The Critical Role of Dopamine in the Evolution of Human Intelligence and Thermal Tolerance

Modern humans are unique among anthropoids in many key features, including our advanced intelligence, large brain-body size, thermal tolerance, and endurance capability. The objective of this theoretical review is to update the theory of Previc (1999) postulating the importance of dopamine in human evolution by synthesizing newer findings concerning dopamine’s role in human intellectual and endurance capabilities. Recent evidence further supports the putative role of dopamine in advanced human intelligence (especially cognitive flexibility) and thermal tolerance and endurance. One key breakthrough is a collection of recent studies demonstrating a uniquely human dopaminergic innervation of the striatum and prefrontal cortex—both essential to human cognition. Another potentially important finding is the human-specific mutation of an enhancer to the EN1 gene that controls eccrine gland formation and plays a major role in the development of dopaminergic brain systems. A plausible evolutionary scenario is put forth in which the enhanced thermal capabilities linked to dopaminergic evolution may have gradually led to the enhanced intellects of modern humans.