A fiber inspired by polar bears traps heat as well as down feathers do
The fiber’s porous core and waterproof sheath prevent heat loss
![polar bear](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2024/01/010324_jc_polar_bear_sweater_feat.jpg?fit=1030%2C580&ssl=1)
Polar bear fur inspired the creation of a new knittable heat-trapping fiber.
Patrick J. Endres/Corbis Documentary/Getty Images