Trading instincts for intelligence

I thought the other day about how animals know what to eat and how to find it, seemingly from birth. Do animals accidentally eat poisonous or harmful things? It doesn’t seem like it. But we humans, we don’t know how to eat, how to catch food, how to prepare it, until we’re taught. We don’t know how to do most things until taught. I wonder, if we’d even figure out how to have sex without being told…

Is that the cost of high intelligence? Perhaps there is no more room in our head for all that instinctual knowledge that other creatures seem to have. Or, maybe once we got intelligent enough to learn it all, the selective pressure to keep the instincts was removed, and they were bred out of us over the eons.

I wonder if the reverse could ever happen, and we could lose our intelligence in favor of instinct…