A lot of it comes from communication. We don't know how intelligent some of these things are simply because we can't communicate with them.
For apes and gorillas we can communicate. We've taught them sign language so we know hands down in terms of language we beat them. But for dolphins and octopi, we just don't really know.
For apes and gorillas we can communicate. We've taught them sign language so we know hands down in terms of language we beat them. But for dolphins and octopi, we just don't really know.