This hypothesis suggests that social manipulation drove the development of the human brain rather than obstacles presented by the environment and organisms other than human beings. This theory explains the intelligence of many ape and dolphins.
However, this theory does not fully explain the development of the human brain. That requires Geoff Miller’s Theory on the Development of Intelligence.
“What [Nicholas] Humphrey and [Richard] Alexander described was essentially a Red Queen chess game. The faster mankind ran– the more intelligent he became–the more he stayed in the same place because the people over whom he sought psychological dominion were his own relatives, the descendants of the more intelligent people from previous generations. As Pinker and Bloom put it, ‘Interacting with an organism of approximately equal mental abilities whose motives are at times outright [sic] malevolent makes formidable and ever-escalating demands on cognition. If Tooby and Cosmides are right about mental modules, among the modules that were selected to increase in size by this intellectual chess tournament was the ‘theory of mind’ module, the one that enables us to form an opinion about one another’s thoughts, together with the means to express our own thoughts through the language modules. There is plenty of good evidence for this idea when you look about you. Gossip is one of the most universal of human habits. No conversation between people who know each other well — fellow employees, fellow family members, old friends — ever lingers for long on any topic other than the behavior, ambitions, motives, fralities, and affairs of other absent — or present — members of the group.” (332, The Red Queen)
The Red Queen by Matt Ridley