Metaphysics is basically a question of axioms. Reasoning can't get off the ground without some unproven assumptions. We can certainly talk about our assumptions without proving them!
I would argue that most axioms used by thinking brains ultimately derive from evolutionary processes. But again, this is different from proving them, and brain development is far from simple.
I'd argue that in practice everyone believes in everyday common sense - even philosophers who claim to follow some philosophy that's radically contradictory to it (in a similar sense to the economist's notion of "revealed preferences"). So someone who relies on a novel set of axioms is relying on a bigger and more dubious foundation than someone who's able to "Neurathian bootstrap" starting with just the everyday common sense that we are already all relying on.
I would argue that most axioms used by thinking brains ultimately derive from evolutionary processes. But again, this is different from proving them, and brain development is far from simple.