ABSTRACT
This chapter focuses on the pre-adaptations that hominins inherited from their great ape ancestors and how Darwinian natural selection rewired the hominin brain to take advantage of these pre-adaptations to make hominins more social and more group oriented. The hominin descendants of arboreal apes would thus increasingly be forced to overcome their behavioral propensities for weak social ties and unstable group formations, or die. The timing of the gradual movement of hominins to more open landscapes fits nicely with evidence that, about 2.5 million years ago, a new cycle of lower temperatures with advancing glaciers began. As the subcortex grew during hominin evolution and thereby increased the capacity of hominins to experience and express a larger palette of emotions, this expanded emotionality would also allow for growth in the size of the neocortex from late Homo habilis through Homo erectus to Homo sapiens. Virtually all mammals possess at least four primary emotions of assertion-anger, aversion-fear, disappointment-sadness, and most importantly, satisfaction-happiness.
