To explain the evolutionary emergence of uniquely human skills and motivations for cooperation, Tomasello et al. (2012, in Current Anthropology 53(6):673–92) proposed the interdependence hypothesis. The key adaptive context in this account was the obligate collaborative foraging of early human adults. Hawkes (2014, in Human Nature 25(1):28–48), following Hrdy (Mothers and Others, Harvard University Press, 2009), provided an alternative account for the emergence of uniquely human cooperative skills in which the key was early human infants’ attempts to solicit care and (...) attention from adults in a cooperative breeding context. Here we attempt to reconcile these two accounts. Our composite account accepts Hrdy’s and Hawkes’s contention that the extremely early emergence of human infants’ cooperative skills suggests an important role for cooperative breeding as adaptive context, perhaps in early Homo. But our account also insists that human cooperation goes well beyond these nascent skills to include such things as the communicative and cultural conventions, norms, and institutions created by later Homo and early modern humans to deal with adult problems of social coordination. As part of this account we hypothesize how each of the main stages of human ontogeny (infancy, childhood, adolescence) was transformed during evolution both by infants’ cooperative skills “migrating up” in age and by adults’ cooperative skills “migrating down” in age. (shrink)

Examining the costs and motivations of warfare is key to conundrums concerning the relevance of this troubling phenomenon to the evolution of social attachment and cooperation, particularly during adolescence and young adulthood—the developmental time period during which many participants are first recruited for warfare. The study focuses on Samburu, a pastoralist society of approximately 200,000 people occupying northern Kenya’s semi-arid and arid lands, asking what role the emotionally sensitized, peer-driven adolescent life stage may have played in the cultural and genetic (...) coevolution of coalitional lethal aggression. Research in small-scale societies provides unparalleled opportunities for sharply defined variables, particularly in age generation societies in which all young men are initiated into “warriorhood.” Proposing an epigenetic and component behavior approach, we examine whether raiding activities such as number of raids, killing, and sparing enemy lives associate with DNA methylation in two candidate genes: MAOA, linked to mood and arousal, and NR3C1, linked to stress and immune response. We report statistically significant associations between the epigenetic variables and the combat variables of overall raiding activity and reportedly showing mercy to enemies. In contrast, epigenetic variables did not associate with post-traumatic stress disorder symptom scores, and the only combat variable associated with PTSD was losing one’s own livestock in a raid. These findings raise important questions concerning the mechanisms driving warfare’s paradoxical mix of violent and altruistic behaviors. (shrink)

This study investigates how allomaternal care impacts human development outside of energetics by evaluating relations between important qualitative and quantitative aspects of AMC and developmental outcomes in a Western population. This study seeks to determine whether there are measurable differences in cognitive and language outcomes as predicted by differences in exposure to AMC via formal and informal networks. Data were collected from 102 mothers and their typically developing infants aged 13–18 months. AMC predictor data were collected using questionnaires, structured daily (...) diaries, and longitudinal interviews. Developmental outcomes were assessed using the Cognitive, Receptive Language, and Expressive Language subtests of the Bayley III Screening Test. Additional demographic covariates were also evaluated. Akaike Information Criterion -informed model selection was used to identify the best-fitting model for each outcome across three working linear regression models. Although AMC variables had no significant effects on Receptive and Expressive Language subtest scores, highly involved familial AMC had a significant medium effect on Cognitive subtest score. Formal childcare had no effect on any outcome. This study provides preliminary evidence that there is a measurable connection between AMC and cognitive development in some populations and provides a methodological base from which to assess these connections cross-culturally through future studies. As these effects are attributable to AMC interactions with networks of mostly related individuals, these findings present an area for further investigation regarding the kin selection hypothesis for AMC. (shrink)

This first part of a two‐part article illustrates how research in evolutionary biology and psychology illuminates questions arising in philosophy—specifically questions about the origins of severe, systemic aggression that arise in the mimetic theory of René Girard. Part I looks at: (i) how old the systemic practice of severe aggression is, (ii) how much results from humanity's mimetic/social and competitive nature and how much from ecological, resource, and cultural conditions, and (iii) if ecological and cultural conditions are important, might we (...) adapt them toward greater cooperativity today? After briefly reviewing mimetic theory, the article looks at evolutionary psychology and biology, including fossil and archeological evidence. Findings suggest that severe, systemic aggression might be relatively recent and that its occurrence depends on ecological/resource/socioeconomic conditions additional to our mimetic/social nature. Thus, distinguishing the conditions that prod aggression from those that support pro‐social behavior might aid us in structuring society today. (shrink)

