Some of the debates over the evolution of altruism and social groups can be tackled empirically, and criteria have been offered to decide between competing selection processes that might underlie the evolution of sociality. However, the typical model considers one selection process to be the main cause of the evolution of cooperation and cooperative groups. I argue, however, that at least in some cases, the evolution of cooperative groups can be better explained as the outcome of several selection processes, whether concurrent or sequential, rather than a single unifying process. Several examples from social spiders illustrate that selection processes cannot be reduced to particular instances of one overall process. I argue that seeking a unifying selection process for the evolution of altruism can reduce research productivity, generate misleading expectations and lead to false conclusions. On the other hand, looking at a combination of selection processes leads to new insights which are particularly relevant for the study of evolutionary transitions.
Axelrod, R. and Hamilton, W. D. (1981): The evolution of cooperation. Science211:1390-1396.
'The evolution of cooperation ' () 211 Science : 1390 -1396 .
Boyd, R. and Richerson, P. J. (1989): The evolution of indirect reciprocity. Social Networks11:213-236.
'The evolution of indirect reciprocity ' () 11 Social Networks : 213 -236 .
Crozier, R. H. and Pamilo, P. (1996): Evolution of Social Insect Colonies - Sex Allocation and Kin Selection. Oxford University Press, Oxford.
Evolution of Social Insect Colonies - Sex Allocation and Kin Selection , ().
Lloyd, E. A. (1988): The Structure and Confirmation of Evolutionary Theory. (second ed.). Princeton University Press, Princeton, 1994.
The Structure and Confirmation of Evolutionary Theory , ().
Zahavi, A. and Zahavi, A. (1997): The Handicap Principle: A Missing Piece of Darwin's Puzzle. Oxford University Press, Oxford.
The Handicap Principle: A Missing Piece of Darwin's Puzzle , ().
Maynard Smith, J. (1987a): How to model evolution. In Dupré, J. (ed.): The Latest on the Best: Essays on Evolution and Optimality. M.I.T. Press, Cambridge, Mass.
The Latest on the Best: Essays on Evolution and Optimality , ().
Maynard Smith, J. (1987b): Reply to Sober. In Dupré, J. (ed.): The Latest on the Best: Essays on Evolution and Optimality. M.I.T. Press, Cambridge, Mass.
The Latest on the Best: Essays on Evolution and Optimality , ().
Maynard Smith, J. (1999): The origin of altruism. Nature393:639-640.
'The origin of altruism ' () 393 Nature : 639 -640 .
Mitman, G. (1992): The State of Nature. University of Chicago Press, Chicago.
The State of Nature , ().
Mayr, E. (1990): Myxoma and group selection. Biologishes Zentralblatt.109:453-457.
'Myxoma and group selection ' () 109 Biologishes Zentralblatt. : 453 -457 .
Michod, R. E. (1999): Darwinian Dynamics - Evolutionary Transitions in Fitness and Individuality. Princeton University Press, Princeton, N. J.
Darwinian Dynamics - Evolutionary Transitions in Fitness and Individuality , ().
Maynard Smith, J. and Szathmáry, E. (1995): The Major Transitions in Evolution. W. H. Freeman, Oxford.
The Major Transitions in Evolution , ().
Nowak, M. A. and Sigmund, K. (1998): Evolution of indirect reciprocity by image scoring. Nature393:573-576.
'Evolution of indirect reciprocity by image scoring ' () 393 Nature : 573 -576 .
Wade, M. J. (1977): An experimental study of group selection. Evolution31:134-153.
'An experimental study of group selection ' () 31 Evolution : 134 -153 .
Wade, M. J. (1978): A critical review of the models of group selection. Q. Rev. Biol.53:101-114.
'A critical review of the models of group selection ' () 53 Q. Rev. Biol. : 101 -114 .
Wade, M. J. (1980): An experimental study of kin selection. Evolution34:844-855.
'An experimental study of kin selection ' () 34 Evolution : 844 -855 .
Wilson, D. S. and Sober, E. (1994): Reintroducing group selection to the human behavioral sciences. Behav. Brain Sci.17:585-654.
