The killing of a young giraffe at a Danish zoo – after which it was publicly butchered and fed to a lion – breaks what should be the most inviolate if unwritten contract when humans remove wild animals from their natural habitat: to protect and keep healthy those animals and their descendants.

A spokesman for the Copenhagen Zoo said the killing with a bolt gun of the 2-year-old giraffe was done to prevent inbreeding of the zoo’s population. The zoo brushed off other options, such as giving the animal to another willing zoo (and there were several) or keeping it in a separate enclosure so that it would not breed. The zoo said it needed that space for more genetically useful animals. The action, and the explanation, cast a harsh spotlight on the role of zoos, a role that is increasingly being questioned as we learn more about wild animals and their difficulties in captivity. Humans love zoos, and have for thousands of years. But in recent years it has become clear that neither entertainment nor even education are enough; humans have weighty responsibilities that go with removing animals from the wild and putting them on display.