This Part II of a two‐part article illustrates how research in evolutionary biology, anthropology, archeology, and psychology illuminates questions arising in philosophy—specifically questions about René Girard's theory of aggression. Part I looked at: (i) how old the systemic practice of severe aggression is; (ii) how much of it results from humanity's mimetic/social and competitive nature and how much from ecological, resource, and cultural conditions; and (iii) if ecological, resource, and cultural conditions are important, might we adapt this information toward greater (...) cooperativity today? Part II investigates Girard's theory of ritual sacrifice—especially human sacrifice—as a societal steam valve for the systemic aggression explored in Part I. It draws on theories of play, theater, and art to examine the role and function of such ritual sacrifice. (shrink)

Joint attention is an early-emerging and uniquely human capacity that lies at the foundation of many other capacities of humans, such as language and the understanding of other minds. In this article, I summarize what developmentalists and philosophers have come to find out about joint attention, and I end by stating that two problems or questions of joint attention require additional research: 1) the relation between joint attention and the skills for dyadic sharing or affect exchange in young infants, and (...) 2) the evolution of joint attention. (shrink)

Stories do not fossilize. Thus, exploring tales shared during prehistory, the longest part of human history inevitably becomes speculative. Nevertheless, various attempts have been made to find a more scientifically valid way into our deep human past of storytelling. Following the social brain hypothesis, we suggest including into the theory of human storytelling more fine-grained and evidence-based findings about the manifold exaptation and adaptation, genetic changes, and phenotypic plasticity in the deep human past, which all shaped the emergence of storytelling (...) in hominins. We identify three preconditions for humans sharing stories: first, the long evolution of language in the different taxa as one of the preconditions of ostensive signaling; second, the pivotal role of childhood in the evolution of collaborative intentionality; and third, the role of fireside chats in the rise of elaborative sharing of stories. We propose that humans, albeit perhaps no other hominins learned to understand others through sharing stories, not only as intentional agents, but also as mental ones. (shrink)

The authors propose that many morbidities higher in women than men are adaptations protecting survival, selected because survival has been especially crucial to mothers' reproductive success. Following their lead, I pursue variation in tradeoffs between reproduction and survival recognized by Darwin that were likely central to the evolution of many traits that distinguish us from our great ape cousins.

Discussions about the evolution of human social cognition usually portray the social environment of early hominins as highly hierarchical and violent. In this evolutionary narrative, our propensity for violence was overcome in our lineage by an increase in our intellectual capacities. However, I will argue in this article that we are at least equally justified in believing that our early hominin ancestors were less aggressive and hierarchical than is suggested in these models. This view is consistent with the available comparative (...) and palaeoanthropological evidence. I will show that this alternative model not only does not support long-held views of human origins, but also has important consequences for debates about the evolution of our capacity for normative guidance. _1_ Introduction _2_ Philosophical Motivation _3_ The Puzzle of Hominin Evolution _4_ The Mosaic Hypothesis _5_ Evidence for the Model _6_ Palaeoanthropological Support _7_ Philosophical Consequences. (shrink)

Discussions about the evolution of human social cognition usually portray the social environment of early hominins as highly hierarchical and violent. In this evolutionary narrative, our propensity for violence was overcome in our lineage by an increase in our intellectual capacities. However, I will argue in this article that we are at least equally justified in believing that our early hominin ancestors were less aggressive and hierarchical than is suggested in these models. This view is consistent with the available comparative (...) and palaeoanthropological evidence. I will show that this alternative model not only does not support long-held views of human origins, but also has important consequences for debates about the evolution of our capacity for normative guidance. 1Introduction 2Philosophical Motivation 3The Puzzle of Hominin Evolution 4The Mosaic Hypothesis 5Evidence for the Model 6Palaeoanthropological Support 7Philosophical Consequences. (shrink)

We consider the evolutionary scheme of morality proposed by Tomasello to defend the idea that the ability to orient the learning of offspring using signs of approval/disapproval could be a decisive and necessary step in the evolution of human morality. Those basic forms of intentional evaluative feedback, something we have called assessor teaching, allow parents to transmit their accumulated experience to their children, both about the behaviors that should be learned as well as how they should be copied. The rationale (...) underlying this process is as follows: if a behavior is approved, then it is good; if it is disapproved, then it is bad. The evaluative guidance on how to behave most probably spread among peers in situations of mutual benefit, such as cooperative child rearing. We argue that our hominin ancestors provided with this capacity for assessor teaching were ideally positioned to develop the two specifically human levels of morality proposed by Tomasello: the morality of fairness and the morality of justice. Assessor teaching could have facilitated the genesis of rudimentary codes of behavior tied with the need to agree about how to behave to succeed in joint cooperative activities. Moreover, learning through assessor teaching provides a plausible explanation for the origin of the objectivist and prescriptive dimensions of human morality. First, we emphasize that individuals feel that they evaluate the behavior of others objectively to guide their learning, and, second, we underline the imperative intention that any moral manifestation possesses. (shrink)