'Reintroducing group selection to the human behavioral sciences ' () 17 Behav. Brain Sci. : 585 -654 .
Alexander, R. D. (1974): The evolution of social behavior. Ann. Rev. Ecol. Systs.5:325-383.
'The evolution of social behavior ' () 5 Ann. Rev. Ecol. Systs. : 325 -383 .
Alexander, R. D., Nonnan, K. M. and Crespi, B. J. (1991): The evolution of eusociality. In Sherman, P. W., Jarvis, J. U. M. and Alexander, R. D. (eds): The Biology of the Naked Mole-Rat. Princeton University Press, Princeton.
The Biology of the Naked Mole-Rat , ().
Avilés, L. (1993): Interdemic selection and the sex ratio: A social spider perspective. Amer. Nat.142:320-345.
'Interdemic selection and the sex ratio: A social spider perspective ' () 142 Amer. Nat. : 320 -345 .
Avilés, L. (1997): Causes and consequences of cooperation and permanent-sociality in spiders. In Choe, J. C. and Crespi, B. J. (eds): The Evolution of Social Behavior in Insects and Arachnids. Cambridge University Press, Cambridge.
The Evolution of Social Behavior in Insects and Arachnids , ().
Avital, E. and Jablonka, E. (2000): Animal Traditions. Cambridge University Press, Cambridge.
Animal Traditions , ().
Boyd, R. and Richerson, P. J. (1992): Punishment allows the evolution of cooperation (or anything else) in sizable groups. Ethology and Sociobiology13:171-195.
'Punishment allows the evolution of cooperation (or anything else) in sizable groups ' () 13 Ethology and Sociobiology : 171 -195 .
Brandon, R. N. (1990): Adaptation and Environment. Princeton University Press, Princeton, N. J.
Adaptation and Environment , ().
Cangialosi, K. (1990): Social spider defense against klepto-parasitism. Behav. Ecol. Soc.27:49-54.
'Social spider defense against klepto-parasitism ' () 27 Behav. Ecol. Soc. : 49 -54 .
Coddington, J. A. and Levi, H. E. (1991): Systematics and evolution of spiders. Annu. Rev. Ecol. Syst.22:265-292.
'Systematics and evolution of spiders ' () 22 Annu. Rev. Ecol. Syst. : 265 -292 .
Colwell, R. K. (1981): Group selection is implicated in the evolution of female-biased sex ratios. Nature290:401-404.
'Group selection is implicated in the evolution of female-biased sex ratios ' () 290 Nature : 401 -404 .
Costa, J. T. and Fitzgerald, T. D. (1996): Developments in social terminology: semantic battles in a conceptual war. Trends Ecol. Evolut.11:285-289, 472-473.
'Developments in social terminology: semantic battles in a conceptual war ' () 11 Trends Ecol. Evolut. : 285 -289, 472-473 .
Craig, D. M. (1982): Group selection versus individual selection: An experimental analysis. Evolution36:271-282.
'Group selection versus individual selection: An experimental analysis ' () 36 Evolution : 271 -282 .
Crespi, B. J. and Choe, J. C. (1997): Explanation and evolution of social systems. In Choe, J. C. and Crespi, B. J. (eds): The Evolution of Social Behavior in Insects and Arachnids. Cambridge University Press, Cambridge.
The Evolution of Social Behavior in Insects and Arachnids , ().
Crow, J. F. and Aoki, K. (1982): Group selection for a poly-genic behavioral trait: a differential proliferation model. Proc. Natl. Acad. Sci.79:2628-2631.
'Group selection for a poly-genic behavioral trait: a differential proliferation model ' () 79 Proc. Natl. Acad. Sci. : 2628 -2631 .
Danforth, B. N. and Eickwort, G. C. (1997): The evolution of social behavior in the augochlorine sweat bees (Hymen-optera: Halictidae) based on a phylogenetic analysis of the genera. In Choe, J. C. and Crespi, B. J (eds): The Evolution of Social Behavior in Insects and Arachnids. Cambridge University Press, Cambridge.
The Evolution of Social Behavior in Insects and Arachnids , ().
