L'existence, dans de nombreuses espèces, de comportements coopératifs entre individus non-apparentés constitue un paradoxe apparent pour la théorie de l'évolution. L'explication la plus acceptée est que les comportements coopératifs peuvent être « incités » par un mécanisme qui récompense les coopérateurs et punit les tricheurs. On parle alors de « coopération conditionnelle ». La majorité des travaux en théorie des jeux évolutionnaires cherchent seulement à expliquer comment des comportements coopératifs en général peuvent exister à un équilibre évolutionnaire. Dans cette thèse, nous cherchons au contraire à montrer que la théorie des jeux évolutionnaires peut aussi permettre de comprendre certaines des propriétés fines des comportements coopératifs qu'on observe dans le vivant, en particulier dans le cas de l'espèce humaine. Tout d'abord, nous posons la question de l'origine de la coopération conditionnelle. Comment la coopération conditionnelle peut-elle évoluer à partir d'une situation initiale dans laquelle personne ne coopère ? A l'aide de méthodes empruntées à l'apprentissage automatique, nous montrons que la coopération conditionnelle peut évoluer en tant que sous-produit d'une adaptation à des interactions dans lesquelles les intérêts des participants sont alignés. Nous montrons également que ce processus évolutif ne peut aboutir qu'à deux résultats opposés. Soit toutes les opportunités de coopération sont « trouvées » par l'évolution, ce qui correspond à la prévalence des comportements coopératifs chez l'Homme, soit un nombre très réduit d'opportunités de coopération sont « trouvées », ce qui correspond aux comportements coopératifs non humains. Nous proposons également une variante de ce modèle qui permet d'expliquer pourquoi de nombreux mutualismes sont des formes exagérées de cas d'interactions basées sur des intérêts communs. Dans un second temps, nous nous concentrons sur un mécanisme particulier de coopération conditionnelle : le choix du partenaire. Nous utilisons des simulations individu-centrées, et nous montrons que si l'on peut choisir librement ses partenaires dans la coopération, alors le seul niveau d'effort investi dans la coopération qui est évolutivement stable est celui qui maximise l'efficacité sociale de la coopération. Puis, nous développons des modèles analytiques, importés de la théorie économique des appariements. Nous montrons que la seule distribution des bénéfices générés par la coopération qui est évolutivement stable ne dépend pas des rapports de force et est proportionnelle à la contribution de chacun des participants. Ainsi, la théorie du choix du partenaire explique deux propriétés fines des comportements coopératifs chez l'Homme : nos préférences pour les formes de coopération les plus socialement efficaces et notre sens de l'équité. Enfin, nous montrons que la théorie des signaux coûteux, appliquée à la coopération, peut expliquer plusieurs propriétés de la réputation morale, puis nous concluons en discutant de futures directions de recherche. / The existence of cooperation among non-kin in many species constitutes an apparent paradox for evolutionary biologists. The most commonly accepted explanation is that cooperation can be enforced by mechanisms that reward cooperators or punish cheaters. Most of the theoretical works in evolutionary game theory, however, aim only at explaining how some cooperation can exist at an evolutionary equilibrium, thanks to these enforcement mechanisms. Here, we aim at showing, instead, that evolutionary game theory can also explain the fine-grained properties of the cooperation that takes place in the living world, especially in the case of the human species. First, we address the question of the origin of enforced cooperation: How can enforced cooperation evolve from an initially non-cooperative state? Using tools from the field of machine learning, we show that enforced cooperation can evolve as a by-product of adaptation to interactions with shared interests. We also show that this process has only two possible evolutionary outcomes. Either all cooperative opportunities are enforced, which corresponds to the human cooperative syndrome, or only a very few number are, which corresponds to non-human cooperation. We also propose a variation of this model to explain why many mutualisms are exaggerated forms of cooperation with shared interests. In a second approach, we focus on one specific enforcement mechanism called partner choice. Using agent-based simulations, we show that, when individuals can freely choose their cooperative partners, the only level of effort invested into cooperation that is evolutionarily stable is the one that maximizes the social efficiency of cooperation. We then build analytical models of partner choice imported from economic matching theory. We show that the only evolutionarily stable distribution of the benefits of cooperation is both independent of bargaining power and proportional to each participant's relative contribution. Thus, partner choice explains two fine-grained properties of human cooperation, namely our preferences for the most socially efficient forms of cooperation and our concerns for fair distributions. Finally, we show that costly signalling models of cooperation can explain several properties of moral reputation, and we conclude by discussing directions for future research.

This diploma thesis traces the changing human, animal and technology assemblage after the recent emergence of wolf packs in Broumov region. As the return of wolves coincides with ecological transformations gaining in strength, the central research focus are the possibilities - and impossibilities - of local multispecies coexistence in the conditions of Anthropocene. The research draws upon methods of multispecies ethnography, building on the literature that examines the ontological aspects of multispecies coexistence, including primarily the work of Donna Haraway, Eduardo Kohn, Annemarie Mol, Anna Tsing and Rane Willerslev. The thesis analyzes several modes of situated multispecies coexistence which have been reconfigured or made possible by the return of wolves: administrative and sensual practice of shepherds, methods of mimetic empathy of wolf trackers, emergence of new actors interfering with local events (satellites, subsidy programmes, drought) and the translation of processes on pastures into politically engaged activities of local farmers. The thesis develops the employed concepts in such a way that they enable analyzing the situation in Broumov region as situated making of more-than-human sociality. Key words: multispecies ethnography, wolfs, pastoralism, trackers, more-than-human sociality

This thesis focuses on the interspecies relationships of care in the Hambach Forest, Germany. It covers the caring relations between the human activists protecting the Forest by occupying it and the trees growing there. The text covers the affectionate dimension of the activists’ caring relation towards the trees as well as how the caring manifested in their attentiveness and actions. Apart from the traditional ethnographic methods, the research is rooted in multispecies methodology, particularly plant ethnography. As primary theoretical frameworks, the concepts of more-than human sociality and world-making by Anna Tsing were used, as well as the understanding of the interspecies ethics of care by Puig de la Bellacasa. The analysis shows that the caring relationship of the activists was often rooted in the situated relationality that emerges from particular relations with particular trees or other nonhumans. As a navigating tool, activists sometimes used also the nature-culture dichotomy, and sometimes they, on the contrary, contested it. I show that relationships of care were mutual and occurred in the direction from activists to the trees but also that the trees and Forest took care of many activists’ needs. I also demonstrate how the trees and other nonhumans actively participated in the processes of co-creating the more-than-human sociality in the Forest. The analysis shows that the activists’ behaviour was not always coherent or determined by the same values but was often ambivalent and changing depending on the situation.