Patriarchal Chimpanzees, Matriarchal Bonobos: Potential Ecological Causes of a Pan Dichotomy

  • Volker SommerEmail author
  • Jan Bauer
  • Andrew Fowler
  • Sylvia Ortmann
Part of the Developments in Primatology: Progress and Prospects book series (DIPR, volume 35)


Chimpanzees and bonobos, despite being closely related hominoid primates, differ in female gregariousness and dominance style. Violent male aggression is not atypical in chimpanzee societies and is vented against both other males and females in intra- as well as inter-group conflicts; relationships amongst females are rather weak. Bonobo societies, on the other hand, are female-centred; reports[Comp1] about inter-group conflict are rare to absent but there are numerous reports of blood-drawing injuries inflicted upon males by coalitions of females.

This dichotomy is of potential interest for the understanding of social dynamics in contemporary human societies, too, given that Pan and Homo shared a last ­common ancestor 5 – 6 million years ago. For example, political agendas to achieve a greater equality of the sexes might have to work against our natural inclinations, if the last common ancestor exhibited the patriarchal tendencies found in chimpanzees. Vice versa, if the last common ancestor possessed the matriarchal tendencies of bonobos, then patriarchal tendencies in contemporary human societies could be understood as rather recent cultural developments that can be more easily undone by counter-measures, i.e., changes in socio-economic dynamics.

Such assertions are not unproblematic, given millions of years of evolution. Nevertheless, a reconstruction of the ancestral roots of the behavioural suites of Homo and Pan will have to rely on a causal understanding of the different species psychologies of chimpanzees versus bonobos. These should in some ways be related to ecology. Both species have a mixed diet dominated by fruit with a similar composition. To test if their diet differs in availability and quality, we collected data on habitat phenology and analysed nutritional content of food plants and non-food plants from a community of bonobos in Salonga National Park, Democratic Republic of Congo, and a community of chimpanzees living in Gashaka Gumti National Park / Nigeria.

We found that chimpanzee diet is more diverse, whereas bonobos can rely on a few staple species for longer periods of time – which reflects the more seasonal climate at the chimpanzee site. Both species prefer fruit with elevated contents of water, sugar and fat, but chimpanzees have to cope with much higher levels of anti-feedants such as tannins. Moreover, only bonobos have access to a herb with low levels of fibre but high protein. In addition, chimpanzees invest more time and energy in the removal of seeds from fruit and in digestion. The costs of acquisition of high quality food are thus higher in chimpanzees than in bonobos. The greater constraints in terms of food availability and quality are reflected in greater levels of female-female competition as evidenced by consistently lower levels of gregariousness in chimpanzees measured through the size of nest groups.

Thus, local ecologies can modify social behaviours. However, support for the hypothesis that ecological differences are at the heart of the dichotomy of sociality in Pan is not unequivocal because of considerable intra-specific variability throughout the geographical range of bonobos and, in particular, chimpanzees with respect to social processes and fluctuating parameters of flora, fauna and climate. Accordingly, future studies will have to explore the extent of this flexibility and if and how it covaries with local ecologies.


