This article examines the possible origins of modern thinking by evaluating the cognitive models of working memory, executive functions and their interrelationship. We propose that a genetic mutation affected neural networks in the prefrontal cortex approximately 60,000 to 130,000 years ago. Our review of cognitive and archaeological evidence yields two possibilities: either it was non-domain specific, affecting general working memory capacity and its executive functions, or the mutation was domain-specific, affecting phonological storage capacity. We discuss the sequelae of these possibilities for modernity, including language enhancement, greater reasoning, planning, and modelling abilities, and increases in fluid/general intelligence.