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Bonobo (Pan paniscus) Fact Sheet: Physical Characteristics

Bonobo (Pan paniscus)

Physical Characteristics

Body measurements

Attribute Males Females
Weight 39 kg (86 lb) 31 kg (68 lb)
Whole Body Length  700-800 mm (2.3-2.6 ft)

General Appearance

  • Black face, ears, palms and soles of feet; individuals in managed care may have lighter pigmentation.
  • Black body hair is long and fine.
    • Many adults retain the white rump tuft common to infants.
    • Hair on top of head appears to be parted down the middle.
    • Side-whiskers are long and thick.
    • Baldness does occur, although "perhaps later in life" than in other chimpanzees. (Groves 1989)
  • Compared to chimpanzee:
    • Brow ridges and facial bone structure are less pronounced.
    • Head is more rounded, with smaller ridges above eyes, less developed muzzle, less jaw protrusion..
    • More slender build, narrower chest, bone and muscle of lower limbs is heavier.
    • Ears smaller and almost completely covered by cheek whiskers.
      • Chimps' ears stand out more from the head
    • Molars smaller.
    • Less sexual dimorphism. (Cramer and Zihlmann 1978).
    • Lips are lighter, often reddish colored. (de Waal 2001)
    • Nostrils are "thick-walled" and more gorilla-like. (de Waal 2001).
  • In overall size, bonobos are not smaller than chimpanzees (most anatomical measurements overlap) but there are differences in proportion:
    • Bonobos have shorter upper limbs and longer lower limbs (Zihlmann 1996).
    • Compared to chimpanzees, bonobos have body characteristics that are better for bipedal or upright posture: (Myers Thompson 2002)
      • More centrally positioned opening in skull for spinal cord (foramen magnum)
      • Longer feet
      • Longer thigh bones
      • More body weight (heavier muscles) in lower legs of bonobos. (Zihlmann 1984)
    • Bonobos are quite similar in overall body size, cranial capacity, and lower limb length to an ancestral hominid, nicknamed Lucy, who lived some 3 million years ago in Africa. (Zihlmann 1984)

Other Physical and Physiological Characteristics

  • Of all the great apes, bonobos are the most human-like in their leg length. (de Waal 2001)
  • Bonobos share with humans a similar pattern of distribution of brain neuron cells called VENS (also called spindle cells or Von Economo Neurons). (Hakeem et al 2009)
    • VENs help regulate complex social interactions requiring knowledge of other individuals' mental state.
    • Neither gorillas nor chimpanzees have a VEN brain cell organized in clusters like those of humans and bonobos.
    • The only other animals with some form of VEN cells are whales, dolphins, and elephants, all animals with large brains and highly evolved social awareness, including empathy.
  • Pygmy chimpanzees show few individual differences in their blood groups (unlike P. troglodytesand humans).
    • Common chimps are either group A or O, and the A antigen of their red cells differs from those in human red cells.
    • Blood group studies show many differences between bonobos and common chimpanzees, enough that some researchers have suggested they should be in a separate genus. (Socha 1984)
  • Humans and chimpanzees share at least 98.5% of their DNA.
    • Great apes have 24 pairs of chromosomes
    • Humans have 23 pairs (18 of the 23 pairs are virtually identical)

Physical Commonalities

Bonobo

Bonobos are sometimes confused for chimpanzees, though their facial features, head shape, and long legs for a more upright posture make them quite different.

In terms of the "social parts of their brain," bonobos and humans are most similar among the great apes.

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Boesch (2002)
Cramer & Zihlman (1978)
Groves (1989)
Hakeem et al. (2009)
Myers & Thompson (2002)
Socha (1984)
de Waal (2001)
Zihlmann (1984, 1996)

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