Pan troglodytes Pan paniscus Matriarchy Food quality 


  1. Alm, U., Birgersson, B. & Leimar, O. (2000). The effect of food quality and relative abundance on food choice in fallow deer. Animal Behaviour 64: 439–445.CrossRefGoogle Scholar
  2. Altmann, S. A. (1998). Foraging for Survival. Chicago: The University of Chicago Press.Google Scholar
  3. Anderson, D. P., Nordheim, E. V., Boesch, C. & Moermond, T. C. (2002). Factors influencing fission-fusion grouping in chimpanzees in the Taï National Park, Cote d’Ivoire. In Boesch, C., Hohmann, G. & Marchant, L. F. (eds.), Behavioural Diversity in Chimpanzees and Bonobos. Cambridge: Cambridge University Press, pp. 90–101.CrossRefGoogle Scholar
  4. Badrian, N. L. & Malenky, R. K. (1984). Feeding ecology of Pan paniscus in the Lomako Forest, Zaire. In Susman, L. S. (ed.), The Pygmy Chimpanzee: Evolutionary Biology and Behavior. New York: Plenum Press, pp. 275–299.Google Scholar
  5. Bauer, J. (2006). Vergleichende Faecesuntersuchungen bei Pan paniscus, Pan troglodytes vellerosus und Pan troglodytes verus. Diplomarbeit, Humboldt-Universität Berlin / Germany.Google Scholar
  6. Belovsky, G. E. (1978). Diet optimization in a generalist herbivore: the moose. Theoretical Population Biology 14: 105–134.PubMedCrossRefGoogle Scholar
  7. Berkhoudt, K., Fruth, B. & Garber, P. A. (2005). Food Patch Choice of Bonobos (Pan paniscus) in Lui Kotal, the Democratic Republic of Congo. Poster presented at the American Association of Physical Anthropologists, April 6–9, 2005.Google Scholar
  8. Boesch, C. & Boesch-Achermann, H. (2000). The Chimpanzees of the Taï Forest. Behavioural Ecology and Evolution. Oxford: Oxford University Press.Google Scholar
  9. Boesch, C., Hohmann, G. & Marchant, L. F. (eds.) (2002). Behavioural Diversity in Chimpanzees and Bonobos. Cambridge: Cambridge University Press.Google Scholar
  10. Campbell, C. J., Fuentes, A., Mackinnon, K. C., Panger, M. & Bearder, S. K. (Hg.) (2007). Primates in Perspective. Oxford: Oxford University Press.Google Scholar
  11. Campos-Arceiz, A., Takatsuki, S. & Lhagvasuren, B. (2004). Food overlap between Mongolian gazelles and livestock in Omnogobi, southern Mongolia. Ecological Research 19: 455–460.CrossRefGoogle Scholar
  12. Carlo, T. A., Collazo, J. A. & Groom, M. J. (2003). Avian fruit preferences across a Puerto Rican forest landscape: pattern consistency and implications for seed removal. Oecologia 134: 119–31.PubMedCrossRefGoogle Scholar
  13. Chapman, C. A., White, F. J. & Wrangham, R. W. (1994). Party size in chimpanzees and bonobos: a reevaluation of theory based on two similarly forested sites. In Wrangham, R. W., McGrew, W. C., de Waal, F. B. M. & Heltne, P. G. (eds.), Chimpanzee Cultures. Cambridge: Harvard University Press, pp. 41–57.Google Scholar
  14. Clauss, M. & Lechner-Doll, M. (2001). Differences in selective reticulo-ruminal particle retention as a key factor in ruminant diversification. Oecologia 129: 321–27.Google Scholar
  15. Clauss, M. (2003). Tannins in the nutrition of wild animals: a review. In Fidgett, A., Clauss, M., Gansloser, U., Hatt, J. M. & Nijboer, J. (eds.), Zoo Animal Nutrition, Volume 2. Fürth: Filander Verlag, pp. 53–89.Google Scholar
  16. Clauss, M., Lechner-Doll, M. & Streich, W. J. (2002). Faecal particle size distribution in captive wild ruminants: an approach to the browser / grazer from the other end. Oecologia 131: 343–49.CrossRefGoogle Scholar
  17. Clauss, M., Lason, K., Gehrke, J., Lechner-Doll, M., Fickel, J., Grune, T. & Streich, W. J. (2003). Captive roe dee (Capreolus capreolus) select for low amounts of tannin acid but not quebracho: fluctuation of preferences and potential benefits. Comparative Biochemistry and Physiology B 136: 369–382.CrossRefGoogle Scholar
