In the past two weeks, most people in the world have watched with stunned Olympic gymnasts turning over, jumping and jumping for gold medals. Under the shining of the spotlight, as these athletes perform superhuman skills that ordinary people will never understand, life-long practice and physical mastery have achieved results.
But outside the venues of the 2020 Tokyo Olympics, different acrobatic performances are being staged every day. Whether it is close to the Olympic Games, in the forests of Japan, or on treetops around the world, squirrels will jump several meters in the air, from branch to branch. In this natural arena, the stakes are different: squirrels run around looking for food while trying to escape occasional aerial predators such as eagles. But Robert Full, a biomechanics researcher at the University of California, Berkeley, said the speed and ease with which they navigate the challenging and unpredictable canopy environment is “astonishing.” These animals land easily, and the length of their jumps is several times the length of their bodies. Full said, we really don’t know how they did it. “How do they know that their bodies are capable of making these jumps?” he asked.
Full explained that the coordination between the body and mind of the squirrel is not just the curiosity of the human observer. Performing well-performed movements may influence the design of more intelligent robots, incorporating some of the best physical characteristics of squirrels: flexible spine, gripping claws, and gripping claws. Squirrels are not just brave acrobats; they are also skilled learners. “They have a very good memory,” said Gregory Byrnes, who studies biomechanics at Siena College in Loudonville, New York. The squirrel you see jumping in the park is very good. It may have followed the same path before and drew a road map in the brain, Burns said. When the weather gets cold in winter, industrious rodents will recall and retrieve many of the nuts they hid in their territory. Nathaniel Hunt, who studies biomechanics at the University of Nebraska Omaha, says that it is this squirrel that distinguishes them from other arboreal animals, such as some primates. He said that by combining this learning ability with a responsive and flexible body, you will have the temperament of an extraordinary robot.
Hunter and his colleagues wanted to evaluate three aspects of squirrel skills: their decision-making, learning, and innovation abilities. In order to capture the ability of free-range animals, the researchers decided to test these qualities of wild fox squirrels in an outdoor environment in the woods near the University of California, Berkeley. First, they must let wild squirrels really participate in the experiment-for such a cunning animal, this is not an easy task. “Some squirrels get distracted and decide,’It’s time to take a nap,'” Hunter said. Fortunately, most subjects understood what to do after trying a few times and getting some reward peanuts. Any gardener with a bird feeder will tell you, “They are very food-conscious,” Hunter said.
The researchers let squirrels walk through an outdoor obstacle course and track their jumps with high-speed video. In one task, they coaxed subjects into jumping over gaps of different distances from tree-like poles like diving boards. The ledge bends easily under the weight of a squirrel, depending on the distance of the animal from the “trunk”. This situation forces them to make a decision: should they jump from the end of the branch to shorten the distance, but risk an unstable bend when the branch meets the requirements? Or should they be close to the “trunk” during launch, but risk jumping further?Squirrel is Sensitivity to the bending of branches is 6 times the jump distance, The researchers report in a paper published today science. “They are more affected by the amount of bending of the branches than by the distance they must span,” Hunter said of the squirrel.
Hunter speculated that there may be an element of self-confidence at work in their tiny brains: squirrels’ ability to jump on themselves is more certain than that the curved branches below them will not break and fall. When scientists change the flexibility of branches or jump distances, squirrels quickly adjust their techniques to adapt to the changes, learning to change their firing speed in a few attempts.
But when the team leaned the “branch” against the vertical wall to further extend the jumping distance, the real fun began. Surprisingly, the squirrel did not just jump between the ledges, but jumped and pushed away from the wall in a series of parkour-like movements. The researchers quantified and classified these movements. Hunter said the squirrel used a wall to create an additional point of contact for air adjustments, either pushing itself further forward, or braking when leaving a vertical surface to slow it down. “What really surprised me was the extent to which they would use any type of structure they could reach,” he said. Full explained that scientists did not expect that squirrels would use walls to their advantage or improve their parkour skills in subsequent paths. “Their innovation is right before our eyes!” he said. Not a single squirrel fell in any test. Some do not land on the target surface with perfect skill: for example, they may swing below the platform or tilt above the platform. But the animals land every time.
“It’s really cool,” said Burns, who was not involved in the study. “This is a good quantification of these things that animals do, but we don’t know how to describe them.” Byrnes said that he would like to understand the deeper mechanism of jumping, to see what the limbs are doing, and the different types of squirrels. How much energy is lost in the jump. The work of the Hunt and Full teams is part of a larger, multi-agency collaboration to study and apply the principles of squirrel movement. In addition to creating robots that can perform similar actions, researchers are also studying what happens to the squirrel’s brain during these momentary jumps, and how these jumping behaviors develop over time as the little squirrels grow up. Full said that although these animals are everywhere, we are just beginning to understand and appreciate how they run on the treetops. “They made great choices and they were very creative,” he added. “They are extraordinary.”