Hi Percy,
Perhaps this reply should go in the
Why creationist definitions of evolution are wrong, terribly wrong. thread ...
Darwinists say that evolution is explained by the selection of phenotypic traits by environmental filters.
You will note that the book is titled "What Darwin Got Wrong" but the argument is about what "Darwinists say" not Darwin?
In effect, the mechanism of trait transmission it postulates consists of a random generator of genotypic variants that produce the corresponding random phenotypic variations, and an environmental filter that selects among the latter according to their relative fitness.
This appears to be their definition of what evolution involves. Like the creationist definitions, it is missing some critical aspects.
We should stress that every such case (and we argue in our book that free-riding is ubiquitous) is a counter-example to natural selection. Free-riding shows that the general claim that phenotypic traits are selected for their effects on fitness isn't true. The most that natural selection can actually claim is that some phenotypic traits are selected for their effects on fitness; the rest are selected for... well, some other reason entirely, or perhaps for no reason at all.
What is missing here is that it is not survival of the fittest, but non-survival of the unable to survive, and that selection removes non-fit traits. Thus many neutral and slightly deleterious traits continue to be passed from generation to generation.
But the effects of endogenous structure can wreak havoc with this theory. Consider the following case: traits t1 and t2 are endogenously linked in such a way that if a creature has one, it has both. ... But it is perfectly possible that one of two linked traits is adaptive but the other isn't; having one of them affects fitness but having the other one doesn't. So one is selected for and the other "free-rides" on it.
And as long as neither are net deleterious both will continue -- selection always operates on the
whole phenotype, not on individual aspects of it, so this is no different from neutral mutations getting a "free ride" by not being selected against. This just increases the amount of variation in a population, and gives natural selection a larger playing field when conditions change. Certainly the "free ride" traits do not lead to new species the way that traits subject to natural selection have been known to do.
What we have here is a misunderstanding of how evolution works.
Crucially, however, the evolutionary process in such cases is not driven by a struggle for survival and/or for reproduction. Pigs don't have wings, but that's not because winged pigs once lost out to wingless ones. And it's not because the pigs that lacked wings were more fertile than the pigs that had them. There never were any winged pigs because there's no place on pigs for the wings to go. This isn't environmental filtering, it's just physiological and developmental mechanics.
So because wings cannot evolve in one big "hopeful monster" whack like creationists seem to think, the "
origin of species by means of natural selection, or the preservation of favoured races in the struggle for life" is wrong?
Pretty poor logic for a philosopher.
This shows (no great surprise) that creationists are not alone in making mistakes about evolution based on a poor understanding of what evolution entails.
Enjoy.
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