It’s well established that when cats fall, they’re able to land perfectly most of the time, nimbly maneuvering to right themselves before they hit the ground. Now, researchers at Japan’s Yamaguchi University have advanced our understanding of this extraordinary ability, focusing on the mechanical properties of feline spines.
What they found, as detailed in a recent study in the journal The Anatomical Record, is that those sure-footed landings are due in part to the fact that a cat’s thoracic region is much more flexible than its lumbar region.
While a cat’s ability to rotate in the air without something to push again seems to defy the laws of physics, it’s instead a complex righting maneuver. To find out how they do it, researchers in the new study first analyzed the spines of five deceased cats, separating the thoracic and lumbar regions and then subjecting them to mechanical tests to measure their flexibility, strength, and resistance to rotation. In another experiment, researchers used high-speed cameras to film two cats dropping onto a soft cushion.
From the subsequent analyses, as told by the journal Phys.org, the team observed that what makes cats masters of falling is their spines, which are not uniformly flexible. In particular, the thoracic region is very flexible: It can rotate about 50 degrees with very little effort. The lumbar region, by contrast, is much stiffer and acts as a stabilizer.
When straightening in the air, therefore, cats first rotate their head and front legs toward the ground because the thoracic spine is flexible, then the entire back of the body follows. The stiffer lumbar region functions as a kind of anchor, allowing felines to rotate the front without losing control.
The results of the new study suggest that the complex midair righting maneuver performed by cats occurs according to a precise sequence. “During air-righting, anterior trunk rotation was completed earlier than posterior trunk rotation,” the study reads. “These results suggest that trunk rotation during air-righting in cats occurs sequentially, with the anterior trunk rotating first followed by the posterior trunk, and that their flexible thoracic spine and rigid lumbar spine in axial torsion are suited for this behavior.”
In addition to unlocking the secret of cats’ ability to fall “upright,” the authors conclude, the findings could help veterinarians treat spinal injuries and even lead to the development of more agile robots.
This story originally appeared in WIRED Italia and has been translated from Italian.