Darwin, C. (1859): The Origin of Species By Means of Natural Selection. (The Modern Library, New York, 1998).
The Origin of Species By Means of Natural Selection , ().
Dawkins, R. (1976): The Selfish Gene. Oxford University Press, Oxford.
The Selfish Gene , ().
Dawkins, R. (1982): The Extended Phenotype. Oxford University Press, Oxford.
The Extended Phenotype , ().
Dugatkin, L. A. (1997): Cooperation among Animals. Oxford University Press, Oxford.
Cooperation among Animals , ().
Dugatkin, L. A. and Mesterton-Gibbons, M. (1996): Cooperation among unrelated individuals: reciprocal altruism, by-product mutualism, and group selection in fishes. Biosystems37:19-30.
'Cooperation among unrelated individuals: reciprocal altruism, by-product mutualism, and group selection in fishes ' () 37 Biosystems : 19 -30 .
Evans, T. A. (1997): Kin recognition in a social spider. Proc. R. Soc. Lond. B266:287-292.
'Kin recognition in a social spider ' () 266 Proc. R. Soc. Lond. B : 287 -292 .
Evans, T. A. (1998): Factors influencing the evolution of social behaviour in Australian crab spiders (Araneae: Thomisidae). Biol. J. Linnean Soc.63:205-219.
'Factors influencing the evolution of social behaviour in Australian crab spiders (Araneae: Thomisidae) ' () 63 Biol. J. Linnean Soc. : 205 -219 .
Frank, S. A. (1987): Demography and sex ratio in social spiders. Evolution41:1267-1281.
'Demography and sex ratio in social spiders ' () 41 Evolution : 1267 -1281 .
Frank, S. A. (1998): Foundations of Social Evolution. Princeton University Press, Princeton, N. J.
Foundations of Social Evolution , ().
Goodnight, C. J. and Stevens, L. (1992): Contextual analysis of models of group selection, soft selection, hard selection, and the evolution of altruism. Amer. Nat.140:734-761.
'Contextual analysis of models of group selection, soft selection, hard selection, and the evolution of altruism ' () 140 Amer. Nat. : 734 -761 .
Goodnight, C. J. and Stevens, L. (1997): Experimental studies of group selection: What do they tell us about group selection in nature? Amer. Nat.150:s59-s79.
'Experimental studies of group selection: What do they tell us about group selection in nature? ' () 150 Amer. Nat. : s59 -s79 .
Gould, S. J. and Lloyd, E. A. (1999): Individuality and adaptation across levels of selection: how shall we name and generalize the unit of Darwinism? Proc. Natl. Acad. Sci.96:11904-11909.
'Individuality and adaptation across levels of selection: how shall we name and generalize the unit of Darwinism? ' () 96 Proc. Natl. Acad. Sci. : 11904 -11909 .
Griesemer, J. R. (1999): Materials for the study of evolutionary transition. Biol. Phil.14:127-142.
'Materials for the study of evolutionary transition ' () 14 Biol. Phil. : 127 -142 .
Griesemer, J. R. (2000a): The units of evolutionary transtion. Selection1:67-80.
'The units of evolutionary transtion ' () 1 Selection : 67 -80 .
Griesemer, J. R. and Wade, M. J. (2000): Population herita-bility: extending punnett square concepts to evolution at the metapopulation level. Biol. Phil.15:1-17.
'Population herita-bility: extending punnett square concepts to evolution at the metapopulation level ' () 15 Biol. Phil. : 1 -17 .
Hamilton, W. D. (1964a): The genetical evolution of social behavior I. J. Theor. Biol.7:1-16.
'The genetical evolution of social behavior I ' () 7 J. Theor. Biol. : 1 -16 .
Hamilton, W. D. (1964b): The genetical evolution of social behavior II. J. Theor. Biol.7:17-52.
'The genetical evolution of social behavior II ' () 7 J. Theor. Biol. : 17 -52 .
Hamilton, W. D. (1971): Geometry of the selfish herd. J. Theor. Biol.31:295-311.
