Primates have ‘hard wired’ warning calls for different predators

Monkeys share a universal language of ‘hard-wired’ warning calls to protect themselves from a range of predators, study claims

  • West African green monkeys have two warning calls, for snakes and leopards
  • Each call triggers a different behaviour which allows them to avoid being eaten  
  • Monkeys now also devised a third call for drones despite not seeing them before
  • The sound they came up with is extremely similar for the one used by a different species for when an eagle is nearby 

Monkeys are thought to have language ‘hard-wired’ in their brains after creating a warning call for man-made drones.

In the natural world, West African green monkeys have two warning calls, for snakes and leopards.

When they hear the snake warning call, they stand very still on two legs to avoid getting bitten, while the leopard warning call makes them climb a tree so they can’t get caught.

However the monkeys have spontaneously come up with a third call, for drones, despite never seeing them before.

 

In the natural world, West African green monkeys (pictured) have two warning calls, for snakes and leopards. Devised a third call when drones nearby which is extremely similar for the one used by a different species for when an eagle is around 

Green monkeys do not have a call to warn about aerial predators because birds of prey are not thought to attack them.

But the call they devised for drones is startlingly similar to the warning sound used by vervet monkeys, when they are under threat of attack by eagles.

Scientists say this shows primitive language is ‘hard-wired’ in monkey brains, available to be used just as soon as they need it.

Professor Julia Fischer, senior author of the study from the German Primate Centre, said: ‘The animals quickly learned what the previously unknown sounds mean and remembered this information. 

‘This shows their ability for auditory learning.’ Researchers flew drones towards West African green monkeys living in Senegal, at a height of 60 metres, or almost 200 feet.

As the drones circled above them, the animals produced chirping warning sounds, scanning the sky and running for cover just as vervet monkeys do when eagles are overhead.

Green monkeys do not have a call to warn about aerial predators because birds of prey are not thought to attack them. But the call they devised for drones is startlingly similar to the warning sound used by vervet monkeys (pictured), when they are under threat of attack by eagles

Green monkeys do not have a call to warn about aerial predators because birds of prey are not thought to attack them. But the call they devised for drones is startlingly similar to the warning sound used by vervet monkeys (pictured), when they are under threat of attack by eagles

Incredibly, after hearing a drone in the sky only one to three times, the monkeys remembered the threat almost three weeks later.

When researchers played five green monkeys the whirring sound of a drone, 19 days later on average, four looked up at the sky to try to find the drone. Three out of the five ran away in fear.

HOW DO PRIMATES COMMUNICATE ABOUT PREDATORS?  

In the natural world, West African green monkeys have two warning calls, for snakes and leopards.

When they hear the snake warning call, they stand very still on two legs to avoid getting bitten, while the leopard warning call makes them climb a tree so they can’t get caught.

However the monkeys have spontaneously come up with a third call, for drones, despite never seeing them before.

It is thought all monkeys, regardless of species, have the same warning calls. 

This means that despite never seeing a threat before they use the same warnings as other animals if they come across them in the wild.    

The same result was not seen for similar sounds played to the monkeys, including buzzing bees, high-pitched cicadas and generators.

This may explain why monkeys kept in isolation, who do not grow up with others of their kind, can still produce the typical sounds of their species.

Monkeys, as seen with drones, have an inbuilt ability to produce sounds they have never hear before in situations where it is needed.

The study, published in the journal Nature Ecology & Evolution, compared the warning calls of West African green monkeys with those of East African vervet monkeys, usually found in Kenya, Botswana and South Africa.

Researchers found the drone alarm calls could be easily recognised, sounding entirely different to the sounds the green monkeys made when faced with ground-based predators like leopards and lions, or pythons and other venomous snakes.

The ‘aerial predator’ call was correctly identified by scientists up to 95 per cent of the time.

The study concludes: ‘In response to the drone, the animals produced clearly discernible calls and a number of subjects ran for cover.

‘Furthermore, we noticed that the animals rapidly detected the sound of the drone and started to look around even before the drone became visible.’

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