Some rodents have a sweet tooth. And sometimes, you need to get crafty to reach your sugar fix.
Rats have been filmed for the first time using hooked tools to get chocolate cereal – a manifestation of their critter intelligence.
Akane Nagano and Kenjiro Aoyama, of Doshisha University in Kyotanabe, Japan, placed eight brown rats in a transparent box and trained them to pull small hooked tools to obtain the cereal that was otherwise beyond their reach.
In one experiment they gave them two similar hooked tools, one of which worked well for the food retrieval task, and the other did not. The rats quickly learned to choose the correct tool for the job, selecting it 95 per cent of the time.
The experiments showed that the rats understood the spatial arrangement between the food and the tool. The team’s study is the first to demonstrate that rats are able to use tools, says Nagano.
The rats did get a little confused in the final experiment. When the team gave them a rake that looked the part but with a bottom was too soft and flimsy to move the cereal, they still tried to use it as much as the working tool that was also available. But, says Nagano, it is possible their eyesight was simply not good enough for them to tell that the flimsy tool wasn’t up to the task.
The rodents’ crafty feat places them in the ever-growing club of known tool-using animals such as chimps, bearded capuchin monkeys, New Caledonian crows, alligators and even some fish.
“I think this is a really important study that urges us to keep open minds about the evolution of tool behaviour,” says Marc Bekoff of the University of Colorado, Boulder. “These tool-using abilities occur in a wider range of species than most people would imagine.”
The results also add to previous research on rats’ cognitive and emotional, capacities, which, as Bekoff points out, people tend to ignore. “We know that rats display empathy, we know that rats like to be tickled and feel joy,” he says. “They are smart and emotional beings.”
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