LifeBusy doing nothing: How sloths mastered life in the slow laneOnce defamed as slow and stupid, sloths are now recognised as masterworks of evolution – and we could all learn from their energy-saving tricksFeatures
PhysicsA 'magic number' of people walking across a bridge makes it sway We thought walking in lock step made bridges sway, like London’s Millennium Bridge when it opened. But it turns out crowd size matters more than rhythm 51¶¯Âþ