Humans are much more complex in the way they interact socially, so they need a greater ability – or a better ability – to pick up on those subtle cues and use that information to guide their future decisions than a macaque would," Patel says. It's therefore possible that this additional network is used to detect behavioural information that macaques don't need. The study didn't look at social behaviours, however, so that idea is just speculation for now.