Why isn't anything growing? We're gonna run out of food!
The paleolithic age had unstable food supply. After a while of being in the same place, the plants and animals became scarce, and so they had to find a new place to settle.
Eventually, people started finding ways to decrease their dependence on hunting and gathering. Instead they discovered that they could plant seeds and harvest crops.
In addition, early farmers learned how to domesticate animals, they raised them and used them to provide for people's needs. Farmers raised sheep, goats, and cattle for meat. Goats and cattle also provided milk. Mules helped carry heavy loads and pull plows.