Hominoid Psychology Research Group

What is a Bonobo?

Our Two Closest Relatives

Bonobos and Chimpanzees are BOTH our closest relatives

Both species are members of the "chimpanzee" genus Pan and both represent our species closest living relative. How can humans have two closest relatives? Similar to how two aunts or cousins are different from one another but equal in their genetic relation to you.

Bonobos and Chimpanzees both share close to 98% of their genome in common with humans, meaning that their genomes are more similar to that of humans than they are to that of gorillas. Surprise! Even though they appear to be more similar to gorillas they are more closely related to us.

Our two closest relatives are also different from each other

Even though the two species are equally related to humans, the two species differ from each other in important ways that can help us understand our own species evolution. Bonobos and chimpanzees diverged from each other < 1 million years ago and differ significantly in morphology, behavior, emotions and cognition.

The Bonobo

Bonobos are female dominant, with females forming tight bonds against males through same-sex socio-sexual contact that is thought to limit aggression. In the wild, they have not been seen to cooperatively hunt, use tools, or exhibit lethal aggression.

The Chimpanzee

Chimpanzees are male dominant, with intense aggression between different groups that can be lethal. Chimpanzees use tools, cooperatively hunt monkeys, and will even eat the infants of other chimpanzee groups.

Below is a detailed comparison of the two species

Pan paniscus

Pan troglodytes


slender build, bright pink lips, black face, smaller and juvenilzed brain case in males

robust build, face color changes with age, dark lips

Natural Distribution

only endemic to Democratic Republic of Congo in Congo Basin south of the Congo River (no subspecies)

only found North of Congo River in Democratic Republic of Congo with three subspecies distributed across East, Central and West Africa in over 12 countries

Sexual Dimorphism

less sexual dimorphism

more sexual dimorphism

Social Organization

fission-fusion societies:

- typically larger daily party size than chimpanzees
- live in 'communities' of multiple males and females and their offspring
- mother-son and female-female bonds very important

fission-fusion societies:

- live in 'communities' of multiple males and females and their offspring
- different group composition
- male-male bonds very important while female-female bonds typically weak


- higher pitched
- peeps and peep yelps
- males drum on tree buttresses

- lower pitched
- hoot, scream, grunt
- males drum on tree buttresses

Dominance Hierarchy

- females form strong bonds with weak hierarchy and in coalitions can dominate males
- male is never alpha/highest ranking individual

linear set of relationships among all males which includes a clear alpha-male (or coalition of males)

Group Hunting

extremely rare, if ever

frequent in times of abundant fruit, when multiple chimpanzee males and red Colobus monkeys plentiful


- no evidence of lethal aggression in defending home ranges
- mating across community lines occasionally observed

- specific territories
- aggressive patrolling of boundaries can result in lethal aggression (killing of neighbors)
- avoidance of neighbors

Tool Use

only frequently seen in captivity

cultural variation exists that is transmitted through social learning, compared to other animals relatively complex nut cracking, ant fishing, leaf clipping & medicinal plant use observed

Sexual Behavior

- frequent non-reproductive sexual behavior observed at all ages and between all partner types
- believed to reduce tension and encourage tolerance
- sexual excitement often observed during feeding
- frequent homosexual interactions especially in females
- used as a greeting and conflict resolution

- very little sexual behavior observed in adults outside of reproductive contexts
- high ranking males monopolize and guard females in estrus


hunting, snares, habitat destruction, infectious diseases

hunting, snares, habitat destruction, infectious diseases