Dec 09 2009
The Bonobo: A Peace and Love Primate
Rather the the apparently more brutish chimpanzee, does the bonobo provide better clues to our innate behavioral heritage?
In their monograph, “African Apes As Time Machines,” (7) R. Wrangham and D. Pilbeam point out distinctive bonobo traits, features seemingly shared with our kind, including these five:
1. extensive non-conceptive sexuality
Bonobos “do it” even when offspring will not be the result. Females remain sexually active when not ovulating.
Humans? Ditto.
2. friendship among adult females
Female bonobos have relatively extensive, non-direct-kin social relations.
Human females? One need not tune in to The View to find evidence of this.
3. relatively egalitarian males
While male chimps are clearly hyper-attuned to individual status within the troop — the pecking order and all that — male bonobos don’t show the same preoccupation, at least not to the same degree. The difference between the big male of their patch of jungle and the lesser males is not as great.
Human males? Under many conditions that is definitely the case.
4. sexual conciliatory behavior
Two bonobos, even same-sex females via clitoral-rubbing, will use sex as a means of patching up a temporarily torn relationship.
Humans? Already established couples certainly seem to engage in what has been called “make-up sex.” But casual sex for the purpose of relationship repair?
5. potentially relaxed intergroup interactions
When two chimpanzee groups meet, the males typically go apoplectic. There is a great ruckus, with threat displays breaking out. Bonobo males are not equally xenophobic.
Human males? I suppose it depends upon the circumstance.
Besides behavioral traits, are bonobos more human-like than chimpanzees in terms of any physiological characteristics? Actually, the bonobo does have some physical traits that suggest closer kinship to our kind.
In her monograph, “Reconstructions reconsidered: chimpanzee models and human evolution,” Adrienne Zihlman points out these three (8):
1. smaller facial and canine measures
Bonobos have smaller canines than chimpanzees. And those of humans are even smaller.
2. smaller body size
Relative to chimps, human bodies are proportionately long on limbs. Same with bonobos.
3. relative limb length
Bonobos have longer legs relative to their arms than do chimps. Same with humans. Both humans and bonobos, not coincidentally, have greater bone density in their legs (femur and tibia) than do chimpanzees. And relative to chimpanzees, bonobos are much better at bipedal standing and locomotion.
Chimp expert extraordinare, Frans de Waal, has recognized the significant physiological similarities (relative) of the bonobo and human.
“The bonobo’s body proportions, especially its relatively heavy legs, are closer to those of Australopithecus than the proportions of any other living ape. Bonobos stand and walk on two legs more often, and with greater ease, than common chimpanzees, who do not straighten their backs as much.” (10)
But maybe the kinship is only skin-deep. What about behavior?
In upcoming posts we will take a look at the different behaviors of bonobos as they pertain to both sex and ingroup harmony as well as out-group relations (reaction to foreign conspecifics). Finally, we’ll end with reasons for caution and doubt when considering crowning the bonobo as the preeminent proto-human.
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(7) Wrangham, R. & Pilbeam, D., “African Apes As Time Machines,” in Galdikas, B. M. F., Briggs, N. E., Sheeran, L.K., Shapiro, G. L. & Goodall, J. (Eds.), All Apes Great and Small, Volume I: African Apes, Kluwer Academic / Plenum, New York, 2001, p.13
(8) Zihlman, A., “Reconstructions reconsidered: chimpanzee models and human evolution,” in McGrew, W. C. , Marchant, L. F. & Nishida, T., Great Ape Societies, Cambridge University Press, Cambridge, UK, 1996, p. 297
(10) de Waal, F. Peacemaking Among Primates, Harvard University Press, Cambridge, MA, 1989
p. 181
