Not supernatural intelligence - ours.
Mel kindly alerted me to Fisherian Runaway recently and it struck me that a lot of evolution could driven by methods outside the classic "survival of the best adapted [to the environment]".
I'm floating an idea here, so please bear with me: I guess we can co-opt animal intelligence into the survival paradigm, but a more intelligent discussion (and refutation of the supernatural!) could perhaps be had if we allow for the separation of purely natural biological effects (of which there are many) and other effects which are directed by other forms of selection.
I can't find any sensible biologist suggesting that plants have intelligence - they just didn't need any so they're evolving in a classic undirected chaotic line. Higher animals, however, are quite capable of making "informed" decisions; and the highest of all (us, arhem) are really messing it all up.
I'm don't want to argue the rights and wrongs of this, just accept that we do.
It struck me one of the problems extolling evolution to an evolution denier is they see [supernatural] design in everything - even though it's clear to us that the designer is only nature "herself". A better examination of the sentient affects on evolution could, perhaps, better explain the ludicrous theses proposed by Perry Marshall and others.