Grain floated back to her. In no time, she'd formalized the procedure. The young apes were quickest to copy her. Some adult males never caught on. Calvin goes further.
African chimpanzees shape sticks to catch termites in anthills for supper.
Females are far more creative and persistent at this technology. The same is true in selecting tools and inventing methods for cracking nuts. He offers a compelling hypothesis. Maybe it's because the female of the species spends more time with the young. And the young teach creative freedom of the mind to the old.