Milton, K. in Machiavellian Intelligence: Social Expertise and the Evolution of Intellect in Monkeys, Apes, and Humans 285–305 (Clarendon, Oxford, 1988).
DeCasien, A. R., Williams, S. A. & Higham, J. P. Primate brain size is predicted by diet but not sociality. Nat. Ecol. Evol. 1, 0112 (2017).
Sayol, F. et al. Environmental variation and the evolution of large brains in birds. Nat. Commun. 7, 13971 (2016).
Powell, L. E., Isler, K. & Barton, R. A. Re-evaluating the link between brain size and behavioural ecology in primates. Proc. R. Soc. B Biol. Sci. 284, 1–8 (2017).
Byrne, R. W. & Whiten, A. in Machiavellian Intelligence: Social Expertise and the Evolution of Intellect in Monkeys, Apes, and Humans. https://doi.org/10.2307/2804121 (Clarendon, Oxford, 1988).
Dunbar, R. I. M. The social brain hypothesis. Evol. Anthropol. Rev. 6, 178–190 (1998).
Ashton, B. J., Thornton, A. & Ridley, A. R. An intraspecific appraisal of the social intelligence hypothesis. Philos. Trans. R. Soc. B Biol. Sci. 373, 20170288 (2018).
Holekamp, K. E. Questioning the social intelligence hypothesis. Trends Cogn. Sci. 11, 65–69 (2007).
Kern, J. M. & Radford, A. N. Experimental evidence for delayed contingent cooperation among wild dwarf mongooses. Proc. Natl Acad. Sci. USA 115, 6255–6260 (2018).
Borgeaud, C. & Bshary, R. Wild vervet monkeys trade tolerance and specific coalitionary support for grooming in experimentally induced conflicts. Curr. Biol. 25, 3011–3016 (2015).
Moll, H. & Tomasello, M. Cooperation and human cognition: the Vygotskian intelligence hypothesis. Philos. Trans. R. Soc. B Biol. Sci. 362, 639–648 (2007).
van Schaik, C. P., Isler, K. & Burkart, J. M. Explaining brain size variation: from social to cultural brain. Trends Cogn. Sci. 16, 277–284 (2012).
Lucas, J. R., Gentry, K. E., Sieving, K. E. & Freeberg, T. M. Communication as a fundamental part of Machiavellian intelligence. J. Comp. Psychol. 132, 442–454 (2018).
Dunbar, R. I. M. & Shultz, S. Why are there so many explanations for primate brain evolution? Philos. Trans. R. Soc. B Biol. Sci. 372, 20160244 (2017).
Dunbar, R. I. M. & Shultz, S. Understanding primate brain evolution. Philos. Trans. R. Soc. B Biol. Sci. 362, 649–658 (2007).
Shultz, S. & Dunbar, R. I. M. Social bonds in birds are associated with brain size and contingent on the correlated evolution of life-history and increased parental investment. Biol. J. Linn. Soc. 100, 111–123 (2010).
Shultz, S. & Dunbar, R. I. M. The evolution of the social brain: anthropoid primates contrast with other vertebrates. Proc. R. Soc. B Biol. Sci. 274, 2429–2436 (2007).
Lemoine, S. et al. Between-group competition impacts reproductive success in wild chimpanzees. Curr. Biol. 30, 312–318.e3 (2020).
Adams, E. S. Approaches to the study of territory size and shape. Annu. Rev. Ecol. Syst. 32, 277–303 (2001).
Hardy, I. C. W. & Briffa, M. Animal Contests (Cambridge Univ. Press, Cambridge, 2013).
Radford, A. N., Majolo, B. & Aureli, F. Within-group behavioural consequences of between-group conflict: a prospective review. Proc. R. Soc. B Biol. Sci. 283, 20161567 (2016).
van Schaik, C. P. in Comparative Socioecology (eds. Standen, V. & Foley, R. A.) 195–218 (Blackwell, 1989).
Wrangham, R. W. An ecological model of female-bonded primate groups. Behaviour 75, 262–300 (1980).
Sterck, E. H. M. The evolution of female social relationships in nonhuman primates. Behav. Ecol. Sociol. 291–309 (1997).
Wilson, M. L. & Wrangham, R. W. Intergroup relations in chimpanzees. Annu. Rev. Anthropol. 32, 363–392 (2003).
Moser-Purdy, C., MacDougall-Shackleton, E. A. & Mennill, D. J. Enemies are not always dear: male song sparrows adjust dear enemy effect expression in response to female fertility. Anim. Behav. 126, 17–22 (2017).
Gherardi, F. Fighting behavior in hermit crabs: the combined effect of resource-holding potential and resource value in Pagurus longicarpus. Behav. Ecol. Sociobiol. 59, 500–510 (2006).
