Security, Group Size, and the Human Brain

If the size of your company grows past 150 people, it's time to get name badges. It's not that larger groups are somehow less secure, it's just that 150 is the cognitive limit to the number of people a human brain can maintain a coherent social relationship with. The whole brain-size comparison might be bunk, and a lot of evolutionary psychologists disagree with it. But certainly security systems become more formalized as groups grow larger and their members are less known to each other.