“Mastering Nut Cracking: Monkeys Demonstrate the Perfect Shell Opening Technique”

There is no nut too tough for the wild bearded capuchin monkey.

Scientists have discovered that these primates are more skillful in cracking open their favourite treats than first believed.

The monkeys are known to use stone ‘hammers’ to crack nuts, and a new study has revealed how they expertly adjust their force with each strike.

‘Until now, this level of dexterity was not suspected of any monkey,’ said Madhur Mangalam of the University of Georgia.

The researchers filmed 14 capuchin monkeys cracking nuts in Brazil and analysed the footage to find out the height and speed of each strike.

Cracking nuts can be tricky because they have a softer outer husk and a much harder shell inside.

This means they have to approach the nut as a two-stage problem.

They first hit it with a certain degree of force to breach the outer, green husk. Once this has been done, they can hit the inner shell much harder.

‘It was a ‘eureka’ moment when we realised that the monkeys modulated the strikes systematically according to the condition of the nut following the preceding strike,’ Mangalam says.

It never crossed their minds that the monkeys might show such a sophisticated ability to match their action to the physical state of the nut. But that’s exactly what they did.

‘Our finding opens our eyes to the fact that non-human primates modulate their actions with a tool to accommodate the rapidly changing requirements of the task, which is a cognitive accomplishment,’ Mangalam says.

The researchers now plan to examine whether other species make adjustments in tool use in this way.

They will also explore how this kind of dexterity influences each species’ tool-use repertoire.