Know Your Primate: Pan paniscus

Know Your Primate grew out of posts I wrote specifically for the Friday Ark back on my old blog. The point was to write short, informative posts about whatever species struck my fancy (and at that point was not limited to primates). Once I moved to ScienceBlogs those kind of posts went by the wayside. Then in July, 2006 I decided to resurrect the idea with a specific focus on primates. In the time since I have focused on a wide variety of primates but, with one or two exceptions, have avoided the extant apes. This is largely due to the explosion of knowledge about them in the past 10-15 years, which makes it hard to write a short post in the format I have chosen for this series. Bearing that limitation in mind, here is this weeks primate.

Order: Primates
Suborder: Haplorrhini
Family: Hominidae
Genus: Pan
Species: Pan paniscus
Common Name: Bonobo, pygmy chimpanzee
Bonobos mainly reside in the Democratic Republic of the Congo. They reside in tropical rainforests and swamp forests. They are, arguably, the most fascinating of the great apes. Because of their anatomy they have been used as a model for the common ancestor of chimps and humans (molecular evidence indicates that they split off from the chimps approximately 1.6 MYA), they have been used in a wide variety of experiments relating to language, and, of course, there is the sex – which is frequently used to help group cohesion:
(Picture source Natural History Museum, University of Oslo, Norway, Two female bonobos, Pan paniscus, rubbing their genitals together with some family attendance.)
But there is more to bonobos than sex. They are about the same size as their cousins, the common chimps, although body proportions differ. For example, they have a more gracile skull, longer, more slender limbs, a smaller chest, and longer hands and feet than the common chimp. Like the common chimp, they are primarily knuckle-walkers (which reminds me, I need to get back to work on my series on primate locomotion), but they also engage in bipedal walking, leaping, and brachiation (they engage in more suspensory behavior than any other ape). In short, they have a very complex locomotor repertoire.

Bonobos eat fruit, leaves, insects, snakes, fish, and the occasional duiker. Bonobos have the same fusion-fission community structure as chimps and seem to be somewhat more gregarious. Group size ranges from 40-120 individuals, although subgroups of around 15 individuals are common. Groups revolve around a female, her subadult male offspring and and adult female associations. Consequently, dominance tends to revolve around females. In bonobo society subadult females leave the group they are born in. Grooming is most frequent between males and females with grooming between females being the second most frequent. This is unlike the pattern seen in the common chimpanzee (male-male most common) and gorillas (male-female most common, but female-female grooming hardly ever occurs). Bonobo society, then, seems to be organized around a completely different sent of concerns from either common chimpanzee or gorilla society.

Then of course, there is the sex. As the Animal Diversity Web explains:

A major focus of research on bonobos centers around their use sexual behaviors in non-reproductive contexts. These non-copulatory behaviors include female-female contact (genito-genito-rubbing, or GG rubbing), male-male contact (mounting and rump contact), and a long period of juvenile and adolescent copulation mimicry (albeit without intromission). A large amount of the research has been to document the frequency of each behavior between every pair of group members. These behaviors are observed in females particularly upon entering a new group after leaving their natal group, and at feeding locales where a large quantity of food is encountered. These sexual behaviors may be a way of negotiating and enforcing status differences within both females and males.