  18. Conklin-Brittain, N. L., Wrangham, R. W. & Hunt, K. D. (1998). Dietary response of chimpanzees and Cercopithecines to seasonal variation in fruit abundance. II. Macro-nutrients. International Journal of Primatology 19: 971–998.CrossRefGoogle Scholar
  19. Corlett, R. T. & Lucas, P. W. (1990). Alternative seed-handling strategies in primates: seed-spitting by long-tailed macaques (Macaca fascicularis). Oecologia 82: 166–171.CrossRefGoogle Scholar
  20. De Waal, F. B. M. & Lanting, F. 1997. Bonobo: The Forgotten Ape. Berkeley, Los Angeles: University of California Press.Google Scholar
  21. Dearing, M. D. & Schall, J. J. (1992). Testing models of diet assembly by the generalist herbivore lizard, Cnemidophorus murinus. Ecology 73: 845–867.CrossRefGoogle Scholar
  22. de Beauvoir, S. [1949] (1973). The Second Sex. New York: Vintage Books.Google Scholar
  23. Deblauwe, I. & Janssens, G. P. J. (2007). New insights in insect prey choice by chimpanzees and gorillas in southeast Cameroon: the role of nutritional value. American Journal of Physical Anthropology 135: 42–55.CrossRefGoogle Scholar
  24. Eller, C. (2000). The Myth of Matriarchal Prehistory. Why an Invented Past Won’t Give Women a Future. Boston: Beacon Press.Google Scholar
  25. Emlen, J. M. (1966). The role of time and energy in food preferences. The American Naturalist 100: 611–617.CrossRefGoogle Scholar
  26. Fjeldsa, J. & Lovett, J. C. (1997). Geographical patterns of old and young species in African forest biota: the significance of specific montane areas as evolutionary centres. Biodiversity and Conservation 6: 325–346.CrossRefGoogle Scholar
  27. Fowler, A. (2006). Socio-ecology of Nigerian Chimpanzees at Gashaka. PhD thesis, University of London.Google Scholar
  28. Fowler, A & Sommer, V. (2007). Subsistence technology in Nigerian chimpanzees. International Journal of Primatology 28: 997–1023.CrossRefGoogle Scholar
  29. Freeland, W. J. & Janzen, D. H. (1974). Strategies in herbivory by mammals: the role of plant secondary compounds. The American Naturalist 108: 269–289.CrossRefGoogle Scholar
  30. Fruth, B. (1995). Nests and Nest Groups in Wild Bonobos (Pan paniscus): Ecological and Behavioural Correlates. Aachen: Shaker.Google Scholar
  31. Fruth, B. & Hohmann, G. (1996). Nest building behaviour in the great apes: the great leap ­forward? In McGrew, W. C., Marchant, L. F. & Nishida, T. (eds.), Great Ape Societies. New York: Cambridge University Press, pp. 225–240.CrossRefGoogle Scholar
  32. Fruth, B. & Hohmann, G. (2006). Social grease for females? Same-sex genital contacts in wild bonobos. In Sommer, V. & Vasey, P. (eds.), Homosexual Behaviour in Animals: Evolutionary Perspectives. Cambridge: Cambridge University Press, pp. 294–315.Google Scholar
  33. Gerloff, U., Hartung, B., Fruth, B., Hohmann, G. & Tautz, D. (1999). Intracommunity relationships, dispersal pattern and paternity success in a wild living community of bonobos (Pan paniscus) determined from DNA analysis of faecal samples. Proceedings of the Royal Society of London, B 266: 1189–1195.CrossRefGoogle Scholar
  34. Goldberg, S. (1993). Why Men Rule. Chicago, Illinois: Open Court Publishing Company.Google Scholar
  35. Goodall, J. (1986). The Chimpanzees of Gombe: Patterns of Behaviour. Cambridge, MA: Harvard University Press.Google Scholar
  36. Harbourne, J. B. (1993). Introduction to Ecological Biochemistry. San Diego: Academic Press.Google Scholar
  37. Harcourt, A. H. & Stewart, K. J. (2007). Gorilla Society: Conflict, Compromise, and Cooperation Between the Sexes. Chicago: The University of Chicago Press.Google Scholar
  38. Hashimoto, C., Suzuki, S., Takenoshita, Y., Yamagiwa, J., Basabose, A. K. & Furuichi, T. (2004). How fruit abundance affects the chimpanzee party size: a comparison between four study sites. Primates 44: 77–81.Google Scholar
  39. Heltne, P. G. & Marquardt, L. A. (eds.) (1989). Understanding Chimpanzees. Cambridge, MA: Harvard University Press.Google Scholar
