What we call intelligence is largely a genetic trait. Otherwise I’d be able to have this conversation with my dog.

I think the main point is, if the genetic predisposition to what we call intelligence does not positively affect the reproduction rate, the process of evolution could phase it out at any time. The “goal” of evolution is adaptation in order to reproduce. The intelligence is not THE strategy to adapt, its A strategy. It could be replaced by something else, like faster reproduction rate, or the ability to survive in harsh environment without a need for clothes, housing, and medicine.