Our noble-savage human nature is like the shocks-and-springs assemblies on modern cars and motorcycles. The springs let the vehicle bounce over rough roads without getting jostled to pieces, while the shock absorbers keep the vehicle from springing out of control. Our savage concoctions of hormones and fists and weapons help us survive the rough rides of Planet Earth (like springs), and our noble side—the finer spirit within—keeps us from churning out of control (like shock absorbers).