How do pets differ from wild ancestors in structure and behavior?

Domesticated animals differ from their wild ancestors, primarily in size, sometimes the ancestors of domesticated animals can be tens of times larger. This is due to the fact that pets did not need to hunt, they received food from humans, which means there is no need for a massive body. Yet domesticated animals retained some of their predatory instincts. Wild ancestors lived in flocks and hunted like that, domestic animals often live alone, so their flock is a human society.