During the Paleolithic Era humans grouped together in small bands. They lived by gathering plants and hunting wild animals. This way of living is called a "hunter-gatherer society". People hunted small burrowing animals like rabbits, as well as birds and herds of animals like deer and cattle. They also gathered plants to eat, including grains. Grain often grows on grasslands where herds of grass-eating animals are found. People also gathered root vegetables, green vegetables, beans, fruit, seeds, berries, nuts, eggs, insects and small reptiles.