Alexander, R. D. in The Human Revolution (eds. Mellars, P. & Stringer, C.) 455–513 (Edinburgh Univ. Press, Edinburgh, 1984).
Hamilton, W. D. in ASA Studies 4: Biosocial Anthropology (ed. Fox, R.) 133–153 (Malaby, 1975).
Grueter, C. C. Home range overlap as a driver of intelligence in primates. Am. J. Primatol. 77, 418–424 (2015).
Reichert, M. S. & Quinn, J. L. Cognition in contests: mechanisms, ecology, and evolution. Trends Ecol. Evol. 32, 773–785 (2017).
Shettleworth, S. J. Cognition, Evolution, and Behavior (Oxford Univ. Press, 2010).
Young, A. J., Spong, G. & Clutton-Brock, T. Subordinate male meerkats prospect for extra-group paternity: alternative reproductive tactics in a cooperative mammal. Proc. R. Soc. B Biol. Sci. 274, 1603–1609 (2007).
Radford, A. N. & du Plessis, M. A. Territorial vocal rallying in the green woodhoopoe: factors affecting contest length and outcome. Anim. Behav. 68, 803–810 (2004).
Geissmann, T. & Orgeldinger, M. The relationship between duet songs and pair bonds in siamangs, Hylobates syndactylus. Anim. Behav. 60, 805–809 (2000).
Ridley, A. R. in Cooperative Breeding in Vertebrates: Studies of Ecology, Evolution and Behavior. 115–132. https://doi.org/10.1017/CBO9781107338357.008 (Cambridge Univ. Press, 2016).
Bee, M. A. Habituation and sensitization of aggression in bullfrogs (Rana catesbeiana): testing the dual-process theory of habituation. J. Comp. Psychol. 115, 307–316 (2001).
Sheehan, M. J. & Tibbetts, E. A. Selection for individual recognition and the evolution of polymorphic identity signals in Polistes paper wasps. J. Evol. Biol. 23, 570–577 (2010).
Cant, M. A., Otali, E. & Mwanguhya, F. Fighting and mating between groups in a cooperatively breeding mammal, the banded mongoose. Ethology 108, 541–555 (2002).
Braga Goncalves, I. & Radford, A. N. Experimental evidence that intruder and group member attributes affect outgroup defence and associated within-group interactions in a social fish. Proc. R. Soc. B Biol. Sci. 286, 20191261 (2019).
Szipl, G., Ringler, E. & Bugnyar, T. Attacked ravens flexibly adjust signalling behaviour according to audience composition. Proc. R. Soc. B Biol. Sci. 285, 20180375 (2018).
Noser, R. & Byrne, R. W. Mental maps in chacma baboons (Papio ursinus): Using inter-group encounters as a natural experiment. Anim. Cogn. 10, 331–340 (2007).
Radford, A. N. Preparing for battle? Potential intergroup conflict promotes current intragroup affiliation. Biol. Lett. 7, 26–29 (2011).
Christensen, C. & Radford, A. N. Dear enemies or nasty neighbors? Causes and consequences of variation in the responses of group-living species to territorial intrusions. Behav. Ecol. 29, 1004–1013 (2018).
Temeles, E. J. The role of neighbours in territorial systems: when are they ‘dear enemies’? Anim. Behav. 47, 339–350 (1994).
Radford, A. N. Group-specific vocal signatures and neighbour-stranger discrimination in the cooperatively breeding green woodhoopoe. Anim. Behav. 70, 1227–1234 (2005).
Hyman, J. & Hughes, M. Territory owners discriminate between aggressive and nonaggressive neighbours. Anim. Behav. 72, 209–215 (2006).
Monclús, R., Saavedra, I. & de Miguel, J. Context-dependent responses to neighbours and strangers in wild European rabbits (Oryctolagus cuniculus). Behav. Process. 106, 17–21 (2014).
Thompson, F. J., Marshall, H. H., Vitikainen, E. I. K. & Cant, M. A. Causes and consequences of intergroup conflict in cooperative banded mongooses. Anim. Behav. 126, 31–40 (2017).
McComb, K., Packer, C. & Pusey, A. Roaring and numerical assessment in contests between groups of female lions, Panthera leo. Anim. Behav. 47, 379–387 (1994).
Descovich, K. A., Lisle, A. T., Johnston, S., Nicolson, V. & Phillips, C. J. C. Differential responses of captive southern hairy-nosed wombats (Lasiorhinus latifrons) to the presence of faeces from different species and male and female conspecifics. Appl. Anim. Behav. Sci. 138, 110–117 (2012).
Christensen, C., Kern, J. M., Bennitt, E. & Radford, A. N. Rival group scent induces changes in dwarf mongoose immediate behavior and subsequent movement. Behav. Ecol. 27, 1627–1634 (2016).
