I've always thought that agriculture brought about the first harnessed source of energy--raiding your neighbor to capture slaves to work the fields.
And isn't it interesting that slavery ended when fossil fuels were discovered...
I don't believe that either. (The evidence for earlier civilizations are underwater.)
Guess again there is still a great deal of slavery in world. In the birth place of civilization and humanity no less. Slavery is rampant in North Africa and the Middle East.