18. Darwin The Descent of Man (1871) “ The following proposition seems to me in a high degree probable – namely, that any animal whatever, endowed with well-marked social instincts, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become well developed, or nearly as well developed, as in man” (chapter III, p71) “ Thus the social instincts, which must have been acquired by man in a very rude state, and probably even by his early ape-like progenitors, still give the impulse to many of his best actions” (chapter III, p86)
42. Aggressive behavior is only one of several ways in which conflicts of interest can be settled. Other possible ways are tolerance (e.g., sharing of resources), or avoidance of confrontation (e.g., by subordinates to dominants).
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45. Weaning A weaning compromise has been arrived at between a mother chimpanzee and her 4-year-old son. After repeated nursing conflicts, the son is permitted to suck on a part of the mother's body other than the nipple.
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49. Reconciliation Other evidence of an evolved moral sense can be seen in what happens after a conflict occurs. The nature of the social relationship determines whether repair attempts will be made, or not.
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51. Kiss to make-up Fig. 2. Chimpanzees typically seal a postconflict reunion, or reconciliation, with a mouth-to-mouth kiss, as here by a female (right) to the dominant male. De Waal, F. B. M. (2000). Primates--a natural heritage of conflict resolution. Science, 289 (5479), 586-590.
52. Most primates show a dramatic increase in body contact between former opponents during post conflict (PC) as compared with matched-control (MC) observations The cumulative percentage of opponent-pairs seeking friendly contact during a 10-min time window after 670 spontaneous aggressive incidents in a zoo group of stumptail macaques
53. Reconciliations allow rhesus monkeys to maintain tight kinship bonds despite frequent intrafamilial squabbles. Shortly after two adult sisters bit each other, they reunite sitting on the left and right of their mother, the alpha female of the troop, each female holding her own infant. The sisters smack their lips while the matriarch loudly grunts.
54. Capuchin fairness study: Brosnan, S., and F. B. M. de Waal. 2003. Monkeys reject unequal pay. Nature 425:297-299.
55. Brosnan performed a lab experiment in which capuchin monkeys are given a small token (a rock) that they can then return to the experimenter in exchange for a food reward. They like cucumbers alright, but grapes are the really preferred reward. Two capuchins were situated side-by-side in visible but not physical contact of each other, both were presented with an exchange opportunity in turn, and the second monkey’s reaction was the focus of the experiment. Separately both individuals had very high rates of successful exchange.
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57. This is suggested to perhaps be a sense of “fairness” or “justice”. Males didn’t seem to care either way, but female subjects tended to refuse the inequality cucumber exchange – they either refused to take the cucumber or they took it and then quickly threw it back at the experimenter. Thus they conclude that capuchin females pay more attention to the value of exchanged goods and services and are willing to sacrifice a small gain when their neighbor gets a greater reward. Is this due to spite?
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