Don animals live longer in zoos than they would in the wild?
In some cases, this is true. But it is irrelevant. Suppose a zoo decides to exhibit human beings. They snatch a peasant from a less-developed country and put her on display. Due to the regular feedings and health care that the zoo provides, the peasant will live longer in captivity. Is this practice acceptable? A tradeoff of quantity of life versus quality of life is not always decided in favor of quantity. –DG Humans and other animals have instincts to be with and to protect their own families, and to have free will. Sometimes we under-estimate the importance of these desires: What All Beings Want.
