I am not sure that I agree with this statement; there is a gorilla in captivity named Koko who has learned sign language and how to use a computer and taught her son to use a laptop. She has expressed empathy and understanding and self awareness, including her sadness when Robin Williams committed suicide.
I have watched chimps both in captivity and in the wild through the lens, and I don’t know that we are necessarily smarter than them so much as we have a need to express ourselves differently; we actually share several traits with them besides genetic ones, one of them being the allegory of the chimp who reached into a bamboo trap for a nut and couldn’t release himself because he refused to open his fist.
We still don’t know where conscious awareness comes from, although the Astonishing Hypothesis suggests it is a collection of glial tissue, protein matter, and nerve cells, and there is a question of whether or not prions have conscious intelligence and awareness.
So, are we smarter than a chimp, if we are not smarter than a prion?