'Geometry of the selfish herd ' () 31 J. Theor. Biol. : 295 -311 .
Hamilton, W. D. (1975): Innate social aptitudes of man: an approach from evolutionary genetics. In Fox, R. (ed.): Biosocial Anthropology. Halsted Press, New York.
Biosocial Anthropology , ().
Jarvis, J. U. M. and Bennett, N. C. (1993): Eusociality has evolved independently in two genera of bathyergid mole-rats - but occurs in no other subterranean mammal. Behav. Ecol. Soc.33:253-260.
'Eusociality has evolved independently in two genera of bathyergid mole-rats - but occurs in no other subterranean mammal ' () 33 Behav. Ecol. Soc. : 253 -260 .
Keller, L. and Reeve, K. H. (1994): Partitioning of reproduction in animal societies. Trends Ecol. Evolut.9:98-103.
'Partitioning of reproduction in animal societies ' () 9 Trends Ecol. Evolut. : 98 -103 .
Kukuk, P. and Sage, G. (1994): Reproductivity and related-ness in a communal Halictine bee Lasioglossum (Chilalictus) hemichalceum. Insectes Sociaux41:443-455.
'Reproductivity and related-ness in a communal Halictine bee Lasioglossum (Chilalictus) hemichalceum ' () 41 Insectes Sociaux : 443 -455 .
Laporte, J. (2001): Selection for handicap. Biol. Phil.16:239-249.
'Selection for handicap ' () 16 Biol. Phil. : 239 -249 .
Lewontin, R. C. (1970): The unit of selection. Annu. Rev. Ecol. Syst.1:1-18.
'The unit of selection ' () 1 Annu. Rev. Ecol. Syst. : 1 -18 .
Lloyd, E. A. (1992): Unit of selection. In Keller, E. F. and Lloyd, E. A. (eds): Keywords in Evolutionary Biology. Harvard University Press, Cambridge, Mass.
Keywords in Evolutionary Biology , ().
Lubin, Y. (1974): Adaptive advantages and the evolutin of colony formation in Cyrtophora (Araneae: Araneidae). Zool. J. Linnean Soc.54:321-339.
'Adaptive advantages and the evolutin of colony formation in Cyrtophora (Araneae: Araneidae) ' () 54 Zool. J. Linnean Soc. : 321 -339 .
Lubin, Y. (1980): Population studies of two colonial orb-weaving spiders. Zool. J. Lin. Soc.70:265-287.
'Population studies of two colonial orb-weaving spiders ' () 70 Zool. J. Lin. Soc. : 265 -287 .
Lubin, Y. (1995): Is there division of labour in the social spider Achaearanea wau (Theridiidae)? Anim. Behav.49: 1315-1323.
'Is there division of labour in the social spider Achaearanea wau (Theridiidae)? ' () 49 Anim. Behav. : 1315 -1323 .
Maynard Smith, J. (1964): Group selection and kin selection. Nature201:1145-1147.
'Group selection and kin selection ' () 201 Nature : 1145 -1147 .
Pasquet, A., Trabalon, M. Bagnères, A. G. and Lebor-gne, R. (1997): Does group closure exist in the social spider Anelosimus eximius? Behavioral and chemical approach. Insectes sociaux44:159-169.
'Does group closure exist in the social spider Anelosimus eximius? Behavioral and chemical approach ' () 44 Insectes sociaux : 159 -169 .
Price, G. R. (1970): Selection and covariance. Nature227:520-521.
'Selection and covariance ' () 227 Nature : 520 -521 .
Reeve, H. K. and Keller, L. (2001): Tests of reproductive skew models in social insects. Annu. Rev. Entomol.46:347-385.
'Tests of reproductive skew models in social insects ' () 46 Annu. Rev. Entomol. : 347 -385 .
Reeve, H. K. and Sherman, P. W. (1996): The eusociality continuum revisited. Trends Ecol. Evolut.11:472.
'The eusociality continuum revisited ' () 11 Trends Ecol. Evolut. : 472 .
Griesemer, J. R. (2000b): Development, culture, and the units of inheritance. Phil. Sci.67:s348-s368.
