After years of training wealthy boys that learned how to read and write would become?

Scribes

Explanation:

Only a few people—mostly boys from wealthy families— learned how to read and write cuneiform. After years of training, some students became scribes (SKRYBS), or official record keepers. Scribes wrote documents that recorded much of the everyday life in Mesopotamia, including court records, marriage contracts, business dealings, and important events. Some scribes were judges and government officials.

food chain i would say only because there is competition on getting food and survival