As we’re a group species, competition between group members is an intense form of selection pressure. Some biologists argue that the relatively rapid development of the prefrontal cortex (which is where much of our illusion of consciousness is created, and where our very rare attempts at reasoning occur) is largely due to this competition. As one person gains advantage by lying, others are exploited. This leads to the emergence of better truth-detection (on average) which in turn spurs the need for more convincing lies. And so the feedback loop results in the development of imagination, that trait in which we seem to excel, compared to other species.

One thing is quite clear, however: despite hundreds of thousands of years of evolutionary pressure we’re still (on average) at quite a primitive stage in our Lie/Detect Lie capabilities. The successes of Brexit, Trump, Modi, Le Pen, Babis, Orban, PiS, Duterte, AfD, et al demonstrate this fact with embarrassing ease.