[Nasrudith]

Photosynthesis as an argument is more 'it is possible that quantum effects have a place here' - that said it is a long leap given that our retinas are technically quantum just by processing particle-wave dualities. The quantum /computing/ is what is relevant to proof of there being any 'special sauce' to the human brain vs just a bunch of parallel processing power.

Essentially the quantum effects are necessary for a quantum consciousness but are definitely not sufficient. Personally I can see one way to make that link which is quite a long-shot.

Given what little I know from quantum computing and cryptography comparing parallel processing solving speed relative to problem sizes vs quantum approaches would give a theoretical basis for distinguishing the /computing/ aspects.

If human brains are able to solve progressive problems with a time increase more consistent with qubit processing than non-quantum computing combined with heuristics it would hint at quantum processing power. Needless to say that is a major tall order and would probably result in most humans failing to complete period.