common Pan troglyodytes
perhaps three varieties
Pan P also is somewhat smaller, more juvenile in appearance, and displays less sexual dimorphism.
Plant foods appear to be more important for Pp than Pt--they both are basically frugivores when possible with wide variation according to conditions. Pan p. has been observed eating beetles, grubs, snails, snakes, shrews, and the rare young infant duikers (deerlike critters). Kano and Mulava (, p.269) 1984) in The Pygmy Ch.. report that while p.t at Gombe spend 43% of their time eating, p.p spends only 30% at most.
de Waal notes the bonobo's great use of non-reproductive sex and their lesser aggressiveness compared to their close chimp cousins. This is not to say they are not aggressive. He notes, citing Kano (1984) that a number of males have been observed without testicles and males have far more injuries than females. p.189. He also notes the female dominance may have lessened some of the inter-group aggression observed by Goodall in the common chimps. "Once copulation between malesa nad females of different communities occur on a regular basis, this may reduce male competition over territories and the females contained therein....their competitors may be their brothers, fathers, sons...and fighting not necessary to gain access to females....In short, sexual relations between groups may have removed some of the evolutionary advantages that males gain from intergroup warfare...189"
In his observations at the San Diego zoo, de Waal noted 698 sociosexual interactions between bonobos in addition to 39 instances of masturbation -- many involving same-sex combinations and immature apes. Ventral-ventral mounting (81%) and GG rubbing (52%) was very common. Kissing and oral sex were less frequent in the same-sex relations (5-10%) but quite widespread.
He cites Vauclair and Bard's(1983) comparative study of object manipulation in infant humans, chimps, and bonobos. While the human did more complex manipulations, the bonobo used its feet much more than either the human or chimp.
Unlike other apes, it seems that female bonobos
can "outrank" males in some circumstances. de Waal wonders "whether this
female dominance is based on female alliances, male inhibitions, or seniority
(female bonobos probably grow older than males..p. 188).
|Bonobo Life Stage (female)
||Age in years (approximately)|
|First genital swelling (puberty)||7|
|Begins to wander between groups||8|
|Settles into new group||9-13|
|Menarche and first full swelling||10|
|Full adult size||14-16|
|Cessation of ovulation (menopause)||40|
|Number of offspring up to 6||between 13-40|
(above based largely on data in de Waal (1997, p. 190).
de Waal, F. (1997). Bonobo: the forgotten ape. Berkeley: University of California.