Long ago, when people were wild animals, they must have been in the same predicament as other animals: carnivores all died of starvation, prey animals all died by being eaten alive.  Pretty grim.  As humans smartened up, they learned to farm, which alleviated the need to hunt and gather, and eventually enabled them to produce more food than they actually needed.  They were better nourished, started living longer, and reproducing more often and more successfully.  The species multiplied.  The ability to grow excess food enabled humans to grow in denser societies, which allowed for greater collaboration, better division of labor, and allowed for spare time to pursue interests other than attaining the next meal.  Thus, knowledge of the world and how to manipulate it grew.