Science
In reply to the discussion: Humans are not smarter than animals - we just don't understand them [View all]hunter
(38,317 posts)They contemplate what other animals think.
It's a useful talent for getting along with other animals in their pack (including humans), for avoiding enemies, and for hunting.
A good shepherd dog expends a lot of mental energy figuring out the minds of sheep, a good pig hunting dog expends a lot of mental energy figuring out the minds of pigs. The inclination is there by "instinct" but the skills are developed by experience, which includes quite a bit of contemplation of how other animals think.
As social hunters we ourselves are very similar to dogs in that respect. Contemplating the minds of other animals is a part of our own mental toolkit.
Humans are remarkable for our writing and sophisticated storytelling. These language processing talents are the foundation of our modern civilization.
I suspect if we could add this "language module" to the minds of any social species we'd have to call them intelligent.