What I learned reading: Nonzero – Robert Wright

When you look at the mechanism of natural selection there's an argument to make it favours nonzero-sum dynamics (win-win situations) as it aids genetic proliferation. If nonzero-sumness helps genes to proliferate, natural selection favours an increase in nonzero-sumness throughout time.

The ability to process information is crucial in order to facilitate (and increase) nonzero-sumness. The better the information processing the better it can facilitate nonzero dynamics. This leads you to complexity. You need divers interconnected interdependent parts whether within an organism or within a society in order to have information processing and the more you have of this the more you increase complexity.

The argument of the book is that complexity (vis-à-vis information processing) increased throughout history to facilitate nonzero-sumness as this would be beneficial to inclusive fitness. Extrapolating from this argument you could say complex information processing machines like our brains are an (almost) inevitable outcome of natural selection.