Physical and Behavioral Attributes of Bonobos: Differences Between Pygmy Chimpanzees and Other Great Apes

Bonobos, or pygmy chimpanzees (Pan paniscus), live in the tropical forest region of Congo. Since their discovery, debate has ensued over whether or not pygmy chimpanzees are a distinct species or a subspecies of the common chimpanzee. Whatever the case, bonobos do possess a substantial number of physical and behavioral characteristics that are distinct from those of common chimpanzees.

Physical Differences

Bonobos and chimpanzees differ in their skull size and shape, with the bonobos’ being smaller. Bonobos have a lower body weight and also differ from chimpanzees in sexual variation / dimorphism (bonobos being less dimorphic), and blood type.

Behavioral Differences

Behaviorally, bonobos differentiate from common chimpanzees in terms of social groups and patterns, food and nutrition, sexual behavior, and social relationships.

Social Groups

In general, the social groups of pygmy chimpanzees are larger than those of common chimpanzees. As well, pygmy groups are more stable and aggregative than those of common chimpanzees; conflicts are resolved more peacefully and the individual survival rate is higher.

Food and Nutrition

In terms of food, common chimpanzees seem to eat a larger quantity and variety of food types. It is unclear, however, whether or not this is a result of the diversity and amount of food available in the two species’ respective habitats. Common chimpanzees, for example, “exploit a wider ecological range to obtain food than pygmy chimpanzees and have developed a higher degree of technical skills. Conversely, the food acquisition skills of pygmy chimpanzees are primarily for obtaining fruits in high trees” (Kano 1992, p. 137).

Sexual Behavior

Bonobos are also unique in their patterns of sexual behavior. Females are nearly always sexually receptive, have friendships with males and other females, and are sexually promiscuous. As a result, there is little sexual competition among males, particularly compared to common chimpanzees.

Social Relationships

Social relationships are more coherent among bonobos. Unity among males is less strong than in common chimpanzees; however, relationships among females and between male and female bonobos are much friendlier than in common chimpanzees (Kano 1992, p. 205). In general then, pygmy chimpanzees have large, stable groups made up of nearly equal numbers of males and females. In contrast to common chimpanzees, bonobos are passive, do not engage in all-male war parties, and have never been witnessed to carry out infanticide (Kano 1992, p. 209; Rumbaugh 1998, p. 3).

Given the stark differences between chimpanzees and bonobos, researchers have been anxious to examine whether or not bonobos would demonstrate a higher (or lower) capacity for human language learning. Because of their temperament and inquisitive nature, it has been proposed that they may be better adept at language training tasks and it has been suggested that bonobos are more intelligent than common chimpanzees.