That is the question that some scientists are coming back to. There is a test to see if an animal is self-aware: the mirror test. First scientists put a mirror in the environment so the animal can get familiar with it. Then they put a mark on their body that they can only see in the mirror. It’s evidence for self-awareness if they look in the mirror and then touch that part of their body.
Human can do this when they’re about 2 years old. Many other primates also pass. So do elephants, and 1 bird, the magpie. Some scientists disagree that they elephants and magpies really passed.
And now, there’s another possible species that might be considered self-aware: The cleaner wrasse. This is an intelligent, very social, fish that lives in coral reefs. Researchers gave some the mirror test, and some of them passed. The injected a bit of color under the scales around the “chin” of the fish, and after seeing their reflection, they tried to scrape their chin on the sandy bottom, something they do to remove irritants.
The researchers had a lot of trouble getting their paper published, possibly due to resistance in the scientific community to admitting that a fish can be self-aware. Many scientists doubt the results of this experiment, thinking that the fish’s behavior doesn’t show self-awareness.
Just what this experiment means has yet to be decided, but it’s very interesting.