Squirrels need to learn how to jump from one branch to another. Lessons that robot builders also hope to learn from.
They are popular YouTube videos. Squirrels perform acrobatics among the trees. They jump from branch to branch with obvious ease. True, they never fall. It wouldn’t be good either. If the fall is not fatal, they are easy prey on the ground.
This week there Video Came to me. Not a nature filmed this time, or a pretty video, but a scientific study. Biologists at the University of Berkeley wanted to know how squirrels behave in their strange behaviour. How did they learn that? How do they know the jump will work?
Jumping requires thinking
The study was published Friday in the journal Sciences, is a logical continuation of earlier work by biologists. For decades, they have studied how geckos and crickets as well as squirrels move and how they seem to stick to all kinds of surfaces. But that’s different, they said in an accompanying press release. Jumps require not only physical skills, but also thinking. “They have to do an environmental assessment,” says Robert Foll. “Which branch do I jump from? Can I get that distance? And above all: do I jump or not?”
It’s still a long way off, but understanding the squirrel’s learning process could aid the development of intelligent robots, says Voll: “A robot sent into a collapsed building or a mine in search of survivors can also face challenges. It then has to make a decision. Is Do I jump into this hole, or over this piece of rubble?”
Squirrels are quick learners
For their research, the biologists built a set with a springboard and another little “branch” on which a delicious nut was waiting. The biologists were able to vary the jump distance, as well as how stiff the board is. This gave squirrels a problem that they also encounter in nature. Do they run all the way to the end of the branch for the jump? Then the distance is short, but the branch is so wobbly that it hardly provides any outlets. Near the trunk, the squirrel knows how to turn the jump, but the distance is great.
It turns out that animals are quick learners. After about five attempts, they knew exactly how to jump on each plank. And in the process of learning, board stiffness proved to be six times more important than distance: squirrels prefer a certain long jump rather than a wobbly one.
Masters in correcting themselves
That far jump didn’t have to be a certainty. Squirrels have proven themselves to be masters of self-correction. They made up for a small deflection by swinging the stick up or down like a gymnast. At very great distances, they had another trick up their sleeve. They then briefly push themselves against the setup’s vertical side wall to be able to adjust their direction and descent speed while jumping.
These are skills that robotic biologists can only dream of at the moment. Because they acknowledge in their press release that the squirrel is unparalleled in the biological game between balance and flexibility.