Trimmer, P. C. & Houston, A. I. An evolutionary perspective on information processing. Top. Cogn. Sci. 6, 312–330 (2014).
Mares, R., Young, A. J., Levesque, D. L., Harrison, N. & Clutton-Brock, T. H. Responses to intruder scents in the cooperatively breeding meerkat: sex and social status differences and temporal variation. Behav. Ecol. 22, 594–600 (2011).
Humphries, D. J., Finch, F. M., Bell, M. B. V. & Ridley, A. R. Vocal cues to identity: pied babblers produce individually distinct but not stable loud calls. Ethology 122, 609–619 (2016).
Burgener, N., Dehnhard, M., Hofer, H. & East, M. L. Does anal gland scent signal identity in the spotted hyaena? Anim. Behav. 77, 707–715 (2009).
Lanchester, F. W. W. Aircraft in Warfare: the Dawn of the Fourth Arm. (Constable and Company Limited, 1916).
Wilson, M. L., Britton, N. F. & Franks, N. R. Chimpanzees and the mathematics of battle. Proc. R. Soc. B Biol. Sci. 269, 1107–1112 (2002).
Plowes, N. J. R. & Adams, E. S. An empirical test of Lanchester’s square law: mortality during battles of the fire ant Solenopsis invicta. Proc. R. Soc. B Biol. Sci. 272, 1809–1814 (2005).
Radford, A. N. Territorial vocal rallying in the green woodhoopoe: influence of rival group size and composition. Anim. Behav. 66, 1035–1044 (2003).
van Schaik, C. P. et al. Male monkeys use punishment and coercion to de-escalate costly intergroup fights. Proc. R. Soc. B Biol. Sci. 285, 20172323 (2018).
Boydston, E. E., Morelli, T. L. & Holekamp, K. E. Sex differences in territorial behavior exhibited by the spotted hyena (Hyaenidae, Crocuta crocuta). Ethology 107, 369–385 (2001).
McComb, K., Pusey, A., Packer, C. & Grinnell, J. Female lions can identify potentially infanticidal males from their roars. Proc. R. Soc. B Biol. Sci. 252, 59–64 (1993).
Koch, F., Signer, J., Kappeler, P. M. & Fichtel, C. Intergroup encounters in Verreaux’s sifakas (Propithecus verreauxi): who fights and why? Behav. Ecol. Sociobiol. 70, 797–808 (2016).
Schindler, S., Radford, A. N. & Schindler, S. Factors influencing within-group conflict over defence against conspecific outsiders seeking breeding positions. Proc. R. Soc. B Biol. Sci. 285, 20181669 (2018).
Arseneau-Robar, T. J. M. et al. Female monkeys use both the carrot and the stick to promote male participation in intergroup fights. Proc. R. Soc. B Biol. Sci. 283, 20161817 (2016).
Radford, A. N. Duration and outcome of intergroup conflict influences intragroup affiliative behaviour. Proc. R. Soc. B Biol. Sci. 275, 2787–2791 (2008).
Tibbetts, E. A., Agudelo, J., Pandit, S. & Riojas, J. Transitive inference in Polistes paper wasps. Biol. Lett. 15, 20190015 (2019).
Grosenick, L., Clement, T. S. & Fernald, R. D. Fish can infer social rank by observation alone. Nature 445, 429–432 (2007).
Arseneau-Robar, T. J. M., Taucher, A. L., Schnider, A. B., van Schaik, C. P. & Willems, E. P. Intra- and interindividual differences in the costs and benefits of intergroup aggression in female vervet monkeys. Anim. Behav. 123, 129–137 (2017).
Kotrschal, A., Räsänen, K., Kristjánsson, B. K., Senn, M. & Kolm, N. Extreme sexual brain size dimorphism in sticklebacks: a consequence of the cognitive challenges of sex and parenting? PLoS ONE 7, e30055 (2012).
Garamszegi, L. Z., Eens, M., Erritzøe, J. & Møller, A. P. Sperm competition and sexually size dimorphic brains in birds. Proc. R. Soc. B Biol. Sci. 272, 159–166 (2005).
Willems, E. P. & Van Schaik, C. P. Collective action and the intensity of between-group competition in nonhuman primates. Behav. Ecol. 26, 625–631 (2015).
Kotrschal, A. et al. Artificial selection on relative brain size in the guppy reveals costs and benefits of evolving a larger brain. Curr. Biol. 23, 168–171 (2013).
Kotrschal, A., Corral-Lopez, A. & Kolm, N. Large brains, short life: selection on brain size impacts intrinsic lifespan. Biol. Lett. 15 (2019).
