He added: “Interestingly, the individuals that solved the problem were not just spitting randomly. Instead their behaviour seemed very goal directed and could not be explained by trial-and-error approach.
“In addition, instead of spitting, one young male chimpanzee once urinated into the tube in order to raise to water level and bring the nut into reach.
“Obviously, he understood that liquid is needed to solve the problem – regardless where it’s coming from. That was not only funny but scientifically interesting since it can be seen as a manifestation of cognitive transfer.”