I recently read Arthur Koestler's 1967 book The Ghost in the Machine. In it, Koestler criticises the neo-Darwinian theory of evolution—beneficial random mutations preserved by natural seleciton—as insufficient to explain the formation of complex forms like eyes and eggs. The issues Koestler has with the theory are ones that I've been trying to wrap my head around since before I read the book, but I'm aware that:
a) the book is half a century old;
b) Koestler was not a biologist or scientist; and
c) neo-Darwinian theory/the modern synthesis seems to have stood the test of time
so I'm wondering how accurate Koestler's account of the theory is, and if he is wrong what the retorts to his claims are. Here are two examples he gives of complex forms:
[The giant panda] has on its forelimbs an added sixth finger, which comes in very ‘handy’ for manipulating the bamboo-shoots which are its principal food [but] that added finger would be a useless appendage without the proper muscles and nerves [and t]he chances that among all possible mutations those which produced the additional bones, muscles and nerves should have occurred independently are of course infinitesimally small.
The decisive novelty of the reptiles was that, unlike amphibians, they laid their eggs on dry land...[b]ut the unborn reptile inside the egg still needed an aquatic environment...[i]t also needed a lot of food...[s]o the reptilian egg had to be provided with a large mass of yolk for food, and also with albumen—the white of egg—to provide the water. Neither the yolk by itself, nor the egg-white itself, would have had any selective value...[e]ach change, taken in isolation, would be harmful, and work against survival.
Instead of random mutations and external selection, he suggests that ‘internal selection’ works at all levels, from chemical upwards, to correct ‘misprints’ long before the developed organism is exposed to any sort of external selection. The implication that there must therefore be some plan towards which embryonic development works is supported by two examples:
the growing eye-bud of the embryo is an autonomous holon, which, if part of its tissue is taken away, will nevertheless develop into a normal eye
[the fruit fly has a recessive gene that when paired with another in a fertilised egg will produce an eyeless fly.] If now a pure stock of eyeless flies is made to inbreed, then the whole stock will have only the ‘eyeless’ mutant gene, because no normal gene can enter the stock to bring light into their darkness...within a few generations, flies appear in the inbred ‘eyeless’ stock with eyes that are perfectly normal.
His other main point is that evolution takes a zig-zag path, evolving down until reaching an evolutionary dead-ends before retracting to ‘an earlier or more primitive, but also more plastic and less committed stage—followed by a sudden advance in a new direction’. For example:
[A]mphibian...ancestry...goes back to the most primitive type of lung-breathing fish; whereas the apparently more successful later lines of highly specialised gill-breathing fishes all came to a dead end.
...the human adult resembles more the embryo of an ape than an adult ape
Is Koestler's science just faulty, or are these valid criticisms that've been resolved since?