The bigger your amygdala is, the bigger your social network. This new research follows up on previous studies that had demonstrated a similar link between amygdala size and social complexity in primates. It's a simple but powerful link: the more people you regularly interact with, the bigger your amygdala. ... What this really speaks to is the so-called "social brain hypothesis", which theorizes that our amygdalas evolved in part to deal with the complexities of human social life. This is more compelling evidence that fundamentally we are meant to be social animals.