An Integrative Hypothesis of Brain Evolution.

The purpose of this article is to reconcile the hypotheses that: (1) brain evolution occurred due to a change in diet, and (2) it occurred due to pressures related to understanding more and more about the underlying causes, such as understanding increasingly complex manipulative and cooperative intentions on the part of the other, as well as understanding reality itself (and how to interact with it beyond group issues). I argue that the ingestion of fat, a highly energy-efficient food, would have unlocked the evolutionary process that culminated in the emergence of the practice of reasoning about underlying causes; and that the consolidation of such a practice resulted in a continuous pressure to increase cognition about "whys"; so that many explanations ended up imposing the need for additional ones, and with that came a high level of awareness and the need for the brain to evolve not only in terms of providing a higher level of cognition but also in size.