(Lamarkian?) Epigenetics is far faster than the lone neo-Darwinian mechanism ...
But an epigenetic hypothesis only defers the Darwinian question.
Epigenetic Lamarckism works like this, as I understand it. You have, external to the DNA, a switch, a toggle, affecting DNA expression. The position of the switch is inherited, but can be flipped as a response to the environment.
So, let's imagine an epigenetic explanation for the koala diet. What we would need is some sort of switch that toggles between eating like a wombat and eating like a koala, which is flipped into koala mode by some exterior stimulus such as, I dunno, smelling eucalyptus. OK, we now have a nice simple explanation for how and why koalas eat eucalyptus. But we have also saddled ourselves with rather difficult problem:
how did the two dietary options and the switch between them evolve? So we haven't really made things any simpler.
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Imagine an alien who thinks that humans are stupid. So when he finds a bicycle, he declares that it's way too sophisticated to have been designed and built by humans unaided. No, he explains, it must have been designed and built by some sort of industrial robot, and all the poor dumb humans did was perform the relatively simple task of pushing the big red
ON button on the front of the robot --- and pushing buttons, he smugly explains, is well within their primitive capacities ...
Well, he hasn't made things any easier for himself, has he? Because now he needs to explain how those dumb humans who're too stupid to build a mere bicycle managed to produce the robot.
Edited by Dr Adequate, : No reason given.