Answer :

Originally humans simply hunted and gathered, but this nomadic lifestyle made having a large family difficult and culture was therefore rarely passed on.

During the Paleolithic Age, the principal way to collect food was by hunting animals. Besides, in some population centers of this age, it was common to try to look for vegetation in the wilderness near to their homes, in order to get some type of herbs that could be used as food. However, sometimes it turned out that the herbs or the vegetation were dangerous, and therfeore, in some ocassions, it was damageful to people. That was one of the main problems that the method had.