Common Chimpanzee

Species: Pan troglodytes. 3 subsp. W. Africa, C. Africa, E. Africa.

PHYSICAL DESCRIPTION: Male Ht. 3.6-4.4 ft., Wt. 85-120 lbs. Female Ht. 3.0-3.8 ft., Wt. 60-90 lbs. Coat: Black to brown-gray, turning gray with age. Baldness frequent in adults. Skin black on hands and feet, variable pink to brown on face. Large brains (300-400 cc). Quadrupedal knuckle-walking. Longevity: about 40 years in wild.

GEOGRAPHIC LOCATION: West and Central Africa

ECOLOGY: Semi-terrestrial frugivores. Prefer secondary forests, but occupy a variety of habitats from dense rainforest to dry, open savannah. Home range: 10 - 50 km2 Day range: 1 - 5 km. Population density: variable, approx. ..5 - 5.0 / km2

DIET: Fruit (figs...), seeds, flowers, soft pith, young leaves, some meat (5%). About 20 species/day, 300/yr. of plants are eaten.

SOCIAL ORGANIZATION: Multiple-male polygynous groups (12-50 individuals, avg. 20), no solitary individuals. Primarily female transfer. Variable female dominance hierarchy, significant female ties among mothers and daughters. Fairly stable male dominance hierarchy, involving complex coalitions (see de Waal reference below). Territorial defense by male "boundary patrols." Females forage by themselves, occasional group feeding in fruit trees, sometimes initiated by "food calls" given by males that have located a food bonanza. Aggression among females is uncommon, but male-male conflicts are more frequent, usually involving multiple individuals. "Reconciliation" (e.g., touching, grooming) is common after within-group conflicts. Inter-group conflicts can result in the extermination of one group by another (Mahale). Highly intelligent, self-aware, apparent purposeful deception of others, sophisticated social manipulation tactics. Complex communication system, with at least 13 different calls, and many complex non-verbal signals. Many types of tool use, including sponges, wipes, termite probes, stone hammer/anvil, weapons, and grooming devices. Use several medicinal plants.

REPRODUCTION: Little birth seasonality. Males sexually mature at 16 yrs., females at 12 yrs. Gestation length: 8.0 months. Obvious estrus swellings for about 8/35 days. Copulation duration approx. 8 secs., ususally ventro-dorsal. Few or no pre-copulatory signals. Litter size: 1. Interbirth interval: 4 yrs. Infant birth wt.: 5 lbs. 40% infant mortality in first 3 yrs.

PARENTAL CARE: Infants carried by females for 1-2 yrs. Walk at about 9 months. Weaning at 3 ys., but offspring stay with mothers until thay are at least 6 years old. Long term relationships between mothers and offspring exist, even into adulthood.

TOPICS OF SPECIAL INTEREST: Linguistic and cognitive abilities, "warfare," comparisons with humans (they are our closest phylogenetic relatives).

BIBLIOGRAPHIC SOURCES:

Goodall, Jane 1989. The Chimpanzees of Gombe. Cambridge: Harvard.

de Waal, Frans 1990. Peacemaking among primates. Cambridge: Harvard.

Wrangham, R.W. et al. 1996. Chimpanzee Cultures. Cambridge: Harvard.

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