Sonso culture 81The Sonso chimpanzees share a large number of cultural features with chimpanzees
at other sites, among them the following (Whiten et al. 1999):
● Play start (invite play holding stem in mouth)
● Drag branch (drag large branch in display)
● Leaf-sponge (leaf mass used as sponge)
● Branch-clasp (clasp branch above, groom)
● Branch-shake (to attract attention, court)
● Buttress-beat (drum on buttress of tree)
They also have some which are shared with some other sites but not all. These more
particular cultural features of the Sonso chimpanzees (Whiten et al. 1999) are as
follows:
● Food pound on to wood (smash food)
● Fly-whisk (leafy stick used to fan flies)
● Leaf-napkin (leaves used to clean body)
● Leaf-groom (intense ‘grooming’ of leaves)
● Leaf-clip, mouth (rip parts off leaf, with mouth)
● Leaf-clip, fingers (rip leaf with fingers)
● Leaf-inspect (inspect ectoparasite on leaf placed on arm or hand) (Assersohn et al.
2004)
● Branch-slap (slap branch for attention)
● Shrub-bend (squash stems underfoot)
● Rain dance (display at start of rain)
Precise definitions of these items are provided in Whiten et al. (2001), in some cases
based on the very detailed ethogram of the Mahale chimpanzees (Nishida et al. 1999).
More items, e.g. pocket-tuck (placing an object in a body fold of groin or neck and moving
around with it held there — see below) are being added to the Sonso repertoire as time
goes by. Interesting questions arise about the distribution of culture traits. Nut-cracking
is exclusive to West African chimpanzee culture, and leaf-grooming is exclusive to East
Africa. The role played by diffusion is explored in a paper (Whiten et al. 2001), and so
also is the evidence for multiple origins. One item of culture is particularly indicative of
multiple origins: the grooming hand-clasp (McGrew and Tutin 1978). In this behaviour,
two individuals clasp hands overhead, grooming each other with the other hand.