'Development, culture, and the units of inheritance ' () 67 Phil. Sci. : s348 -s368 .
Smith, D. R. and Hagen, M. R. (1996): Population structure and interdemic selection in the cooperative spider Anelosimus eximius. J. Evol. Biol.9:589-608.
'Population structure and interdemic selection in the cooperative spider Anelosimus eximius ' () 9 J. Evol. Biol. : 589 -608 .
Sober, E. (1993): Philosophy of Biology. Oxford University Press, Oxford.
Philosophy of Biology , ().
Sober, E. and Wilson, D. S. (1994): A critical review of philosophical work on the units of selection problem. Phil. Sci.61:534-555.
'A critical review of philosophical work on the units of selection problem ' () 61 Phil. Sci. : 534 -555 .
Sober, E. and Wilson, D. S. (1998): Unto Others. Harvard University Press, Cambridge, Mass.
Unto Others , ().
Rowell, D. M. and Avilés, L. (1995): Sociality in a bark dwelling huntsman spider from Australia, Delena cancerides Walckenaer (Araneae: Sparassidae). Insectes Sociaux42:287-302.
'Sociality in a bark dwelling huntsman spider from Australia, Delena cancerides Walckenaer (Araneae: Sparassidae) ' () 42 Insectes Sociaux : 287 -302 .
Sherman, P. W., Jarvis, J. U. M., Alexander, R. D. (1991): The Biology of the Naked Mole-Rat. Princeton University Press, Princeton.
The Biology of the Naked Mole-Rat , ().
Smith, D. R. (1985): Habitat use by colonies of Philoponella republicana (Araneae: Uloboridae). J. Arachnology13: 363-373.
'Habitat use by colonies of Philoponella republicana (Araneae: Uloboridae) ' () 13 J. Arachnology : 363 -373 .
Jablonka, E. and Lamb, M. J. (1995): Epigenetic Inheritance and Evolution: The Lamarckian Dimension. Oxford University Press, Oxford.
Epigenetic Inheritance and Evolution: The Lamarckian Dimension , ().
Jablonka, E. (1994): "Inheritance systems and the evolution of new levels of individuality". J. Theor. Biol.170:301-309.
'"Inheritance systems and the evolution of new levels of individuality" ' () 170 J. Theor. Biol. : 301 -309 .
Hull, D. (1994): Taking vehicles seriously. Behav. Brain Sci.17:627-628.
'Taking vehicles seriously ' () 17 Behav. Brain Sci. : 627 -628 .
Heisler, I. L. and Damuth, J. (1987): A method for analyzing selection in hierarchically structured populations. Amer. Nat.130:582-602.
'A method for analyzing selection in hierarchically structured populations ' () 130 Amer. Nat. : 582 -602 .
Hull, D. (1980): Individuality and selection. Ann. Rev. Ecol. Syst.11:311-332.
'Individuality and selection ' () 11 Ann. Rev. Ecol. Syst. : 311 -332 .
Spinks, A. C., Jarvis, J. U. M. and Bennett, N. C. (2000): Comparative patterns of philopatry and dispersal in two common mole-rat populations: Implications for the evolution of mole-rat sociality. J. Anim. Ecol.69:224-234.
'Comparative patterns of philopatry and dispersal in two common mole-rat populations: Implications for the evolution of mole-rat sociality ' () 69 J. Anim. Ecol. : 224 -234 .
Trivers, R. L. (1971): The evolution of altruism. Q. Rev. Biol.46:35-57.
'The evolution of altruism ' () 46 Q. Rev. Biol. : 35 -57 .
Uetz, G. W. and Hieber, C. S. (1997): Colonial web-building spiders: balancing the costs and benefits of group-living. In Choe, J. C. and Crespi, B. J. (eds): The Evolution of Social Behavior in Insects and Arachnids. Cambridge University Press, Cambridge.
The Evolution of Social Behavior in Insects and Arachnids , ().
Wade, M. J. (1976): Group selection among laboratory populations of Tribolium. Proc. Natl. Acad. Sci.73:4604-4607.
