What is a bonobo?
The bonobo (Pan paniscus) is a great ape most closely related to the chimpanzee. It is the least known of the great apes because it lives in a remote rain-forest region of central Africa, and was only identified as a species in 1933. Although often referred to as the pygmy chimpanzee, pygmy is a misnomer because the body weight of the bonobo is, on average, the same or slightly less than that of the eastern common chimpanzee (Pan troglodytes schweinfurthi). Compared to the common chimpanzee, the body weight of the bonobo is proportioned differently; the center of gravity is lower, making it possible for the bonobo to stand more erect and walk bipedally (on two feet). Bonobos have longer limbs (relative to trunk length) and their build is generally more slender and graceful than chimpanzees. The lanky body structure of the bonobo is thought to be an adaptation for climbing and living an arboreal (living in the trees) lifestyle in the rain-forest. The head and ears of bonobos are noticeably smaller, and there is less brow mass over the eyes than characteristic of chimpanzees. The facial skin is darkly pigmented, and the hair is black, usually parted in the middle of the head with bushy sideburns on both sides of the face. The bonobo's vocalizations are high-pitched squeals.
Because of the similar morphological traits (physical appearance) between bonobos and humans, some anthropologists consider the bonobo to be the best living prototype for the common ancestor of humans. While this controversy is unresolved, it has been established through molecular genetic analyses that the chimpanzee genus, Pan, is most closely related to humans and shares approximately 98% genetic identity. It follows that bonobos and chimpanzees share many human-like morphological, physiological and behavioral traits.
Bonobos are confined geographically to a small region in the Democratic Republic of Congo, in the Congo River Basin south of the Congo River.
Unlike the common chimpanzee, which lives in a variety of habitats, the bonobo is found primarily in lowland rain forests. Its lifestyle is more arboreal than other African apes.
Bonobos primarily feed on arboreal fruits, leaves and pith from stems. They are known to eat insects and hunt small mammals occasionally. Bonobos also have been observed to slap water up from a stream and eat either invertebrates or fish.
Photo by Mark Scheuber of the Milwaukee County Zoo.
Certain aspects of bonobo social organization differ from the chimpanzee and other great apes. Bonobos are most frequently found in mixed age and sex groups with adults, juveniles and infants of both sexes freely associating with each other. There is a less pronounced dominance hierarchy in the bonobo's social structure. Unique among great apes, bonobos display a greater prevalence of strong female-female bonding as opposed to the predominance of male-male bonding observed in common chimpanzees.
One special feature observed in bonobo society is the low level of aggression between individual bonobos. Bonobos are less apt to engage in physical conflicts and confrontations with other groups of bonobos. Their generally peaceful society is attributed to the evolution of a highly complex social system.
Photo by Mark Scheuber of the Milwaukee County Zoo.
Bonobos have developed a set of ritualized socio-sexual behaviors that are specific to their species. Sexual behaviors, displayed by individuals of all ages, have evolved to strengthen group cohesion. For example, mating is common between male and female adults even when the female is not fertile. There is also a higher frequency of homosexual behavior among bonobos of all ages (especially among adult females), and genital contact functions as social appeasement during times of group tension. Bonobos mature at about 7 to 10 years old in captivity, and at about 12 to 14 years old in the wild. Captive females give birth to one infant approximately every five years, and gestation lasts around eight months. While the infant is dependent on its mother for the first four years of life, its father and siblings are strongly associated family members.
The Red Data Book, published by the International Union for the Conservation of Nature and Natural Resources, lists the bonobo as endangered due to exploitation by humans and loss of habitat. There are no valid estimates of the number of bonobos remaining in the wild. What is known is that bonobos no longer occur in much of their historical range. Wild populations have been reduced greatly by deforestation and human encroachment, and bonobo populations are discontinuous and widely scattered.
Threats to Survival: Even historically the bonobo has been considered to be a rare species relative to other apes because of its habitat limitations and small range. The bonobo is threatened by rain-forest destruction and is hunted for food and sale to the pet trade. Most recent reports from field researchers indicate increased poaching of bonobos for food. The increase in poaching of bonobos, and of all wildlife in the region, for food is attributed to nationwide food shortages and an influx of weapons and refugees from regional conflicts. One of the major threats to bonobos is that their range lies entirely within the country of the Democratic Republic of Congo. Thus the species is extremely vulnerable to political and social conflicts that may arise in Congo; the recent civil war has had an inestimable impact on Congo's wild bonobo population.
Bonobo and Congo Biodiversity Initiative