  40. Hemelrijk, C. K., Wantia, J. & Isler, K. (2008). Female dominance over males in primates: Self-organisation and sexual dimorphism. PLoS ONE 3: e2678.PubMedCrossRefGoogle Scholar
  41. Hladik, C. M. (1977). A comparative study of the feeding strategies of two sympatric species of leaf monkeys: Presbytis senex and Presbytis entellus. In Clutton-Brock, T. H. (ed.), Primate Ecology: Studies of Feeding and Ranging Behaviour in Lemurs, Monkeys and Apes. London: Academic Press, pp. 323–353.Google Scholar
  42. Hohmann, G. & Fruth, B. (1995). Loud calls in great apes: sex differences and social correlates. In Zimmermann, E., Newman, J. D. & Jürgens, U. (eds.), Current Topics in Primate Vocal Communication. New York: Plenum Press, pp. 161–184.Google Scholar
  43. Hohmann, G. & Fruth, B. (2003a). Lui Kotal – a new site for field research on bonobos in the Salonga National Park. Pan African News 10: 25–27.Google Scholar
  44. Hohmann, G. & Fruth, B. (2003b). Intra- and inter-sexual aggression by bonobos in the context of mating. Behaviour 140: 1389–1413.CrossRefGoogle Scholar
  45. Hohmann, G., Sommer, V. & Ortmann, S. (2007). What’s on the menue? Variation in nutritional ecology of bonobos and chimpanzees. Abstract. (Italy Conference).Google Scholar
  46. Hohmann, G., Fowler, A., Sommer, V. & Ortmann, S. (2006). Frugivory and gregariousness of Salonga bonobos and Gashaka chimpanzees: the abundance and nutritional quality of fruit. In Hohmann, G. (ed.), Feeding Ecology of Apes and Other Primates. Cambridge: Cambridge University Press, pp. 123–159.Google Scholar
  47. Hohmann, G. & Fruth, B. (2008). New records on prey capture and meat eating by bonobos at Lui Kotale, Salonga National Park, Democratic Republic of Congo. Folia Primatologica 79:103–110.Google Scholar
  48. Kano, T. (1992). The Last Ape: Pygmy Chimpanzee Behavior and Ecology. Stanford, CA: Stanford University Press.Google Scholar
  49. Krishnamani, R. & Mahaney, W. C. (2000). Geophagy among primates: adaptive significance and ecological consequences. Animal Behaviour 59: 899–915.PubMedCrossRefGoogle Scholar
  50. Kummer, H. (1971). Primate Societies. Chicago: Aldine.Google Scholar
  51. Lambert, J. E. (1998). Primate digestion: interactions among anatomy, physiology, and feeding ecology. Evolutionary Anthropology 7: 8–20.CrossRefGoogle Scholar
  52. Lambert, J. E. (2006). Primate nutritional ecology: feeding biology and diet at ecological and evolutionary scales. In Campbell, C., Fuentes, A., MacKinnon, K. C., Panger, M. & Bearder, S. (eds.), Primates in Perspective. New York, Oxford: Oxford University Press, pp. 482–495.Google Scholar
  53. Leigh, E. G. & Windsor, D. M. (1982). Forest production and regulation of primary consumers on Barro Colorado Island. In Stanley Rand, A., Windsor, D. M. & Leigh, E. G. (eds.), The Ecology of a Tropical Forest: Seasonal Rhythms and Long-term Changes. Washington: Smithsonian Institution Press, pp. 111–122.Google Scholar
  54. Leighton, M. (1993). Modeling dietary selectivity by Bornean orangutans: evidence for integration of multiple criteria in fruit selection. International Journal of Primatology 14: 257–313.CrossRefGoogle Scholar
  55. Lotz, C. N. & Nicolson, S. W. (1996). Sugar preference of a nectarivorous passerine bird, the lesser double-collared sunbird (Nectarinia chalybea). Functional Ecology 10: 360–365.CrossRefGoogle Scholar
  56. Makkar, H. P. S. & Becker, K. (1998). Do tannins in leaves of trees and shrubs from African and Himalayan regions differ in level and activity? Agroforestry Systems 40: 59–68.CrossRefGoogle Scholar
  57. Makkar, H. P. S., Bluemmel, M., Borowy, N. K. & Becker, K. (1993). Gravimetric determination of tannins and their correlations with chemical and protein precipitation methods. Journal of the Science of Food and Agriculture 61: 161–164.CrossRefGoogle Scholar
