Recent studies highlight that we don’t truly understand animal intelligence, possibly because we simply don’t know how to assess it:
Another failed experiment with elephants involved the mirror test—a classic evaluation of whether an animal recognizes its own reflection. In the early going, scientists placed a mirror on the ground outside the elephant’s cage, but the mirror was (unsurprisingly) much smaller than the largest of land animals. All that the elephant could possibly see was four legs behind two layers of bars (since the mirror doubled them). When the animal received a mark on its body visible only with the assistance of the mirror, it failed to notice or touch the mark. The verdict was that the species lacked self-awareness.
But Joshua Plotnik of the Think Elephant International Foundation modified the test. He gave the elephants access to an 8-by-8-foot mirror and allowed them to feel it, smell it and look behind it. With this larger mirror, they fared much better. One Asian elephant recognized herself. Standing in front of the mirror, she repeatedly rubbed a white cross on her forehead, an action that she could only have performed by connecting her reflected image with her own body.
More generally, this should make us concerned about our ability to assess the intelligence of even other humans – standardized testing might not be the best way to do it. If different species understand differently, why should it be any different within a species?