In particular, they say animals show use of language and tools. They recently even claimed use of recursion:
Time and again, it seems, research has revealed crows performing some cognitive task that defies our expectations. Now, a new paper claims the birds can understand a certain kind of pattern, displaying an ability that scientists once thought was unique to humans.
Researchers tested whether crows can grasp the concept of recursion, which they define as “the process of embedding structures within similar structures” in their paper published in November in Science Advances.
Humans use recursion in language when we embed one clause within another to form a complex sentence, writes Scientific American’s Diana Kwon. For example, if a human says, “The ball the bat hit flew,” they’ve nested the clause “the bat hit” inside of “the ball flew.”
Now they say, after decades of observing chimpanzees, an example of a referential gesture has been recorded.
The video shows a chimp playing with a leaf. The paper calls it "leaf grooming", but it is unknown why a chimp would groom a leaf. At one point, the chimp appears to show the leaf to another chimp.
That's it. A chimp shows a leaf to another chimp, and it is the biggest cognitive advance anyone has ever seen in chimps, who are supposed to be our closest animal relatives.
Even still, the evidence is ambiguous. Nobody knows why the chimp was playing with the leaf, or why he would show it to another. Maybe he was trying to give it away, or just playing, or just confused.