Rafts and boats
From one end of a water body to another, humans of the stone ages would wade through and sometimes sadly get devoured by crocodiles and other predators. Ancient Africans then studied the movement of wood planks as they floated on water bodies and realized how some animals move by hanging on to these wood planks. They devised this method and soon constructed rafts which were a combination of multiple planks. With time they fashioned boats and used them to transport their items.
