A City Guide of Ahiri for Thus the development of social cooperation during childbirth contributed to the evolution of larger brains. Whereas many accounts of the expansion of hominid evolution focus on male activities, such as hunting, group defense, or knowledge of the terrain, a political scientist observes, an explanation based on social cooperation [of women during childbirth emphasizes a factor that otherwise would have limited evolution toward larger brain size. . . . It is often argued that humans cooperate in society because they have big brains. Perhaps the truth is that we have big brains because we cooperate in society. A City Guide of Ahiri 2016.