  58. Malenky, R. (1990). Ecological Factors Affecting Food Choice and Social Organization in Pan paniscus. PhD thesis, State University of New York.Google Scholar
  59. Malenky, R. K. & Stiles, E. W. (1991). Distribution of terrestrial herbaceous vegetation and its consumption by Pan paniscus in the Lomako Forest, Zaire. American Journal of Primatology 23: 153–169.CrossRefGoogle Scholar
  60. Matsumoto-Oda, A. & Hayashi, Y. (1999). Nutritional aspects of fruit choice by chimpanzees. Folia Primatologica 70: 154–162.CrossRefGoogle Scholar
  61. McGrew, W. C. (2004). The Cultured Chimpanzee: Reflections on Cultural Primatology. Cambridge: Cambridge University Press.CrossRefGoogle Scholar
  62. McGrew, W. C., Marchant, L. F. & Nishida, T. (eds.) (1996). Great Ape Societies. Cambridge: Cambridge University Press.Google Scholar
  63. McGrew, W. C., Marchant, L. F., Beuerlein, M. M., Vrancken, D., Fruth, B. & Hohmann, G. (2007). Prospects for bonobo insectivory: Lui Kotal, Democratic Republic of Congo. International Journal of Primatology 28: 1237–1252.CrossRefGoogle Scholar
  64. Miller, L. (ed.) (2002). Eat or be Eaten: Predator Sensitive Foraging Among Primates. Cambridge University Press, Cambridge.Google Scholar
  65. Milton, K. (1978). Behavioral adaptations to leaf-eating by the mantled howler monkey (Alouatta palliata). In Montgomery, G. G. (ed.), Ecology of Arboreal Folivores. Washington, D. C.: Smithsonian Press, pp. 535–549.Google Scholar
  66. Milton, K. (1981). Food choice and digestive strategies of two sympatric primate species. The American Naturalist 117: 476–495.CrossRefGoogle Scholar
  67. Milton, K. & McBee, R. H. (1983). Rates of fermentative digestion in the howler monkey (Alouatta palliate) (Primates: Cebidae). Comparative Biochemistry and Physiology 7: 4–29.Google Scholar
  68. Mitani, J. C., Watts, D. P. & Lwanga, J. S. (2002). Ecological and social correlates of chimpanzee party size and composition. In Boesch C., Hohmann, G. & Marchant L. F. (eds.), Behavioural Diversity in Chimpanzees and Bonobos. Cambridge: Cambridge University Press, pp. 102–111.CrossRefGoogle Scholar
  69. Morin, P. A., Moore, J. J., Chakraborty, R., Jin, L., Goodall, J. & Woodruff, D. (1994). Kin selection, social structure, gene flow, and the evolution of chimpanzees. Science 265: 1193–1201.PubMedCrossRefGoogle Scholar
  70. Mueller-Harvey, I. & McAllan, A. B. (1992). Tannins, their biochemistry and nutritional properties. Advances in Plant Cell Biochemistry and Biotechnology 1: 151–217.Google Scholar
  71. Nunn, C. L. & Altizer, S. (2006). Infectious Diseases in Primates: Behavior, Ecology and Evolution. (Oxford Series in Ecology & Evolution). Oxford: Oxford University Press.CrossRefGoogle Scholar
  72. Oates, J. F., Bergl, R. A. & Linder, J. M. (2004). Africa’s Gulf of Guinea Forests: Biodiversity Patterns and Conservation Priorities. (Advances in Applied Biodiversity Science 6). Washington, DC: Conservation International.Google Scholar
  73. Parish, A. R. (1994). Sex and food control in the “uncommon chimpanzee”: How bonobo females overcome a phylogenetic legacy of male dominance. Ethology and Sociobiology 15: 157–179.CrossRefGoogle Scholar
  74. Parish, A. R. (1996). Female relationships in bonobos (Pan paniscus): evidence for bonding, cooperation, and female dominance in a male-philopatric species. Human Nature 7: 61–96.Google Scholar
  75. Parish, A. R. & de Waal, F. (2000). The other “closest living relative”. How bonobos (Pan paniscus) challenge traditional assumptions about females, dominance, intra- and intersexual interactions, and hominid evolution. Annals of the New York Academy of Sciences 907: 97–113.PubMedCrossRefGoogle Scholar
  76. Parker, I. (2007). Swingers. Bonobos are celebrated as peace-loving, matriarchal, and sexually liberated. Are they? The New Yorker July 30: 48–61.Google Scholar
