6. Leaders gain trust by conforming

A high-profile, high-status role in any group is that of its leader, but where do leaders come from? In some groups, they are appointed or imposed from outside, but in many groups leaders emerge slowly and subtly from the ranks.

7. Groups can improve performance...

8. ...but people will loaf

9. The grapevine is 80% accurate

Intelligence, rumour, gossip and tittle-tattle is the lifeblood of many groups.

10. Groups breed competition

While co-operation within group members is generally not so much of a problem, co-operation between groups can be hellish. People may be individually co-operative, but once put in a 'them-and-us' situation, rapidly become remarkably adversarial.