Perspectives
Although transfer of referential meaning is hindered in both species in
the wild,it does take place to a certain extent in the laboratory in human
surroundings.There,however,the species perform differently;that is,
laboratory results may reflect a species difference in communicative
skill not directly observable in the wild.Representatives of both species
understand and apply differences in meaning arising from different
word orders.The bonobo generalizes and,without further training,
is able to respond properly to several hundred pairs of utterances
(Savage-Rumbaugh et al.1993:91–97),whereas the common chimpanzee
trained by Premack did not appear to understand the general rule but
had to learn each case.
In a recent experiment,two female infants from each species and of
the same age were reared together in the same conditions.Compared
for their skill at comprehending spoken language, the bonobo
performed well above her chimpanzee peer (Brakke and Savage-
Rumbaugh 1995).
These performance differences in the laboratory strongly support the
view that the bonobo’s superior language skill is a species characteristic.
This superiority may also reflect species differences in social organiza-
tion.Although both chimpanzees and bonobos are primarily promis-
cuous in mating, among bonobos, long-term consortships between
particular males and particular females are common (Kano 1992).
Whereas in chimpanzees,as in most primate species,the reproductive
unit is essentially coextensive with the whole group, in bonobos,
temporarily separated reproductive units exist inside the group.This
structure results in a complex social network with sophisticated com-
munication patterns.
Moreover,the stronger male-female bonding in bonobos,which is
maintained by extended female sexual receptivity,may be linked to
greater preservation of ancestral territorial song.This is indicated by
duetting between males and females,characteristic of primate territorial
song (Haimoff 1986),and by more variable vocal performances com-
pared with chimpanzees.As noted by de Waal (1988),bonobos show a
high degree of synchronization,with duetting reminiscent in this respect
of gibbon duetting.
These alternative solutions within an essentially similar basic pattern
give some insight into a third possibility,which would join a bonobo-like
social system to a chimpanzee-like manipulative activity,supposedly in
the ancestor of the human lineage.In such circumstances an opportunity
arose to extend referential use of vocal elements across and beyond the131 Social Organization