Spontaneous Altruism by Chimpanzees and Young Children

1. Spontaneous Altruism by Chimpanzeesand Young Children Felix Warneken, Brian Hare, Alicia P. Melis, Daniel Hanus, Michael Tomasello

2. People act on behalf of others • (even unfamiliar) w/o immediate personal gain • Is altruism found in human evolutionary relatives? The chimpanzee? • Studies show altruism to be species specific to humans. • Chimps believed to be solely guided by self-interest

3. However tests did not consider … • consequence of food competition in chimps (chimp too busy trying to get food for itself) • chimps didn’t indicate to subject any need for help

4. First Experimental Evidence for Altruistic Behaviors in Chimps • Human-raised chimps provided unrewarded helping behaviors toward human caregiver

5. Research suggests chimps are able and willing to help, but only in restricted contexts. • Do chimps help only a familiar, nurturing human caregiver where compliant behavior had been reinforced ? - Still unclear if chimps will help other chimps (chimps helping humans ≠ competition) • Do chimps only help others if costs are low (unlike humans)? - Only low cost experiments have been done so far

6. Compare Chimps and Human Infants to assess these issues Exp. 1: Helpfulness of chimps & infants toward unfamiliar individuals Exp. 2: Higher physical effort to help (no rewards) Exp. 3: Novel task to eliminate classical conditioning from past rewards

7. Methods • 36 semi-free ranging chimps • All orphans • Chimps never fed, trained or tested by 1st experimenter • 36 18 month-old babies • Four conditions: Reach–Reward; Reach–No Reward; No Reach–Reward; No Reach–No Reward

9. Experiment 1 • For chimps, value of object was first established • Subjects performed 10 trials for 1 of 4 conditions • Each trial lasted 60 seconds • 1st 30 seconds: E1 focused on object • 2nd 30 seconds: E1 switched focus between object and subject, said subjects name • experiment 1 – chimps , infants

10. Experiment 2 • Retested all chimps and infants that had helped in previous experiment • 18 chimps, 22 infants • Same as experiment 1, except obstacles were added • 2.5m tall raceway for chimps • Objects on the floor for infants • Subjects randomly assigned a condition • Reaching or no reaching

12. Experiment 2 • chimps • Infants

13. Experiment 3 • Tested whether chimp would help another chimp • Recipient chimp was placed in a room with a door • Food was on the other side of the door • Couldn’t be opened by recipient chimp • Door was locked by a chain that was hooked on subject’s cage by a peg • Subject could unhook peg to unlock recipient’s door • Same 3 chimps were always used as recipients

14. Experiment 3 • Control: no food on other side of door • Each subject performed 5 trials for each condition • Subject would not receive food regardless of its actions • experiment 3

15. Main Findings -semi–free ranging chimpanzees helped an unfamiliar human to the same degree as human infants, rewarded or not, at a high cost. -subjects helped unrelated conspecific by using a newly acquired skill on behalf of another individual

16. Results- Experiment 1 • If the chimps have interest in other, they will help the experimenter without a reward

17. Results- Experiment 1 • Helping occurred more often in reaching than non-reaching (p<.001) • In both chimps and human infants • Even independent of reward • Reaching was the only significant factor • Helped experimenter achieve goal without regard to reward • Rewards did not even raise the helping rate

18. Results- Experiment 1 • Species Difference • Human infants helped faster than chimps • During the first 30 sec (when experimenter only cued with gaze) • Chimps needed additional cues

19. Results- Experiment 2 • To replicate the finding that rewards are not necessary- no rewards were offered • Found no difference between conditions in either species • Authors comment: • Help sustained with ↑ cost • Help does not require reward

20. Summary Results- 1 & 2 • Altruistic motivations to help others not unique to humans • chimps act on the behalf of others • even if unfamiliar human and without reward • Could be learned from being rewarded in the past, need novel situation • Do chimps help other chimps?

21. Results- Experiment 3 • Chimpanzees released the chain more often in the experimental than in the control, p<0.025

22. Results- Experiment 3 • Experimental condition • Frequency approaching target door increased • Better able to discriminate if help was needed • Subjects released chain faster than in control condition • Subjects behavior always associated with recipients • More likely to release chain if recipient attentive to target door • Subjects never begged after recipient received food

23. Discussion • Altruistic tendency evolved with common ancestor • Chimps have capacity to use newly acquired skill to help a conspecific • Helping occurs spontaneously and repeatedly • even in a novel situation without reward

24. Future Studies • Do chimpanzees engage in reciprocal altruism? • repay with incurred future cost? • Do they punish non-altruistic individuals? • Are helping behaviors driven by empathy with the emotional states of others?