Groups studied in the comparative analysis of. culture. Source: Cultures in Chimpanzees Nature, 399, (1999)

Transcription

1 Chimpanzee Culture Evidence and Interpretation

2 Groups studied in the comparative analysis of chimpanzee culture Source: Cultures in Chimpanzees Nature, 399, (1999)

3 Chimpanzee Cultures An examination of 6 chimp research sites 39 behaviors were found to be either customary (occurs in at least one age or sex group) or habitual ( occurs repeatedly in several individuals) These 39 behaviors did not exist in all chimp groups

4 Type of Cultural Behavior Tool use: stones or branches for cracking nuts Social: greetings, rain dances, invitations to groom, and invitations to play Personal hygiene: use of sticks and leaves to clean body. Medical: use of plants to treat parasites and infections

5 Interpretations Some behaviors did not exist for ecological reasons. For example, use of stones to smash or crack nut is found only in areas where stones exist. Behaviors unique to one group are clearly a consequence of cultural transmission Behaviors common to several groups may be a consequence of common ancestry, independent invention, or diffusion (females moving between groups).

6 Mechanisms of Transmission: Teaching and Learning Facilitation (stimulus enhancement): leaving nuts, anvil, and hammer in view of offspring Active teaching (social enhancement): a mother does the behavior slowly so youngster can observe. As youngster tries, repositioning of hand or nuts by mother. This is very rare. (Recent theory suggests that even thought this may occur the youngster receives no feed- back from teacher.) Highly social chimps appear to have greater cultural repertoires because they interact more than solitary orangs. Diffusion of culture: : immigrant mother teaches infant tool using techniques she learned in natal group

7 Types of Learning Emulation: a rough replication of the behavior. Imitation: : precise replication of the behavior Chimps appear to always emulate while human children imitate. Rake example.

8 Tool use is a critical adaptation enhancing feeding efficiency In the Taï forest mother chimpanzees teach their infants the tasty art of nut cracking [the nut is Panda oleosa] ], which takes about seven years to master it takes about 2,200 pounds (1,000 kilograms) of skillfully applied force to split the nut without t pulverizing i it. Between February and August, the prime nut-cracking season, a practiced chimp can break open more than 100 nuts per day obtaining a nutritional kick of 3,000 calories. Source National Geographic:

9 Chimp Nut Cracking

10 Sponging and Mashing Figure 3 shows a compound tool

11 Termite Tool

12 Chimp archaeology: 4,300 year old tools Macrader et al., 2007 PNAS

13 Chimpanzee Spear Hunting Figure 2. Tip of Hunting Tool Sharpened with teeth Tool length approximately 70 cm. Savanna Chimpanzees, Pan troglodytes verus,, Hunt with Tools Jill D. Pruetz and Paco Bertolani. Current Biology 17, 1 6, March 6, 2007

14 Bush Baby (Galago senegalensis): prey of chimp spears

15 Chimpanzee Medicine Consumption of bitter plants to relieve constipation. The pith of Vernonia amygdalina is used both by chimps and humans (WaTongwe) as cures for a variety of bacterial and parasitic infections Infection of parasites drops noticeably after chewing of Vernonia amygdalina pith. Chemical analyses has revealed sesquiterpene lactones and new steroid glucosides with antiparasitic activity against Schistosoma, Plasmodium and Leishmania. Ill chimps swallow whole leave with bristly undersides which scrub their intestinal tract by mechanically picking up intestinal worms. Capuchin monkeys have developed their own insect repellent; by squirting millipede innards or rub particular leaves over themselves and each other.

16 Hand clasp grooming style: a culturally transmitted social convention

17 Chimp Infant Care