GRADE 12 M.CARDINAL 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