Gorillas at a zoo in England have demonstrated a distinctly human trait while attempting to solve a new puzzle game - cheating.
The gorillas were presented with a wall-mounted device where the aim is to guide a peanut through a series of obstacles by poking a stick through various holes to move it along. Eventually the peanut reaches the bottom of the device and drops out.
Some gorillas, however, figured out an easier way to retrieve the nut.
"We've seen a lot of cheating behavior where they've been putting their lips up against the device and sucking the nut out which was not how we intended the device to be used. But it just shows you that they're very flexible, they're capable of creating new solving strategies to access the food," Dr Fay Clark from Bristol Zoo Gardens told Reuters.
"They have some fascinating problem-solving abilities that have probably not been witnessed before," she added.
Since first being introduced to the prototype device earlier this year, the scientists say the game has proved a hit with the troop of endangered western lowland gorillas, who regularly returned to play with the game even when there were no more nuts to win.
The 'Gorilla Game Lab' project from the University of Bristol and Bristol Zoological Society developed the game to encourage the gorillas' cognitive and puzzle-solving abilities. The prototype device had to be strong enough to withstand a frustrated gorilla, which can be seven times stronger than humans. It also had to be engaging enough to keep them coming back for more.
"With each of the modules in the game, they're removable so we can take the modules out, re-designed them and put in an additional module or change the actual structure. So it creates an endless stream of new and novel puzzles for them to solve," said engineer Dr Stuart Gray of the University of Bristol.
While the main aim of the project is to create a "positive psychological state of pleasure and satisfaction in the gorillas", the researchers are already setting their sights on more advanced models that would help zookeepers better understand both the mental and physical condition of the animal.
"Things like eyesight, hearing, other cognitive functions - all of these could be measurable further on down the line," added Gray.