MONKEYS and apes that most often deceive their peers also have the biggest brains relative to their body size. The finding backs the “Machiavellian intelligence” theory, which suggests that the evolution of large primate brains was driven by the benefits of complex social skills.
Of all terrestrial mammals, primates have by far the largest brains relative to their body size, with humans having the largest of all. The enlargement is almost exclusively in the neocortex, which in humans makes up more than 80 per cent of brain mass.
Psychologists Richard Byrne and Nadia Corp at St Andrews University in the…
