We were hunters-gatherers. • We lived in tribes led by chieftains. • We were nomads. • In order to find calories, we had to spend the same amount of calories. • Everybody was mostly engaged in finding food. This left very little time to do anything else. • The society was very egalitarian. • Famines were regular. Before Agricultural Revolution
• It took thousands of years to spread across the World. • It occurred near rivers and isolatedly. • Main energy sources: labour, animals, direct wind and water. Agricultural Revolution .