Monolopy on coconuts

03november2010
Source: scientias.nl; photo: J.M. Garg
A rhesus monkey has a monopoly on coconuts on the island it lives on, because it is the only one who knows how to open them. The rhesus monkey was studied for its big nose, but scientists were even more amazed by its behaviour.
Pinocchio lives on the island Cayo Santiago, a small island north of Puerto Rico, together with about a thousand other free-ranging rhesus monkeys. This population has been studied for years and most knowledge on rhesus monkeys comes from this population.
Pinocchio knows his way with the coconuts on the island. First he moves the coconut to the harbour by carefully throwing and rolling it in that direction. Rhesus monkeys usually walk on all fours so he cannot easily hold the coconut. Once the coconut is in the harbour Pinocchio picks out a cement dock, which is the flattest and hardest surface on the island. Then he throws the coconut up in the air. By standing on his hind legs, moving his arms upward and jumping a little, the coconut reaches quite high. Then it falls down hard onto the cement. Pinocchio repeats this until the coconut cracks. This invention seems to be unique, since no other monkey on the island uses the trick. The complexity of it makes it unlikely that other monkeys will imitate it. Pinocchio is therefore the only rhesus monkey that has coconut on the menu.
According to the researchers the trick is specific and functional. This may explain why the other monkeys have not yet succeeded in imitating it. This suggests that certain behaviours can only be transferred under very specific circumstances. The researchers do not know yet what these circumstances are.

The rhesus monkey in the picture is not Pinocchio.