Over the Memorial Day weekend, a 4-year-old boy climbed the guardrail at the Cincinnati Zoo and into the enclosure of a 17-year-old silverback gorilla named Harambe. By now, most people know how this played out. The boy’s mother had lost track of him, long enough that he crawled over a wall and fell 10 feet into a moat at the bottom. Harambe stood over the child, as if protecting him from the people yelling above, then grabbed the boy’s arm and jerked him through the water. Tranquilizing the gorilla wasn’t an option, the zoo director would later say, because the sedative takes time. And no one could predict how a drugged animal that weighs 450 pounds would react. So they shot Harambe dead.

Zoos have changed a lot in the past 50 years. The openness of Harambe’s enclosure, the cliffs separated by a moat, were designed to lend it a more natural feel for viewers, and to simulate wild environment for the gorillas. It is a departure from the bars and sanitized tile floors of past zoo design. As people become more sensitive to the lives of these animals, they’ve understood how flat concrete and tight confinement can cause depression, even phobia, in everything from donkeys to snow leopards.

Someone at the Cincinnati Zoo caught much of what happened on video (not the shooting), and immediately afterward people blamed both the mother—why wasn’t she watching her son?—and the zoo director—was there no other option?

Few people have asked why a zoo, full of dangerous, or not-so dangerous animals, is even necessary. That might be because calling for an end to zoos has typically been the cause of poets and animal-rights activists. Most past arguments against zoos have focused on the insensitivity toward animals. As Benjamin Wallace-Wells wrote two years ago in a piece for New York magazine titled, “The Case for the End of the Modern Zoo”