In a Japan lab, degus use an implement to get at food, opening up the possibility that low-intelligence animals may also possess tool-use abilities
Degus are highly social, intelligent rodents native to the highlands of Chile. They adorn the openings of their burrows with piles of sticks and stones, have bubbly personalities and like to play games. But in a laboratory setting, degus can do much more than play hide-and-seek, according to a study in the online journal Plos One. They can learn to use tools.
Specifically, degus have been trained to reach through a fence, grab hold of a tiny rake and pull their favorite food, half a peeled sunflower seed, close enough to reach with their mouths. After two months of practice, the degus can move the rake as smoothly and efficiently as croupiers in Las Vegas casinos.
This is first time rodents have been trained to wield tools, said Atshushi Iriki, a neuroscientist, who led the experiments at the Laboratory for Symbolic Cognitive Development at the Riken Institute in Tokyo. But other species may soon join them.
While it has long been thought that tool use is a hallmark of higher intelligence, Dr. Iriki said, the brain structures that underlie such abilities may lie dormant in many animals with good hand-and-eye or paw-and-eye coordination. Training them to use tools in captivity provides insights into the plasticity of their brains, he said, and may shed light on how early humans evolved tool use in the first place.
“There’s an interesting push-pull to this demonstration of the use of an artificial rake by a rodent,” said Richard Morris, a neuroscientist and expert on animal behavior at the University of Edinburgh, who was not involved in the study. “The push is that if rodents no less than primates can learn to use tools, interesting questions arise about the nature and components of intelligence. And the pull part is that the observation sets the stage for a new neurobiological approach to this fundamental facet of mind, of brain.”
In the wild many animals use simple tools. Chimpanzees and crows actually create them. But an underlying question is, What changes take place in an animal brain when tool use evolves?
To find out, Dr. Iriki initially conducted experiments with Japanese macaques, monkeys that do not tend to use tools in the wild. In the laboratory, he trained them to use a rake to reach out and retrieve their favorite treat, raisins. Later the animals learned to use a short rake to pull in a longer rake, which could then be used to fetch more distant raisins.
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