'Group selection among laboratory populations of Tribolium ' () 73 Proc. Natl. Acad. Sci. : 4604 -4607 .
Wade, M. J. and Goodnight, C. J. (1998): Perspective: the theories of Fisher and Wright in the context of metapopu-lations: when nature does many small experiments. Evolution52:1537-1553.
'Perspective: the theories of Fisher and Wright in the context of metapopu-lations: when nature does many small experiments ' () 52 Evolution : 1537 -1553 .
Wade, M. J. and Goodnight, C. J. (1991): Wright's shifting balance theory: An experimental study. Science253:1015-1018.
'Wright's shifting balance theory: An experimental study ' () 253 Science : 1015 -1018 .
Wade, M. J. and Griesemer, J. R. (1998): Population herita-bility: empirical studies of evolution in metapopulations. Amer.Nat.151:135-147.
'Population herita-bility: empirical studies of evolution in metapopulations ' () 151 Amer.Nat. : 135 -147 .
Wcislo, W. T. (1997): Are behavioral classifications blinders to studying natural variation?. In Choe, J. C. and Crespi, B. J. (eds): The Evolution of Social Behavior in Insects and Arachnids. Cambridge University Press, Cambridge.
The Evolution of Social Behavior in Insects and Arachnids , ().
Whitehouse, M. E. A. and Lubin, Y. (1999): Competitive foraging in the social spider Stegodyphus dumicola. Anim. Behav.58:677-688.
'Competitive foraging in the social spider Stegodyphus dumicola ' () 58 Anim. Behav. : 677 -688 .
Williams, G. C. (1966): Adaptation and Natural Selection. Princeton University Press, Princeton.
Adaptation and Natural Selection , ().
Wilson, D. S. (1975): A general theory of group selection. Proc. Natl. Acad. Sci.72:143-146.
'A general theory of group selection ' () 72 Proc. Natl. Acad. Sci. : 143 -146 .
Wilson, D. S. (1983): The group selection controversy: history and current status. Annu. Rev. Ecol. Syst.14:159-187.
'The group selection controversy: history and current status ' () 14 Annu. Rev. Ecol. Syst. : 159 -187 .
Wimsatt, W. C. (1980): Reductionistic research strategies and their biases in the units of selection controversy. In Nickles, T. (ed.): Scientific Discovery: Case Studies, Vol. 2. Reidel, Dordrecht, pp. 213-259.
Scientific Discovery: Case Studies , () 213 -259 .
Wright, S. (1945): Tempo and mode in evolution: a critical review. Ecology 26:415-419.
'Tempo and mode in evolution: a critical review ' () Ecology : 415 -419 .
Zahavi, A. (1975): Mate selection - a selection for a handicap. J. Theor. Biol.53:205-214.
'Mate selection - a selection for a handicap ' () 53 J. Theor. Biol. : 205 -214 .
Zahavi, A. (1995): Altruism as a handicap -the limitations of kin selection and reciprocity. J. Avian Biol.26:1-3.
'Altruism as a handicap -the limitations of kin selection and reciprocity ' () 26 J. Avian Biol. : 1 -3 .
Riechert, S. E. and Roeloffs, R. M. (1993): Evidence for and consequences of inbreeding in the cooperative spiders. In Thornhill, N. W. (ED.): The Natural History of In breeding and Outbreeding: Theoretical and Empirical Perspectives. University of Chicago Press, Chicago.
The Natural History of In breeding and Outbreeding: Theoretical and Empirical Perspectives , ().
Rissing, S. W., Pollock, G. B., Higgins, M. R., Hagen, R. H. and Smith, D. R. (1989): Foraging specialization without relatedness or dominance among co-founding ant queens. Nature338:420-422.
'Foraging specialization without relatedness or dominance among co-founding ant queens ' () 338 Nature : 420 -422 .
Furey, R. E. (1998): Two cooperatively social populations of the theridiid spider Anelosimus studiosus in a temperate region. Anim. Behav. 55:727-735.
'Two cooperatively social populations of the theridiid spider Anelosimus studiosus in a temperate region ' () 55 Anim. Behav. : 727 -735 .