I’ve been reading Yuval Noah Harari’s best-seller Sapiens and I think it is very good. My own forthcoming book Prehension is in the same area, though I deal with human evolution before culture got started. One thing he emphasizes is that H. Sapiens once shared the planet with several other human species–Neanderthals, H. Erectus, Denisovans, and others. These are all, sadly, extinct. This is a great pity for many reasons, one of which is that we can never investigate their psychology. Would we find various cognitive limitations in our fellow human species? Might they exceed us in some areas? It seems likely that we would conclude that some areas are off limits to their understanding–that there are mysteries-for-Neanderthals. There is certainly no guarantee that all these species would be intellectually equal. Maybe they would conclude that there are mysteries-for-Sapiens! In any case, the question of mysteries and cognitive limits would be much helped if these species had not gone extinct. As it is, it is easy for us to see ourselves as quite discontinuous with other species intellectually–and hence nurture illusions of omniscience.