Tsuboi, M. et al. Comparative support for the expensive tissue hypothesis: big brains are correlated with smaller gut and greater parental investment in Lake Tanganyika cichlids. Evolution 69, 190–200 (2015).
Kotrschal, A., Kolm, N. & Penn, D. J. Selection for brain size impairs innate, but not adaptive immune responses. Proc. R. Soc. B Biol. Sci. 283 (2016).
Gervais, M. M., Kline, M., Ludmer, M., George, R. & Manson, J. H. The strategy of psychopathy: primary psychopathic traits predict defection on low-value relationships. Proc. R. Soc. B Biol. Sci. 280, 20122773 (2013).
Creel, S. & Christianson, D. Relationships between direct predation and risk effects. Trends Ecol. Evol. 23, 194–201 (2008).
Bruintjes, R., Lynton-Jenkins, J., Jones, J. W. & Radford, A. N. Out-group threat promotes within-group affiliation in a cooperative fish. Am. Nat. 187, 274–282 (2015).
Mosser, A. & Packer, C. Group territoriality and the benefits of sociality in the African lion, Panthera leo. Anim. Behav. 78, 359–370 (2009).
Crofoot, M. C., Gilby, I. C., Wikelski, M. C. & Kays, R. W. Interaction location outweighs the competitive advantage of numerical superiority in Cebus capucinus intergroup contests. Proc. Natl Acad. Sci. USA 105, 577–581 (2008).
Shaw, R. C., Boogert, N. J., Clayton, N. S. & Burns, K. C. Wild psychometrics: evidence for ‘general’ cognitive performance in wild New Zealand robins, Petroica longipes. Anim. Behav. 109, 101–111 (2015).
Buechel, S. D., Boussard, A., Kotrschal, A., van Der Bijl, W. & Kolm, N. Brain size affects performance in a reversal-learning test. Proc. R. Soc. B Biol. Sci. 285, 20172031 (2018).
Kotrschal, A., Deacon, A. E., Magurran, A. E. & Kolm, N. Predation pressure shapes brain anatomy in the wild. Evol. Ecol. 31, 619–633 (2017).
Herculano-Houzel, S. & Lent, R. Isotropic fractionator: a simple, rapid method for the quantification of total cell and neuron numbers in the brain. J. Neurosci. 25, 2518–2521 (2005).
Ashton, B. J., Ridley, A. R., Edwards, E. K. & Thornton, A. Cognitive performance is linked to group size and affects fitness in Australian magpies. Nature 61, 5985–5991 (2018).
Taborsky, B. & Oliveira, R. F. Social competence: an evolutionary approach. Trends Ecol. Evol. 27, 679–688 (2012).
Gonda, A., Herczeg, G. & Merilä, J. Evolutionary ecology of intraspecific brain size variation: a review. Ecol. Evol. 3, 2751–2764 (2013).
Morris-Drake, A. et al. Experimental field evidence that out-group threats influence within-group behavior. Behav. Ecol. 30, 1425–1435 (2019).
Hellmann, J. K. & Hamilton, I. M. Intragroup social dynamics vary with the presence of neighbors in a cooperatively breeding fish. Curr. Zool. 65, 21–31 (2018).
Healy, S. D. & Rowe, C. A critique of comparative studies of brain size. Proc. R. Soc. B Biol. Sci. 274, 453–464 (2007).
Kotrschal, A. et al. The benefit of evolving a larger brain: big-brained guppies perform better in a cognitive task. Anim. Behav. 86, e4–e6 (2013).
Whiten, A. Social, Machiavellian and cultural cognition: a golden age of discovery in comparative and evolutionary psychology. J. Comp. Psychol. 132, 437–441 (2018).
Radford, A. N. & Bruintjes, R. Expanding the link between out-group threats and in-group behavior (a reply to Kavaliers and Choleris). Am. Nat. 189, 459–462 (2017).
Brown, M. Food and range defence in group-living primates. Anim. Behav. 85, 807–816 (2013).
Mirville, M. O. et al. Factors influencing individual participation during intergroup interactions in mountain gorillas. Anim. Behav. 144, 75–86 (2018).
Sheldahl, L. A. & Martins, E. P. The territorial behavior of the western fence lizard, Sceloporus occidentalis. Herpetologica 56, 469–479 (2000).
Ward, M. P., Alessi, M., Benson, T. J. & Chiavacci, S. J. The active nightlife of diurnal birds: extraterritorial forays and nocturnal activity patterns. Anim. Behav. 88, 175–184 (2014).
Feldblum, J. T., Manfredi, S., Gilby, I. C. & Pusey, A. E. The timing and causes of a unique chimpanzee community fission preceding Gombe’s “Four-Year War”. Am. J. Phys. Anthropol. 166, 730–744 (2018).
Source: Ecology - nature.com
