Evolutionists claim that transmutation (though they wouldn't use that word) has occurred through a combination of mutations and selection. This is called neo-Darwinism. Mutations are thought to create the genetic fodder for a potential selective advantage. The environment will then come into play to dictate whether populations with the new characteristic have a survival advantage over those without it.
An immediate problem arises in that this evolutionary mechanism must explain all features of all creatures in every environment. But how can the fin of the fish and the legs of the crab both be explained by water? The long nose of the anteater and the short nose of the monkey cannot be explained by their ant food. The short neck of the elephant and long neck of the giraffe cannot both be explained by leaf food. A mechanism that explains everything, including contradictions, explains nothing.
The normal rebuttal to these objections is to say that evolutionary changes are very small and incremental and thus more probable. So to explain something like the eye coming into existence through chance mutations, it is reduced to its more manageable (from an explanatory standpoint) parts: lens, cornea, lids, retina, and so on. Then stories are devised as to how each of these parts evolved. But the problem has not been left behind. The survival advantage of each incremental step must be detailed.
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