Fissions of human communities are monumental occasions with consequences for cultural and genetic variation and divergence through time by means of serial founder effects. An ethnographic review shows that most human group fissions are fueled primarily by internal political conflict and secondarily by resource scarcity. As found for other social animals, human fissions lead to subgroups that have higher levels of relatedness as compared with the original community because of kin-biased assortment known as the lineal effect. Fission processes that increase the average relatedness of subgroups are important because relatedness governs how strongly kin/group selection favors social behaviors such as warfare, peacekeeping, and other forms of collection action. However, random individual assortment is not an appropriate null model for evaluating lineage assortment because nuclear families and extended households are expected to remain together, which in and of itself forces higher relatedness in smaller subgroups. We develop a lineage assortment index where low values represent subgroups with coefficients of relatedness near those expected if nuclear and extended households had chosen to associate into random groupings. Two fissions of Ache villages (Paraguay) are examples of this type of fission with a low lineage assortment index not significantly different from zero as evaluated with controlled simulations. On the other extreme, a lineage assortment index near unity represents a lineal fission that maximizes the relatedness of subgroups such as the perfect split of a lineage into sublineages. A fission of Piaroa (Venezuela) fits this scenario. While previous discussions of fission have emphasized similarities among human studies and even other social mammals, we highlight the full range of potential kin bias in the formation of new communities.
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Alexander, R. D. (1990). How humans evolved: Reflections on the uniquely unique species. Museum of Zoology (Special Publication No. 1). Ann Arbor: University of Michigan.
Altmann, J., Hausfater, G., & Atmann, S. A. (1985). Demography of Amboseli baboons. American Journal of Primatology, 8, 113–125.
Alvard, M. (2009). Kinship and cooperation. Human Nature, 20, 394–416.
Archie, E. A., Moss, C. J., & Alberts, S. C. (2006). The ties that bind: genetic relatedness predicts the fission and fusion of social groups in wild African elephants. Proceedings of the Royal Society of London. Series B: Biological Sciences, 273, 513–522.
Århem, K. (1981). Makuna social organization: A study in descent, alliance, and the formation of corporate groups in the north-western Amazon. Stockholm: Almqvist & Wiksell.
Carneiro, R. (1987). Village splitting as a function of population size. In L. Donald (Ed.), Themes in ethnology and culture history. Meerut: Archana Publications.
Cavalli-Sforza, L. L., Piazza, A., Menozzi, P., & Mountain, J. (1988). Reconstruction of human evolution: bringing together genetic, archaeological, and linguistic data. Proceedings of the National Academy of Sciences of the United States of America, 85, 6002–6006.
Chagnon, N. A. (1975). Genealogy, solidarity, and relatedness: limits to local group size and patterns of fissioning in an expanding population. Yearbook of Physical Anthropology, 19, 95–110.
Chagnon, N. A. (1976). Fission in an Amazonian tribe. New York Academy of Sciences, 16(1), 14–18.
Chagnon, N. A. (1979). Mate competition, favoring close kin, and village fissioning among the Yanomamö Indians. In N. A. Chagnon & W. A. Irons (Eds.), Evolutionary biology and human behavior. North Scituate: Duxbury Press.
Chagnon, N. A., & Bugos, P. E. (1979). Kin selection and conflict: An analysis of a Yanomamo ax fight. In N. A. Chagnon & W. A. Irons (Eds.), Evolutionary biology and human behavior (pp. 213–288). North Scituate: Duxbury Press.
Chapais, B. (2008). Primeval kinship: How pair bonding gave birth to human society. Cambridge: Harvard University Press.
Chepko-Sade, B. D., & Olivier, T. J. (1979). Coefficient of genetic relationship and the probability of intragenealogical fission in Macaca mulatta. Behavioral Ecology and Sociobiology, 5(3), 263–278.
Dumont, J.-P. (1978). The headman and I: Ambiguity and ambivalence in the fieldworking experience. Austin: University of Texas Press.