  77. Poppi, D., Norton, B., Minson, D. & Hendricksen, R. (1980). The validity of the critical size theory for particles leaving the rumen. Journal of Agricultural Science Camb. 94: 275–280.CrossRefGoogle Scholar
  78. Porter, L. J., Hrstich, L. N. & Chan, B. G. (1986). The conversion of procyanadins and prodelphinidins to cyanidin and delphinidin. Phytochemistry 25: 223–230.CrossRefGoogle Scholar
  79. Poulin, B., Wright, S. J., Lefebvrev, G. & Calderon, O. (1999). Interspecific synchrony and asynchrony in the fruiting phenologies of congeneric bird-dispersed plants in Panama. Journal of Tropical Ecology 15: 213–227.CrossRefGoogle Scholar
  80. Raubenheimer, D. & Simpson, S. J. (1997). Integrative models of nutrient balancing: application to insects and vertebrates. Nutritional Research Reviews 10: 151–179.CrossRefGoogle Scholar
  81. Remis, M. J. (2002). Food preferences among captive western gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes). International Journal of Primatology 23: 231–249.CrossRefGoogle Scholar
  82. Reynolds, V. (2005). The Chimpanzees of the Budongo Forest. Oxford: Oxford University Press.CrossRefGoogle Scholar
  83. Reynolds, V., Plumptre, A. J., Greenham, J. & Harborne, J. (1998). Condensed tannins and sugars in the diet of chimpanzees (Pan troglodytes schweinfurthii) in the Budongo Forest, Uganda. Oecologia 115: 331–336.CrossRefGoogle Scholar
  84. Robbins, M. M. (2007). Gorillas: Diversity in ecology and behavior. In Campbell, C. J., Fuentes, A., MacKinnon, K. C., Panger, M., Bearder, S. K. (eds.), Primates Perspective. New York: Oxford University Press, pp. 305–317.Google Scholar
  85. Rodman, P. S. (2002). Plants of the apes: is there a hominoid model for the origins of the hominoid diet? In Ungar, P. S. & Teaford, M. F. (eds.), Human Diet: Its Origin and Function. Westpoint: Bergin & Harvey, pp. 77–109.Google Scholar
  86. Rogers, M. E., Maisels, F., Williamson, E. A., Fernandez, M. & Tutin, C. E. G. (1990). Gorilla diet in the Lopé Reserve, Gabon: a nutritional analysis. Oecologia 84: 326–339.Google Scholar
  87. Saracco, J. F., Collazo, J. A. & Groom, M. J. (2004). How frugivores track resources? Insight from spatial analyses of bird foraging in a tropical forest. Oecologia 139: 235–45.PubMedCrossRefGoogle Scholar
  88. Schaefer, H. M., Schmidt, V. & Baierlein, F. (2003). Discrimination abilities for nutrients: which difference matters for choosy birds and why? Animal Behaviour 65: 531–541.CrossRefGoogle Scholar
  89. Schöning, C., Ellis, D., Fowler, A. & Sommer, V. (2007). Army ant prey availability and consumption by chimpanzees at Gashaka (Nigeria). Journal of Zoology 271: 125–133.CrossRefGoogle Scholar
  90. Sommer, V. (2000). The holy wars about infanticide. Which side are you on? And why? In van Schaik, C. & Janson, C. (eds.), Infanticide by Males and its Implications. Cambridge: Cambridge University Press, pp. 9–26.CrossRefGoogle Scholar
  91. Sommer, V. (2008). Welcher Affe steckt in uns? Bild der Wissenschaft 4: 18–25.Google Scholar
  92. Sommer, V., Adanu, J., Faucher, I. & Fowler, A. (2004). The Nigerian Chimpanzee (Pan troglodytes vellerosus) at Gashaka: Two years of habituation efforts. Folia Primatologica 75: 295–316.CrossRefGoogle Scholar
  93. Stanford, C. (1998). The social behavior of chimpanzees and bonobos: Empirical evidence and shifting assumptions. Current Anthropology 39: 399–420.CrossRefGoogle Scholar
  94. Susman, R. L. (Hg.) (1984). The Pygmy Chimpanzee: Evolutionary Biology and Behavior. New York: Plenum.Google Scholar
  95. Takemoto, H. (2003). Phytochemical determination for leaf food choice by wild chimpanzees in Guinea, Bossou. Journal of Chemical Ecology 29: 2551–2573.PubMedCrossRefGoogle Scholar
  96. Trivers, R. L. (1972). Parental investment and sexual selection. In Campbell, B. (Hg.) (ed.), Sexual Selection and The Descent of Man, 1871–1971. Illinois, Chicago : Aldine Press, pp. 136–179.Google Scholar
