Cats are wily little creatures. Their personalities are questionable, their bodies can wriggle into shapes that seem physically impossible. And how the heck do they land on their feet every time they fall?

Scientists have spent a very long time trying to explain that trick. A new paper from researchers at Yamaguchi University in Japan adds a fresh detail. The team found that a cat’s spine isn’t equally flexible from front to back. The thoracic spine, in the front half of the body, twists much more easily, while the lumbar spine in the lower back stays stiffer. That appears to help cats rotate in sequence, with the front half moving first and the rear following after.

That helps further explain an old scientific obsession. Back in 1894, French physiologist Étienne-Jules Marey used early high-speed photography to capture a cat falling and reorienting itself midair. The images became famous because they showed a cat starting its fall without obvious rotation and still managing to land feet-first. That odd little mystery became known as the “falling cat problem,” and later research showed that cats can turn themselves midair by moving different parts of the body separately.

What this newer research adds is the body mechanics. The researchers tested spinal columns from five donated cat cadavers, keeping the ligaments and discs intact, and measured torque, rotation angle, stiffness, and what they call the neutral zone, the range where movement needs very little force. The difference was pretty stark. The thoracic spine had about three times the range of motion of the lumbar spine, and the lumbar region was markedly stiffer. The thoracic sections also had a neutral zone of about 47 degrees, while the lumbar sections had none.

They also filmed two live cats dropped from about one meter onto a soft cushion with a high-speed camera. The footage showed that the cats weren’t twisting as one solid unit. The front half rotated first, then the back half followed milliseconds later. One cat showed a delay of about 94 milliseconds, the other about 72 milliseconds.

The researchers think this front-first, back-second rotation might help with more than falling. Similar spinal flexibility could also help cats with high-speed turning and other agile movements. Which sounds about right, given everything we’ve seen about cats.