Early, J. D., & Peters, J. F. (2000). The Xilixana Yanomami of the Amazon: History, social structure, and population dynamics. Gainesville: University Press of Florida.
Eggan, F. (1950). Social organization of the Western Pueblos. Chicago: University of Chicago Press.
Evans-Pritchard, E. E. (1940). The Nuer: A description of the modes of livelihood and political institutions of a Nilotic people. Oxford: Clarendon.
Fix, A. G. (1975). Fission-fusion and lineal effect: aspects of the population structure of the Semai Senoi of Malaysia. American Journal of Physical Anthropology, 43, 295–302.
Fix, A. G. (1999). Migration and colonization in human microevolution. Cambridge: Cambridge University Press.
Fix, A. G. (2004). Kin-structured migration: causes and consequences. American Journal of Human Biology, 16, 387–394.
Freedman, D. G. (1984). Village fissioning, human diversity, and ethnocentrism. Political Psychology, 5(4), 629–634.
Goodenough, W. H. (1951). Property, kin, and community on Truk. New Haven: Yale University Publications.
Hamilton, W. D. (1964). The genetical evolution of social behavior, parts I and II. Journal of Theoretical Biology, 7, 1–52.
Hill, K. R., & Hurtado, A. M. (1996). Ache life history: The ecology and demography of a foraging people. New York: Aldine de Gruyter.
Hill, K. R., Walker, R. S., Bozicevic, M., Eder, J., Headland, T., et al. (2011). Co-residence patterns in hunter-gatherer societies show unique human social structure. Science, 331, 1286–1289.
Hoogland, J. L. (1995). The black-tailed prairie dog: Social life of a burrowing mammal. Chicago: University of Chicago Press.
Hunley, K. L., Spence, J. E., & Merriwether, D. A. (2008). The impact of group fissions on genetic structure in native South America and implications for human evolution. American Journal of Physical Anthropology, 135, 195–205.
Kaplan, J. O. (1975). The Piaroa: A people of the Orinoco Basin. Oxford: Clarendon.
Keesing, R. M. (1978). Elota’s story: The life and times of a Solomon Islands big man. New York: Henry Holt & Company.
Kelly, R. L. (2013). The lifeways of hunter-gatherers: The foraging spectrum (2nd ed.). Cambridge: Cambridge University Press.
Levy, J. (1992). Orayvi revisited: social stratification in an “egalitarian” society. Santa Fe: School of American Research Press.
Lewis, M. P., Simons, G. F., & Fennig, C. D. (Eds) (2013). Ethnologue: Languages of the world, 17th edition. Dallas, Texas: SIL International. Online version: http://www.ethnologue.com.
Marlowe, F. W. (2005). Hunter-gatherers and human evolution. Evolutionary Anthropology, 14, 54–67.
Matta, R. (1970). A divided world: Social structure of the Apinayé. PhD dissertation. Harvard University.
Maybury-Lewis, D. H. P. (1967). Akwa-Shavante society. Oxford: Clarendon.
Melatti, J. C. (1970). O sistema social Craô. PhD dissertation. Sao Paulo: Universidade de Sao Paulo.
Melnick, D. J. (1987). The genetic consequences of primate social organization: a review of macaques, baboons and vervet monkeys. Genetics, 73, 117–135.
Melnick, D. J., & Kidd, K. K. (1983). The genetic consequences of social group fission in a wild population of rhesus monkeys (Macaca mulatta). Behavioral Ecology and Sociobiology, 12, 229–236.
Metheny, J. D., Kalcounis-Ruepell, M. C., Bondo, K. J., & Brigham, R. M. (2008). A genetic analysis of group movement in an isolated population of tree-roosting bats. Proceedings of the Royal Society B, 275(1648), 2265–2272.
Neel, J. V. (1967). The genetic structure of primitive human populations. Journal of Human Genetics, 12, 1–16.
