Answer: About the same time they domesticated plants, people in Mesopotamia began to tame animals for meat, milk, and hides. Later, people began domesticating larger animals, such as oxen or horses, for plowing and transportation. These are known as beasts of burden. Domesticating animals can be difficult work.
Before the Roman Republic was transformed into an empire, the nation had a Senate and an executive branch with Consul's acting as leaders of the nation. Rome had an representation in place that was very advanced for an ancient civilization.