Charles Darwin’s The Variation of Animals and Plants under Domestication was published in 1868, nine years after On the Origin of Species. Among a number of topics related to domestication and heredity, the book asked why tamed animals tend to have floppier ears, shorter snouts and lighter, blotchier skin than their wild counterparts – a set of traits he referred to as ‘domestication syndrome’. The question went unanswered during Darwin’s lifetime but, as this animation from NPR’s Skunk Bear reveals, scientists might have recently discovered the answer hiding in the cellular makeup of domesticated animal embryos.