Final answer:
The earliest human ancestors were hunter-gatherers, relying on hunting and gathering for sustenance, until the Agricultural Revolution introduced permanent settlements and agriculture.
Step-by-step explanation:
Our earliest human ancestors lived as hunter-gatherers. Small groups of extended families moved from place to place, following the availability of resources. They depended primarily on hunting animals and gathering wild fruits, vegetables, and cereals for sustenance.
When resources in one area were depleted, they would migrate to new grounds. This lifestyle persisted until the advent of the Agricultural Revolution, which began around 12,000 years ago and led to the establishment of permanent settlements, agriculture, and the eventual rise of cities.