Both Turing and Von Neumann machines (and the lambda calculus by Church) were designed to be minimal implementations that were still powerful enough to be prova

Both Turing and Von Neumann machines (and the lambda calculus by Church) were designed to be minimal implementations that were still powerful enough to be provably complete in a mathematical sense. Mother Nature is under no such constraints: she happily constructs massively parallel "computers" with millions of global variables, each being written to by every core. That human minds cannot debug such systems is not Her problem. The only constraint is if it works, and it does.