G R A D E 1 2M . C A R D I N A L
CHIMPANZEES: OUR CLOSEST RELATIVES
TWO SPECIES OF CHIMPANZEE
• Pan troglodytes – common chimpanzee• 35 – 50 kg
• Pan paniscus – bonobo• 32 – 40 kg
• Found across central Africa
• Both species eat mainly fruit
SOCIAL ORGANIZATION
• Live in communities from 20 to 150 individuals
• Fission-fusion social pattern• Individuals spend time in various subgroups
• Both species have mostly male phiopatry
• Subgroup size is connected with fruit availability
DOMINANCE: PAN TROGLODYTES
• Male are more dominant than females
• Both males and females compete with other of their sex for hierarchical ranks
• Male competition for rank can result in injuries and sometimes death
• High ranking females have more offspring in their group
• Females rarely fight for dominance
DOMINANCE: PAN PANISCUS
• Females more dominant than males
• Rarely any fights for dominance
• Engage in sociosexual behavior• Nonreproductive sexual behavior that serves to resolve
conflicts and/or reinforce alliances and coalitions
• Males rank is tied to his mother
SEXUAL BEHAVIOR
• Females have distinct signs of fertility
• Swellings attract interest from other members in the community
• Females mate with multiple males
• Males attempt to mate-guard females in Pan troglodytes
• Pan paniscus engage in sexual activity outside the estrus
HUNTING AND MEAT EATING
• Both species eat other mammals
• Pan troglodytes do more than Pan paniscus
• Make up about 5% of diet
• Females hunt in both species
• Mostly males hunt in Pan troglodytes
• The larger the group hunting = more success
• Very few get to eat the killed
• Higher ranking chimpanzees may steal the kill from a lower ranking chimpanzee
GROUP AGGRESSION
• Some conflicts result in death in Pan troglodytes
• Groups of males move along community borders searching for subgroups or individuals from other communities
• Attack together when they find others
• May be to increase their range and resources
TOOL USE
• Chimpanzees have the widest variety of tool use and modifications
• Other than humans
• Tools used to extract food
• All populations use tools, just differently
• Some groups don’t use tools that other groups may use
• Both males and females use tools
SOCIAL TRADITIONS
• Behaviors that have a learned component and are frequently nonfunctional
• At least 39 different social traditions have been documented• Example: holding hand together above their head during
grooming
• Varies by region and community
CLASS ACTIVITY
SIMILAR TO HUMANS
• Subgroups and communities
• Sex in social context and male-bonding related to aggression, similar to our close relatives
• Acquiring meat and other foods and sharing with other members
• Sexual aggression, mate guarding, and aggression towards others may be similar to rape, marriage laws, and wars
• Wide variety of tools
SUMMARY
• Chimpanzees exhibit numerous traits that are similar to humans from: behavior, social interactions, and tool use
• Although chimpanzees are our closest relatives, we have been evolving differently for the past 6 million years