I guess I'm a little late to the party, but in any case, for the last few days, I've been enjoying this deeply considered multi-disciplinary paper from 2010 by Stanley Ambrose.
Coevolution of Composite-Tool Technology, Constructive Memory, and Language
Implications for the Evolution of Modern Human Behavior
Volume 51, Supplement 1, June 2010
(Link) open access
Abstract: The evolution of modern human behavior was undoubtedly accompanied by neurological changes that enhanced capacities for innovation in technology, language, and social organization associated with working memory. Constructive memory integrates components of working memory in the medial prefrontal cortex to imagine alternative futures. Enhanced mental time travel permits long range strategic planning. Within this broadly conceived area of cognitive neuropsychology, I will focus on two stages of the evolution of cognitive faculties for planning. The first involves executing complex sequences of actions involving manufacture of multicomponent artifacts; the second involves enhanced planning through information sharing, which required the establishment of extended regional social interaction networks based on trust and cooperation. Both stages were probably accompanied by important innovations in grammatical speech.