As a reward for all their valuable time and knowledge, they offer them symbolic status: they lavish them with eye contact and defer to them in conversation; they might maintain a hunched, subservient posture; bare their teeth in submissive displays known as ‘fear grimaces’ in apes and ‘smiles’ in humans; fetch them food, drink or other gifts; walk behind them; hold doors open; seat them in a special location or use honorific titles to address them.
