Monkey invents new way to break into coconuts

By Matt Walker
Editor, Earth News

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Master nut-breaker in action (video provided courtesy of J Comins, Harvard University)

A rhesus monkey has been observed inventing a new way to open coconuts.

The monkey, known as 'Pinocchio' by the scientists studying him due to his big nose, first rolls a nut down to the docks on the island of Cayo Santiago, which lies to the east of Puerto Rico in the Caribbean Sea.

He then throws the nut up into the air and watches it smash onto concrete.

The technique is so complicated that no other monkey in Pinocchio's troop has yet learned to copy it.

No other monkeys in this population use the same strategy to open coconuts, which are a highly desired resource Primatologist Jordan Comins Harvard University

Details of the monkey's inventiveness are published in the Journal of Ethology by primatologist Jordan Comins from Harvard University in Cambridge, Massachusetts, US.

Together with colleagues, Mr Comins is studying a population of approximately 1000 individual rhesus monkeys (Macaca mulatta) on Cayo Santiago.

Of these monkeys, just one can open the coconuts that are plentiful on the island.

Pinocchio, officially known as monkey 84J, has learnt to select a nut, then carefully uses a horizontal toss to roll the nut down towards the island's docks.

This is a useful technique since it is cumbersome for a rhesus monkey, which generally walks on all four limbs, to carry a coconut in one or both arms.

Pinocchio the coconut-cracking rhesus monkey

The monkey then reaches the cement docks, selectively choosing one of the flattest and hardest surface areas on the island.

He then repeatedly chucks the coconut up into the air, using what the researchers describe as an "underhand throw".

"Rearing back on his hind legs, he springs upward into a small hop while propelling his front arms upward, creating an underhanded throw," explains Mr Comins.

"After 84J releases the coconut from his hands, it travels up several metres in the air before falling on the cement dock or nearby rocky terrain and this process is repeated until the shell cracks, allowing him access to the nutrients inside."

Highly desirable

The invention of Pinocchio appears to be unique.

"What surprises me the most is that, up to this point, no other monkeys in this population use the same strategy to open coconuts, which are a highly desired resource on Cayo," Mr Comins told the BBC.

"So, at the moment, it seems that 84J has a monopoly over the island's coconuts."

His actions may also help scientists understand how new behaviours, or culture, can spread between primates.

SOURCES Visit the Journal of Ethology to read more about the coconut-cracking monkey

Pinocchio's coconut-breaking trick is specific and highly functional, which might explain why other rhesus monkeys have yet to mimic the behaviour.

That suggests certain behaviours can only spread under specific conditions, though Mr Comins suspects it will take a great deal of further research to understand what these might be.