Video shows chimpanzees warn their friends of danger up ahead of them
Knowing what someone else doesn’t know enables you to take advantage of them – or, on the other hand, help them. It’s one of the hallmarks of extra brain power, and it’s one of the key arguments that we use to make the case that a particular animal qualifies to be recognized as a “person” in legal and philosophical terms.
During the past few years we’ve learned lots more about the intelligence and language of other animals. But a new study takes this understanding to new levels.
Researchers from the Max Planck Institute set up a study with wild chimpanzees in Uganda and found that the chimps who saw a snake were more likely to make a warning call when they knew one of the clan was close by but probably couldn’t see the snake.
The team, led by Catherine Crockford of the University of St. Andrews, Scotland, set up a study with wild chimps in Budongo Forest, Uganda. They presented them with models of dangerous venomous snakes, two gaboon vipers and one rhinoceros viper.
“As these highly camouflaged snakes sit in one place for weeks, it pays for the chimp who discovers it to inform other community members about the danger,” Crockford explained. “The advantage of addressing these questions in wild chimpanzees is that they are simply doing what they always do in an ecologically relevant setting.”
Video footage of wild chimps foraging in Uganda’s Budongo forest show apes at the front of their groups jumping with surprise on spotting a model snake lying camouflaged in the undergrowth.
When the chimps regain their composure, they call out to those behind them that a threat lies ahead. The video also shows them making calls less often when other chimps already know of the danger.
The team monitored the behavior of 33 different chimpanzees when they saw the camouflaged model snake. The chimps were more likely to make warning calls when they spotted a venomous snake if others in their troop had not seen the danger, researchers found. As chimps “in the know” arrived at the scene, they passed the warning on to others who lagged behind but were still within earshot.
“The chimps would sometimes jump when they saw the snake, but they didn’t call then,” Dr. Crockford said. “They would only call after going back for a second look. So there’s a dissociation between their emotional reaction and the vocalization. The call is not a knee jerk reaction to the snake, it’s intelligent behavior.”
To be able to see something from the point of view of someone else is a highly advanced cognitive skill. It includes, for example, knowing that they’re not seeing something that you can see … knowing what they’re thinking … knowing what someone else in your group doesn’t know … knowing what they do know … knowing that they don’t know that you know … knowing that they’re not sure whether you know it or not … and lots more versions of all this.
Scientists refer to this ability as having a “theory of mind.” And for a long time it was assumed, rather arrogantly, that we humans were the only species on the planet to have a theory of mind. We’re not. More and more studies are showing that lots of other animals are busy figuring out what each other are thinking. They lie and cheat and take advantage of each other’s ignorance (or help each other out) – just like we do.
Roman Wittig, another member of the team in Africa, emphasized that chimps really seem to take another’s knowledge state into account. “They voluntarily produce a warning call to inform the others of a danger that they [the others] do not know about,” he said. “In contrast, chimpanzees were less likely to inform audience members who already know about the danger.
“It is as if the chimpanzees really understand that they know something the audience does not AND they understand that by producing a specific vocalization they can provide the audience with that information.”
Dr. Lori Marino, science editor for Zoe, views these findings as particularly important for two reasons.
“First, they corroborate evidence from captivity studies under very different circumstances showing that chimpanzees can take the visual perspective of other chimpanzees and humans into account,” she said. “Therefore, we now know that this is a robust capacity because it is found in a range of settings.
“Second, the present study demonstrates that this capacity is present in a real-world situation in the field and therefore has more external validity than the captivity studies.
Being able to communicate missing information may also have been critical to the evolution of language. (Why would you go out of your way to communicate to others in your group unless you know they don’t know what you know?)