As the monkeys developed these skills, their brains showed signs of gene activity in a brain region that integrates vision and touch. The same was likely to be true of the degu, Dr. Iriki said. The rodent has superb paw-and-eye coordination and a pad on its paw that can act like a thumb.
In the experiments, six degus stood behind a fence with gaps wide enough to let their forelegs pass through but not their mouths. A rake-like tool was placed within easy reach. The animals had to grasp the rake and pull seeds in close enough to eat.
As the degus became more adept, the experimenters placed the seeds further away. The animals had to push the rake around the seed, twist it and pull. The degus did not hesitate to use rakes of different sizes, colors and shapes. They were reluctant to use a tool that had no teeth. Studies are under way to see if the degu’s brain reorganized in response to tool use, Dr. Iriki said.
Meanwhile, the researchers have begun a new set of experiments with marmosets, a small primitive primate, to see if their brains show similar molecular and genetic changes with tool use.
-SANDRA BLAKESLEE (New York Times)