I have long maintained that the Dunbar Number a we supposedly can only maintain a small number of close relationships, and only remain connected to 150 people in total a isn't a constant: it's a variable. I have been on the look out for research that supports this premise, and something new has come to light. ALisa Feldman Barrett, working with a team at Mass General Hospital in Boston, has new research that suggests that the size of the amygdala correlates strongly with the number of close friendships that people maintain.