The "subject" is not only willing to share, but goes to the trouble of unlocking another Bonobo's cage to make sure his pal can also get to the food. Compare with the following description of Aka Pygmy sharing, by Michelle Kisliuk:
On another occasion I brought a tomato to the Bagandou camp . . . I gave a wedge to Bandit sitting beside me, expecting him to pop it in his mouth. Instead, he proceeded to call for a knife and cut the wedge into about sixteen tiny pieces, sharing it with everybody in sight (Seize the Dance, p. 132).One of the points Savage-Rumbaugh stresses (in the presentation linked to in the previous post) is that the remarkable behaviors of the Bonobos she works with appear to be cultural rather than simply instinctive. Which raises the question of whether Bonobo sharing, and other types of cooperation (including interactive vocalizing) represent learned traditions or biologically determined behaviors. As in many other cases, elements of both may play essential roles.
Since the sharing of food and other useful items is a hallmark of both Pygmy and Bushmen behavior, I included "the sharing of vital resources" as one of the "core values" of HBC, the (hypothetical) baseline culture of the ancestral group from which all contemporary humans are descended (to learn how this baseline was derived, see Posts 228 et seq.). If my hypothetical baseline is accurate, it seems likely that our earliest human ancestors may have been more like Bonobos than Chimps (who do not share) or other primates, which makes the (apparent) similarities between Bonobo hooted "duetting" and "chorusing" and Pygmy/Bushmen yodeled hocketing (see post 328, below) especially interesting. Of course, there are many other notable similarities between Bonobo "culture" and HBC, including female assertiveness, non-hierarchical political structure and a tendency to non-violence.
I haven't yet had an opportunity to actually listen to any example of interactive Bonobo hooting, but the reports by de Waal and others seem convincing. However, in a more recent article than the one I quoted earlier, Björn Merker surprisingly appears to reverse himself with respect to Bonobo vocalizations, pointing to "a number of other specieis, none of them closely related to humans, that also engage in group synchrony of behavior through entrainment to an isochronous pulse" (my emphasis -- Merker et al, On the role and origin of isochrony in human rhythmic entrainment, Cortex 15, 2009).
Merker refers to de Waal's research, but appears reluctant to make too much of it since the Bonobos he studied were in captivity:
A vocal rather than a manual source for the crucial isochrony underlying musical rhythmicity is hinted at by the vocal behaviour of bonobos called ‘‘staccato hooting’’ (DeWaal, 1988, pp. 282–283; Bermejo and Omedes, 1999). To date, it furnishes the only indication that a great ape may be capable of entrainment. The repetitive hooting is paced at roughly 2 Hz (i.e., in the range of rhythmic music, see Moelants, 2002), and is reported to include inter-individual synchrony of hoots (De Waal, 1988). Few issues would seem to provide more leverage for the comparative study of the biology of human musical rhythmicity than a thorough characterisation of bonobo staccato hooting in the wild. Should it occur, and serve inter-individual entrainment of voices, the genus Homo would not be alone among the apes in having evolved a capacity for rhythmic entrainment of voices. (my emphasis -- p. 7)
Merker appears unaware of earlier research by Gottfried Hohmann and Barbara Fruth, whose studies of Bonobos in the Lomako Forest of Central Zaire emphatically confirm de Waal's observations:
From analyses of simultaneous high- hootings of mature pairs, it became apparent that calls of both apes were given often in more or less perfect alternation, indicating a remarkable degree of behavioral coordination between them. Jordan (1977) and de Waal (1988) mention a high degree of synchronization between vocalizations of different individuals, and the latter author emphasized the gibbon-like nature of long-distance hooting. (Structure and Use of Distance Calls in Wild Bonobos, 1994).
(to be continued . . . )