In the Paleolithic era that preceded the Neolithic era and revolution, farming and domestication of animals were virtually nonexistent. To obtain food, families had to relocate as the herds of wild animals migrated; they also were forced to relocate when the vegetal supply was depleted in their area. The vast majority of the population consisted of hunters and gathers, so the tools of that time period were used for hunting and gathering purposes. These tools were simple stone tools made by chipping away at one stone with another stone. Although writing with an alphabet system had not entered society, there is evidence of Paleolithic artwork such as carvings of women and animals and cave drawings. The purpose of these artifacts is unknown, however many scholars believe the figures of women could represent early worship of a fertility goddess; It is also accepted by some scholars that the artifacts held no religious value but were early attempts to display the world around them in an artistic way. As human intellect evolved, numerous changes occurred. Those changes led to the Neolithic Revolution. Many researchers question the exact cause of the Neolithic Revolution. However, it is generally accepted that there was not one singular cause of the Neolithic Revolution. Most scientists agree several factors played a role in the advancement of civilization during the Neolithic Revolution. One theorized aspect is a biological evolution of the human brain. This biological