Ninety-nine Percent Of The Time Humans Have Lived On This Planet We've Lived In Tribes, Groups Of 12 To 36 People. Only During Times Of War, Or What We Have Now, Which Is The Psychological Equivalent Of War, Does The Nuclear Family Prevail, Because It's The Most Mobile Unit That Can Ensure The Survival Of The Species. But For The Full Flowering Of The Human Spirit We Need Groups, Tribes.