1. Is Altruism Really Selfless? “As a general rule, a modern biologist seeing an animal doing something to benefit another assumes either that it is being manipulated by the other individual, or that it is being subtly selfish.” -- George Williams

2. Was Mother Teresa an Altruist? “If the knowledge of torture of others makes you sick, it is a case of sympathy... It can be argued that behavior based on sympathy is in an important sense egoistic, for one is oneself pleased at others’ pleasure and pained at others’ pain, and the pursuit of one’s own utility may thus be helped by sympathetic action.” -- Amartya Sen

3. Backstory Comparative Advantage

4. Comparative Advantage (specialization)

5. Equal Allocation of Resources

6. Mis-Allocation of Resources

7. Efficient Allocation of Resources

8. Reciprocal Altruism = Trade Cooperation is the hallmark of the human species Optimization via Specialization Small differences in capability are amplified and reinforced Increase in efficiency can maximize “utility” given an equitable exchange mechanism If benefits of specialization exceed costs, utility increased individually and collectively

9. Backstory Game Theory

10. Prisoner’s Dilemma (one-shot) CD C -1, -1-10, 0 D 0, -10-3, -3

11. Tit-for-Tat (90%-repeated) CD C -11, -11-40, -30 D -30, -40-33, -33

12. Cooperation Between Sisters (nominal payoffs) CD C 10, 102, 12 D 12, 24, 4

13. Cooperation Between Sisters (50% inclusive fitness) CD C 15, 158, 13 D 13, 86, 6

14. ActionBenefit/Cost Gain resource +20 Lose resource 0 Injury to self -40 Cost of display -4 Hawks vs. Doves (pure strategies)

15. Hawks vs. Doves (payoff matrix) HD H -10, -1020, 0 D 0, 206, 6

16. Bourgeois Strategy (mixed strategy) If you own the resource, fight for it like a Hawk Otherwise, compete for it with displays like a Dove

17. Bourgeois Strategy (payoff matrix) HDB H -10, -1020, 05, -5 D 0, 206, 63, 13 B -5, 513, 310, 10

18. Current Story The Paper

19. “The evolution of cooperation in sizable groups of non-kin in humans has been and continues to be the subject of debate......fundamental questions remain about the number and nature of the cognitive mechanisms that underpin human cooperative psychology and whether there are stable individual differences in these mechanisms.” Premise

20. “Agent-based simulations of the evolutionary dynamics of interacting strategies, which generally embody this assumption, that an agent’s type is stable, causing it to use the same strategy until its simulated death, have helped to inform these issues. Experimental results of the kind reported here can be useful for clarifying whether the assumption of stable types in the realm of human cooperation as assumed by simulations is justified, and, if it is, how best to characterize these types.”

21. “In line with types used in simulations and observed in other experimental contexts, we consider the hypothesis that people are one of three stable types: ” Cooperators: contribute to generating group benefits at a cost to self Free-riders: who do not incur these costs Reciprocators: who respond to others’ behavior by using a conditional strategy

22. Experimental Design 84 subjects, undergraduates 3 groups of 24, one group of 12 Meet in groups of 4, randomly chosen and permuted between rounds Play 7-10 games, time permitting (min 7) First 7 games ‘in-sample’ Extra games ‘out-of-sample,’ used the check error-rate 10 question quiz pre-game (to remove “confusion” confound)

23. Game design Public-Goods game Multi-player (> 2 person) Repeated (why is this important?) Random lengths, 96% chance of repeat Game lengths: 16, 7, 23, 32, 32, 34, 4, 17, 31, 8 Randomization methods not explained to players (grouping or duration) Anonymized via computer terminals

24. Important features! Players can’t predict who they are playing against (why is this important?) Players feel anonymous (why is this important?) Players can’t predict when game will end Players can see what group contributions are (but not individual) Players can change their previous contributions to punish/reward group behavior

25. Game Play 50 tokens per person 4 players Divide tokens between Group and Individual accounts Group account is doubled by experimenter and paid out at end

26. Game Play (cont) Individual contributions equal 1.0 cent to the individual Group contributions equal 0.5 cent to the individual Simultaneous initial contributions, followed by sequential individual turns until game ends Each individual is guaranteed at least one chance to update their previous contribution

27. “This generates a social dilemma, where the group optimum is achieved only when each individual makes a decision that is contrary to her or his income-maximizing self-interest.”

28. Classification Methods Statistical, top-down method Linear Conditional-Contribution Profile (See whiteboard for explanation) Alternative, emergent classifications possible (House, Keane, McCabe, 2004 Econometrica)

29. Linear Conditional-Contribution Profile “The intercept provides a measure of how willing a subject is to cooperate even when his or her group counterparts contribute little to the public good. The slope measures a subject’s responsiveness, both in direction and magnitude, to others’ contributions.” “...the decisions subjects made in games used for classification purposes predict well the decisions they made in games played afterward. Hence, the evidence is that our type classifications are valid, and that our model, although simple, nevertheless provides useful and reliable results.”

30. Findings Stable, polymorphic equilibrium in type distributions 17 Free-riders (20%), 11 Cooperators (63%), 53 Reciprocators (13%), 3 not classifiable (4%) Higher payoffs to groups with higher cooperation score Relatively consistent payoffs between types 70.0 Cooperators to 77.5 Free-riders out of a possible range of values 25 - 125 Average contributions decay over time: from 60% initially down to ~35% at end

31. Polymorphic Distribution