By Victoria Gill Science reporter, BBC Nature
Chimp (c) Catherine Hobaiter
The chimps made soft “hoo” sounds to warn individuals that had not seen the threat.
Chimpanzees appear to consider who they are “talking to” before they call out.
Researchers found that wild chimps that spotted a poisonous snake were more likely to make their “alert call” in the presence of a chimp that had not seen the threat.
This indicates that the animals “understand the mindset” of others.
The insight into the primates’ remarkable intelligence will be published in the journal Current Biology.
The University of St Andrews scientists, who carried out the work, study primate communication to uncover some of the origins of human language.
To find out how the animals “talked to each other” about potential threats, they placed plastic snakes – models of rhino and gaboon vipers – into the paths of wild chimpanzees and monitored the primates’ reactions.
“These snake species are well camouflaged and they have a deadly bite,” explained Dr Catherine Crockford from University of St Andrews, who led the research.
“They also tend to sit in one place for weeks. So if a chimp discovers a snake, it makes sense for that animal to let everyone else know where it
is.”
The scientists put the snake on a path that the chimps were using regularly, secreting the plastic models in the leaves.
“When the chimps saw the model, they would be quite close to it and would leap away, but they wouldn’t call,” she told BBC Nature.
“It wasn’t a knee-jerk reaction.”
After leaping away, each chimp immediately, very carefully, approached the snake again. And this time, they would make a soft “hoo” sound if they were close to a chimp that was not aware the snake was there.
“We monitored the snake all day, so we knew which animals had seen it and which hadn’t,” Dr Crockford explained.
She added that when the primates called out, They were “very focused on their audience.”
“That’s not entirely new,” she said.
“Lots of animals give alarm calls and are more likely to give an alarm call when another animal is present.”
But what is new here, she continued, is that “they seem tuned, not into who the audience is, but to what the audience knows”.
These findings, Dr Crockford said, provide an important insight into a factor that may have “kick-started” complex communication.
Read more at: BBC Nature