The word "zoo" was coined in the 1840s by the London Zoo, which first called itself a "zoological garden," but the idea of holding animals in public viewing cells dates back to 3500 B.C. in Egypt. Ancient Rome collected exotic animals, too, although they were often forced to fight each other (or humans).
Zoos remained more like prisons than parks well into the 1900s, with animals still spending most of their lives in small cages. As decades passed and the concept of animal rights gained traction, zoos began building more naturalistic enclosures. Today, most modern zoos strive to offer their residents a humane habitat — most, but not all. A few zoos still seem to rely on a handbook from the 1800s, due to either desperate poverty, indifference or both.
Here are six of the saddest zoos in the world. (Text: Shea Gunther)