Since the animals in zoos that are kept in captivity are kept away from other animals that could attack and prey on the animals like they would in the wild the animals kept in the zoo live longer than those same animals that live out in the wild.
When in the wild the animals are preyed upon for food by other animals so other animals can and will naturally kill those animals for food.
Also the animals in the wild have to search for and hunt for their food and if they do not get enough food they also die.
Or the animals in the wild could contract diseases from eating stuff in the wild which could kill those animals.
But animals still deserve to have freedom and should not be kept in zoos for our amusement.
Zoos usually take good care of the animals but the animals deserve to be out in the wild and not kept in a cage.