Neel, J. V., & Salzano, F. M. (1966). Further studies on the Xavante Indians: some hypotheses-generalizations resulting from these studies. American Journal of Human Genetics, 19(4), 554–574.
Nsubuga, A. M., Robbins, M. M., Boesch, C., & Vigilant, L. (2008). Patterns of paternity and group fission in wild multimale mountain gorilla groups. American Journal of Physical Anthropology, 135, 263–274.
O’Leary, T. J., Levinson, D., Hays, T. E., Hockings, P., Bennett, L. A., et al. (Eds.). (1994). Encyclopedia of world cultures. New York: Hall Publishing.
Oliver, D. (1955). A Solomon Islands society. Cambridge: Harvard University Press.
Olsen, C. L. (1976) The demography of new colony formation in a human isolate: An analysis and history. PhD dissertation, University of Michigan.
Olsen, C. L. (1987). The demography of colony fission from 1878–1970 among the Hutterites of North America. American Anthropologist, 89, 823–837.
Rappaport, R. A. (1968). Pigs for the ancestors: Ritual in the ecology of a New Guinea people. New Haven: Yale University Press.
Rodseth, L., Wrangham, R. W., Harrigan, A. M., & Smuts, B. B. (1991). The human community as a primate society. Current Anthropology, 32(3), 221–254.
Sahlins, M. D. (1961). The segmentary lineage: an organization of predatory expansion. American Anthropologist, 63(2), 322–345.
Silva, M. F. (2009). Romance de primas e primos: Uma etnografia do parentesco Waimiri-Atroari. Manaus: Valer Editora.
Smouse, P. E., Vitzthum, V. J., & Neel, J. V. (1981). The impact of random and lineal fission on the genetic divergence of small human groups: a case study among the Yanomama. Genetics, 98, 179–197.
Templeton, A. R. (1980). The theory of speciation via the founder principle. Genetics, 94, 1011–1038.
Titiev, M. (1972). The Hopi Indians of Old Oraibi: Change and continuity. Ann Arbor: University of Michigan Press.
Turnbull, C. M. (1965) The Mbuti Pygmies: an ethnographic survey. Anthropological papers of the American Museum of Natural History, 50, part 3. New York: American Museum of Natural History.
Turner, V. W. (1957). Schism and continuity in an African society. Manchester: Manchester University Press.
Van Horn, R. C., Buchan, J. C., Altmann, J., & Alberts, S. C. (2007). Divided destinies: group choice by female savannah baboons during social group fission. Behavioral Ecology and Sociobiology, 61, 1823–1837.
Verswijver, G. (1992). The club-fighters of the Amazon: Warfare among the Kaiapo Indians of Central Brazil. Gent: Rijksuniversiteit Te Gent.
Waterman, J. M. (2002). Delayed maturity, group fission and the limits of group size in female Cape ground squirrels (Xerus inauris: Sciuridae). Journal of Zoology, 256, 113–120.
Whiteley, P. M. (1988). Deliberate acts: Changing Hopi culture through the Oraibi split. Tucson: University of Arizona Press.
Whiteley, P. M. (2008). The Orayvi split: A Hopi transformation. Anthropological Papers of the American Museum of Natural History. Number 87. New York: American Museum of Natural History.
Wright, S. (1922). Coefficients of inbreeding and relationship. American Naturalist, 56, 330–338.
This paper benefited from help and conversations with Peter Whiteley, Greg Blomquist, Rob Boyd, Craig Palmer, and Stephen Beckerman. Financial support was provided by a National Geographic Society Research and Exploration grant (#9165-12).
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Walker, R.S., Hill, K.R. Causes, Consequences, and Kin Bias of Human Group Fissions. Hum Nat 25, 465–475 (2014). https://doi.org/10.1007/s12110-014-9209-0
- Group splits
- Lineal fissions
- Human kinship
- Genealogical relatedness
- Cross-cultural comparison