So, might this not indicate that chimps are slowly but surely evolving toward a higher intellect, as a harsh environment selects against the dumb?
If there were no matriarchs capable of grasping a concept like hunting with weapons, instead of bare hands, 100 years ago, does that mean that they might unravel stone sharpening in 500 years?
The idea that human civilization might witness the true, literal evolution and flourishing of a second earthly intellect in species outside of humans is really exciting.
Maybe it's not evolution in action. Maybe chimpanzees of today are no smarter than 100 years ago. Maybe it takes 50 years of trial and error amongst social groups to learn such a skill, and then retain it across generations by teaching. Maybe tools like this have been invented and lost many times by various chimpanzee social groups over the past few centuries.
But it would still be really cool if this were representative of the emergence of a generation of apes, palpably smarter than those of, say, the 19th century.