  97. Tutin, C. E. G. & Fernandez, M. (1993). Relationships between minimum temperature and fruit production in some tropical forest trees in Gabon. Journal of Tropical Ecology 9: 241–248.CrossRefGoogle Scholar
  98. van Schaik, C. P. (1989). The ecology of social relationships amongst female primates. In Standen, V. & Foley, R. A. (eds.), Comparative Socioecology. Oxford: Blackwell Scientific Publications. 195–218.Google Scholar
  99. van Soest, P. J. (1994). Nutritional Ecology of the Ruminant. Ithaca: Cornell University Press.Google Scholar
  100. Vervaecke, H., de Vries, H. & van Elsacker, L. (2000). Function and distribution of coalitions in captive bonobos (Pan paniscus). Primates 41: 249–265.CrossRefGoogle Scholar
  101. Vogel, C. (1999). Anthropologische Spuren. Zur Natur des Menschen. Ed. & introd. by Sommer, V.; Edition Universitas. Stuttgart: Hirzel.Google Scholar
  102. Vogel, C. & Sommer, V. (1994). Drum prüfe, wer sich ewig bindet. In Schiefenhövel, W., Vogel, C., Vollmer, G. (eds.), Vom Affen zum Halbgott. Stuttgart: Trias, pp. 13–42.Google Scholar
  103. White, F. J. & Wrangham, R. W. (1988). Food competition and patch size in the chimpanzee ­species Pan paniscus and Pan troglodytes. Behaviour 105: 148–164.CrossRefGoogle Scholar
  104. Witmer, M. C. (1998). Do seeds hinder digestive processing of fruit pulp? implications for plant / frugivore mutualisms. The Auk 115: 319–326.Google Scholar
  105. Witmer, M. C. & van Soest, P. J. (1998). Contrasting digestive strategies of fruit-eating birds. Functional Ecology 12: 728–741.CrossRefGoogle Scholar
  106. Wittig, R. & Boesch, C. (2003). The choice of post-conflict interactions in wild chimpanzees (Pan troglodytes). Behaviour 140: 1527–1559.CrossRefGoogle Scholar
  107. Wrangham, R. W. (1979). On the evolution of ape social systems. Social Science Information 18: 335–368.CrossRefGoogle Scholar
  108. Wrangham, R. W. (1980). An ecological model of female-bonded primate groups. Behaviour 75: 262–300.CrossRefGoogle Scholar
  109. Wrangham, R. W. (1986). Ecology and social evolution in two species of chimpanzees. In Rubenstein, D. I. & Wrangham, R. W. (eds.), Ecology and Social Evolution: Birds and Mammals. Princeton: Princeton University Press, pp. 352–378.Google Scholar
  110. Wrangham, R. & Peterson, D. (1996). Demonic Males. Apes and the Origins of Human Violence. London: Bloomsbury.Google Scholar
  111. Wrangham, R. W. & Waterman, P. G. (1983). Condensed tannins in fruits eaten by chimpanzees. Biotropica 15: 217-222.CrossRefGoogle Scholar
  112. Wrangham, R. W., Conklin-Brittain, N. L. & Hunt, K. D. (1998). Dietary response of chimpanzees and Cercopithecines to seasonal variation in fruit abundance. I. Anti-feedants. International Journal of Primatology 19: 949–970.CrossRefGoogle Scholar
  113. Wrangham, R. W., Chapman, C. A., Clark-Arcadi, A. P. & Isabirye-Basuta, G. (1996). Social ecology of Kanyawara chimpanzees: implications for understanding the costs of great ape groups. In McGrew, W. C., Marchant, L. F. & Nishida, T. (eds.), Great Ape Societies. New York: Cambridge University Press, pp. 45–57.CrossRefGoogle Scholar
  114. Wrangham, R. W., Conklin, N. L., Chapman, C. A. & Hunt, K. D. (1991). The significance of fibrous foods for Kibale Forest chimpanzees. Philosophical Transactions of the Royal Society of London, B 334: 171–178.CrossRefGoogle Scholar
  115. Wrangham, R. W., McGrew, W. C., de Waal, F. B. M. & Heltne, P. G. (eds.) (1994). Chimpanzee Cultures. Cambridge, MA: Harvard University Press.Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Volker Sommer
    • 1
    Email author
  • Jan Bauer
  • Andrew Fowler
  • Sylvia Ortmann
  1. 1.Department of AnthropologyUniversity College LondonLondonUK

Personalised recommendations