Stress reduction through consolation in chimpanzees

1. Stress reduction through consolation in chimpanzees Fraser, O.N., Stahl, D., Aureli, F. Presentation by Adrielle, Minako, Caroline

2. Background on Reconciliation • Reconciliation: postconflictaffiliative interaction between former opponents. • Occurs in many primate and some nonprimate species. • Reconciliation apparently repairs any damage to relationships between opponents disturbed by the previous conflict and reduces postconflict stress levels.

3. Background on Consolation • Consolation: affiliation directed from a third party toward the recipient of aggression. • Occurs in: great apes, dogs, large-brained birds. • Does not occur in: monkeys. • Consolation may represent an intermediate level that corresponds with ‘‘sympathetic concern’’ in developmental psychology.

4. Conclusion of background information • No evidence that consolation helps reduce stress • limited evidence that consolation serves as a substitute for reconciliation. • Only two studies (Koskiet al. (29) and Wittig &Boesch(12)), both on chimpanzees, focused on the relationship between the former opponents and not on the relationship with potential consolers.

5. Hypotheses If consolation also has a stress-reducing function, rates of self-directed behaviors should decrease after its occurrence. Due to social determinants of consolation, If the inter-opponent relationship is poor, then reconciliation is less likely so occurrence of consolation is more likely . If good relationship quality between the initial recipient of aggression and potential consolers then the rate of consolation should increase. The only study that has tested this hypothesis found no support for a stress-alleviating effect(15).

6. Participants • A total of 234 PC–MC pairs were collected on 22 recipients of aggression involving 129 distinct aggressor–recipient dyads (mean +/ SD PC–MC pairs per recipient= 10.6 5.7; range =2–25). PC: Post conflict observations MC: Matched-control observations the group size varied from 26 to 32, with 17 adult females, 5 adult males and 4–10 juveniles and infants. All adults were present throughout the study and constituted the study subjects.

7. Method 1 Comparison: matched-control self-directed behavior Does aggressive conflict lead to increased post conflict stress levels? • post-conflict self-directed behavior (no reconciliation/consolation)

8. Results 1 Self grooming Self scratching • Levels of self-directed behavior for PCs without reconciliation and consolation were higher than levels for MCs (p<0.001).

9. Method 2 Compare: post conflict self-directed behavior (with consolation) Does consolation (in the absence of reconciliation) decrease post conflict stress levels? • post conflict self-directed behavior (no reconciliation/consolation)

10. Method 2 Consolation with/without reconciliation occurrence of consolation with reconciliation. Compare: • occurrence of consolation without reconciliation

11. Results 2 • PCs after consolation had a significantly lower level of self-directed behavior than PCs without consolation or reconciliation (p= 0.009). • Reconciliation had a negative effect on consolation (p=0.013), indicating that consolation was more likely to occur in the absence of reconciliation. (GLMM)

12. Method 3 Does consolation (in the absence of reconciliation) decrease post conflict stress levels? self-directed behavior occurred after consolation Compare: • self-directed behavior occurred before consolation

13. Results 3 • Levels of self-directed behavior before consolation were found to be significantly higher than levels after consolation had taken place (p= 0.009).

14. Determinants of Consolation • Relationship quality: • Value: fitness benefits-high positive loadings of variables including the proportion of time spent grooming, the frequency of food sharing, and frequency of agonistic support. • Compatibility: tolerance-negative loadings from variables including the rate of counter intervention, aggression, and negative responses to approaches. • Security: consistency-high positive loadings from variables including the consistency of affiliation and symmetry in proportion of time spent grooming.

15. Relationship on occurrence of consolation: Factors affecting the occurrence of consolation were investigated by using GLMMs, an extension of LMMs, which enable models to be fitted with dichotomous dependent variables, in this case the presence or absence of consolation.

16. Relationship on occurrence of consolation: Consolation index for each dyad = frequency of consolation/ opportunity to console. Consolation index does not control for baseline levels of affiliation between partners, a further analysis was conducted by using the TCT TCT for each dyad =(attracted pairs - dispersed pairs)/(attracted +dispersed + neutral pairs).

17. Results 4 Recipients of aggression were more likely to be consoled by individuals with whom they had a more valuable relationship (p=0.002).

18. Conclusion 1 Levels of self-directed behavior for PCs without reconciliation and consolation were higher than levels for MCs (p<0.001). No reconciliation or consolation = higher PC stress

19. Conclusion 2 Levels of self-directed behavior were not significantly different for PCs after consolation and MCs (p=0.139).  Consolation decreases self directed behaviors to Matched-Controls level. Not complete repair of relationship.

20. Conclusion 3 • Levels of self-directed behavior after consolation were found to be significantly lower than levels after PC without consolation or reconciliation (p=0.009). • Levels of self-directed behavior before consolation were found to be significantly higher than levels after consolation had taken place (p= 0.009). Less self-directed behavior after conflicts after consolation occurred. Implies stress-alleviating effects of consolation.

21. Conclusion 4 Recipients of aggression were more likely to be consoled by individuals with whom they had a more valuable relationship (p=0.002).  Increased quality of third party relationship = increased likelihood of consolation

22. Hypotheses If consolation also has a stress-reducing function, rates of self-directed behaviors should decrease after its occurrence. Examine the social determinants of consolation – consolation is more likely to occur in the absence of reconciliation. Investigated the effect of relationship quality between the initial recipient of aggression and potential consolers on the rate of consolation.

23. Discussion Consolation is critical behavior that reduces distress. Bystanders may derive greater benefits from consoling valuable partners. Only reconciliation can repair the relationship between opponents. Consolation can serve as a partial alternative when reconciliation is not worthwhile. Consolation of other species may serve different functions. Some species may be more sensitive to the stress levels of others.

24. Areas of Further Study Additional measures of stress. Consequences of long-term high stress levels. Bystander’s behavior and emotional state. Benefits of consolation among the group. Consolation as part of mutualistic behavior/reciprocity. Differentiate between postconflict event and empathetic behavior.