The author criticizes zoos for keeping animals in enclosures that deprive them of freedom and natural selection. They argue that the justifications used for zoos, like providing food and shelter, wouldn’t be acceptable if applied to humans. The author compares zoo enclosures to a form of enslavement and highlights the negative impact captivity has on animal behavior and mental health, including the development of stereotypical behaviours. They advocate for animal sanctuaries as a more ethical alternative.