Language is a cognitively demanding human trait, but it is also a fundamentally cooperative enterprise that rests on the motivation to share information. Great apes possess many of the cognitive prerequisites for language, but largely lack the motivation to share information. Callitrichids (including marmosets and tamarins) are highly vocal monkeys that are more distantly related to humans than great apes are, but like humans, they are cooperative breeders and all group members help raising offspring. Among primates, this rearing system is (...) correlated with proactive prosociality, which can be expressed as motivation to share information. We therefore propose that the unique coincidence of these two components in humans set the stage for language evolution: The cognitive component inherited from our great ape-like ancestors, and the motivational one added convergently as a result of cooperative breeding. We evaluate this scenario based on a review of callitrichd vocal communication and show that furthermore, they possess many of the mechanistic elements emphasized by the mirror system hypothesis of language evolution. We end by highlighting how more systematic phylogenetic comparisons will enable us to further promote our understanding of the role of cooperative breeding during language evolution. (shrink)

For more than 100,000 years, H. sapiens lived as foragers, in small family groups with low reproductive variance. A minority of men were able to father children by two or three women; and a majority of men and women were able to breed. But after the origin of farming around 10,000 years ago, reproductive variance increased. In civilizations which began in Mesopotamia, Egypt, India, and China, and then moved on to Greece and Rome, kings collected thousands of women, whose children (...) were supported and guarded by thousands of eunuchs. Just a few hundred years ago, that trend reversed. Obligate sterility ended, and reproductive variance declined. For H. sapiens, as for other organisms, eusociality seems to be an effect of ecological constraints. Civilizations rose up in lake and river valleys, hemmed in by mountains and deserts. Egalitarianism became an option after empty habitats opened up. (shrink)

For more than 100,000 years, H. sapiens lived as foragers, in small family groups with low reproductive variance. A minority of men were able to father children by two or three women; and a majority of men and women were able to breed. But after the origin of farming around 10,000 years ago, reproductive variance increased. In civilizations which began in Mesopotamia, Egypt, India, and China, and then moved on to Greece and Rome, kings collected thousands of women, whose children (...) were supported and guarded by thousands of eunuchs. Just a few hundred years ago, that trend reversed. Obligate sterility ended, and reproductive variance declined. For H. sapiens, as for other organisms, eusociality seems to be an effect of ecological constraints. Civilizations rose up in lake and river valleys, hemmed in by mountains and deserts. Egalitarianism became an option after empty habitats opened up. (shrink)

This thesis focuses on the evolution of human social norm psychology. More precisely, I want to show how the emergence of our distinctive capacity to follow social norms and make social normative judgments is connected to the lineage explanation of our capacity to form shared intentions, and how such capacity is related to a diverse cluster of prototypical moral judgments. I argue that in explaining the evolution of this form of normative cognition we also require an understanding of the developmental (...) trajectory of this capacity. For this purpose, the thesis is organized as follow. In the first chapter, I make some methodological remarks and provide the general overview and plan for the dissertation. In the second chapter, I explain what my explanatory target is and why it matters. On the view I am defending, shared intentional psychology gives rise to a special form of psychology that enables us to engage in social normative thinking. These norms are represented as shared intentional states. Moral psychology, in contrast, is more diverse. For moral judgments define a quite heterogeneous class of mental states—although some moral judgments may involve the representation and execution of norms, certainly not all of them do. I show that although much of our distinctive social norm psychology can be explained within the framework of shared intentionality, moral judgments cannot be unified in the same way. In the third chapter, I provide the baseline of social-cognitive capacities that serve as starting point for my lineage explanation. I argue that hominin social cognition was for a very long period of our evolutionary history essentially a matter of low-level cognitive and motivational processes. On this picture, bottom-up affective processes regulated the social lives of early hominins without requiring any special top-down mechanism of normative thinking such as a capacity for understanding and representing social norms. In the fourth chapter, I argue that human-like social norm psychology evolved as a result of the selective pressures that gave rise to shared intentionality, especially the demands that came from collective hunting. Yet collective hunting was not the whole story of the evolution of shared intentionality, for our capacity to form shared intentional mental states emerged from the interplay between the selective pressures that led to cooperative breeding in humans as well as organized, goal-oriented, collective hunting. Thus, I propose an evo-devo account of shared intentionality and its normative dimension since I argue that explaining the evolution of this particular form of normative thinking crucially depends on information about the developmental trajectory of this capacity. Finally, in the fifth chapter, I focus on how social norms are acquired and how the way we learn them gives rise to some prototypical cluster of moral judgments. Thus, this chapter returns to some of themes and arguments of the first chapter by explaining how the distinction between moral judgments and nonmoral judgments can be culturally transmitted. (shrink)