The idea of the zoo goes way back: Archaeologists have discovered evidence of a zoo belonging to the pharaohs in ancient Egypt, and Chinese emperors around 1000 B.C. are known to have kept large animals in cages. But it wasn’t until the early 19th century that public zoos began appearing, in European cities like Paris and London. The first American zoo opened in Philadelphia in 1874.
Today, there are more than 200 zoos in the United States. Last May, a 3-year-old boy fell into the gorilla enclosure at the Cincinnati Zoo, prompting authorities to shoot and kill a 17-year-old lowland gorilla named Harambe. The incident shocked Americans and rekindled a long-standing debate about the ethics of zoos and aquariums and keeping animals in captivity.