tl;dr<p>A graduate anthropology student sets out to confirm "humans all share the same cognitive machinery—the same evolved rational and psychological hardwiring."<p>He uses prisoner's dilemma test on an indigenous population near Machu Picchu. His results were vastly different from previous studies.<p>He continued his research across the globe and he finds:<p>- Almost all cognitive research tests is performed on people from Westernised societies. And of all the western societies represented, the overwhelming majority came from America.<p>- Americans are outliers with relation to most cognitive research, even when compared to other western societies.<p>- Our culture directly effects our rational and psychological hardwiring.