Much analysis of the human brain focuses on the neo-cortex, emphasizing human intelligence. Such is an appropriate topic because humans do have very large brains, relative to their body size. Still, this emphasis and indeed the celebration of human intelligence often under-emphasize the sub-cortex where emotions in mammals are activated. In this paper, the goal is argue that emotions were the driving force behind brain evolution over the last 6 million years. Without growth in sub-cortical areas of the brain, growth in the neo-cortex could not have occurred since all cognitions must have emotional tags to be remembered and used in thinking and decision-making. Moreover, since articulated speech and the emergence of symbolic culture depend upon enlarging the neo-cortex and other body systems, the evolution of emotions and the structure of the sub-cortex is not only critical to growth of the neo-cortex but also the capacities of humans for speech production and codification of symbolic culture. From the perspective of neuro-sociology, then, the evolution of human patterns of social organization—driven and held together by emotions—is a much better starting point in explaining how and why the hominin and eventually human brain began to grow. Such an arguments represents a quiet critique much analysis in psychology and biology. Indeed, without a sociological perspective to explain the evolution of the sub-cortex in the hominin brain, explanations of the neo-cortex, speech production, and symbolic culture are often incomplete, often relying upon “just so” stories and other more speculative endeavors. Indeed, neuro-sociology is at the center of explanations of how and why the hominin brain grew to human proportions.