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Jensen, Hare, Call & Tomasello (2006): What’s in it for me? Self-regard precludes altruism and spite in chimpanzees . from Jensen et al 2006a. B. A. Personally disadvantageous behavior = altruism or spite
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Jensen, Hare, Call & Tomasello (2006): What’s in it for me? Self-regard precludes altruism and spite in chimpanzees
from Jensen et al 2006a B A • Personally disadvantageous behavior = altruism or spite • Altruistic Punishment = spiteful behavior by A in response to previous selfish behavior by B • Disadvantageous inequity = other’s gains greater than yours • Advantageous inequity = other’s gains less than yours
Experiment 1. Mutualism & selfishness: Do chimps prefer selfish or mutualist feeding strategies? Actor can reach only inner cup of either table Recipient can reach outer cup of accessible table if actor chooses this table
Experiment 1: Results • Data collapsed – no session, recipient, or testing order effects • Recipient’s presence or absence did not influence actors’ choices. • Not selfish • Not adverse to disadvantageous inequity Data collapsed – no session, recipient, or testing order effects Recipient’s presence or absence did not influence actors’ choices. Pull choices Grey = accessible table Black = inaccessible table
Experiment 2. Altruism & weak spite:Will chimpanzees choose altruism (no reward) or withholding (no bananas to either)? Bananas only in outer cups so pull →no bananas for actor/recipient or banana for recipient only
Experiment 2: Results No difference between test and control conditions Neither altruistic nor spiteful Not other-regarding or averse to disadvantageous inequity Data collapsed (no order or recipient effects) Kin made fewer choices. Altruistic and spiteful choices not affected. Pull choices Grey = accessible table Black = inaccessible table White = no choice
Experiment 3.Altruism & spite:Will chimpanzees actively prevent recipients from getting banana treats? If actor does nothing* (15-25s) → recipient gets banana If actor pulls inaccessible table → no bananas for either *If actor does not pull inaccessible table rope,within 10 sec E moves accessible table torecipient. During move,actor able to pullinaccessible table,preventing recipient’s banana acquisition.
Experiment 3: Results No difference between control and test conditions Lack of other-regard or tolerance of disadvantageous inequity aversion? Data again collapsed Kinship (with alpha male) does not affect “doing nothing” or pulling away from or towards recipient. Pull choices Grey = accessible table Black = inaccessible table White = no choice
Summary: Chimps indifferent to payoffs for conspecifics No difference mutualism & selfishness No difference altruism & weak spite No difference altruism & spite Pull choices Grey = accessible table Black = inaccessible table White = no choice
Discussion • Chimps not other-regarding • Indifferent to inequity in food-acquisition context • No evidence of anger (as occurs in humans) • Chimps focus on self • Differ from humans • Features of cooperation arose within last 6 million years of human evolution