context. That is, it should be possible to continue to climb an “adaptive” hill, one base change after another, without getting hung up on a local adaptive maximum. No one has ever shown this to be possible.
Now one might say that if evolution were hung up on a local Maximum, a large genetic change like a recombination or a transposition could bring it to another higher peak. Large adaptive changes are, however, highly improbable. They are orders of magnitude less probable than getting an adaptive change with a single nucleotide substitution, which is itself improbable. No one has shown this to be possible either.
Moreover, as I have noted in my book, the large mutations such as recombinations and transpositions are mediated by special enzymes and are executed with precision - not the sort of doings one would expect of events that were supposed to be the products of chance. Evolutionists chose the mechanism of randomness, by the way, because we can’t think of any other way beneficial mutations might occur in the absence of a law that might govern them. Genetic rearrangements may not be really random at all. They do not seem to qualify as the random mutations Neo-Darwinists can invoke whenever needed to escape from a local adaptive Maximum.