Becoming Human is Michael Tomasello's herculean endeavour to systematise more than two decades of research, conducted by him and his colleagues at the Department of Developmental and Comparative Psychology at the Max Planck Institute for Evolutionary Anthropology in Leipzig. The unifying frame is the shared intentionality hypothesis which, in broad outline, says that what underpins the possibility of human culture and makes us uniquely human are pervasive forms of cooperation based on pro-social motivations for helping and sharing.
The emergence of cooperative motives is transformative. Great apes manifest some understanding of others in intentional terms, and self-regulate their psychological states and actions, but they do so mostly in competitive rather than cooperative contexts. Motivations to help and share allow humans to reorient capacities for individual intentionality toward the achievement of joint and collective goals. The emergence of shared intentionality has cascading effects for human psychology and is foundational for the development of linguistic communication, cultural learning, and social norms. In Becoming Human, Tomasello works out this hypothesis to a comprehensive account of the main pathways of human ontogeny, from birth to the end of the preschool period, which, according to Tomasello, is when children start to act in light of norms of rationality and morality.
More than 20 years ago, when considering the problem of explaining the emergence of thought from both an evolutionary and a developmental perspective, Donald Davidson remarked: ‘what we lack is a satisfactory vocabulary for describing the intermediate steps [from non-thinking to thinking creatures]’Footnote 1. In Becoming Human, philosophers will find important suggestions on how to fill in the lexical and conceptual gaps. Perhaps even more importantly, they will also find opportunities for thinking about age-old philosophical problems from the perspectives of comparative and developmental psychology. For instance, does communication, be it gestural or linguistic, hinge on capacities for reading minds or is it the other way around? Can the concept of belief be acquired absent language? How can human morality and social norms possibly have sprung from great apes’ sense of sympathy?
From the point of view of the philosophy of language and mind, the third and the fourth chapters are especially intriguing. They contain a balanced and neat reconstruction of Tomasello's views on language as originating in gestural communication, which, in a Gricean fashion, he conceives of as intentional and overt, and based on common ground. Importantly, Tomasello is now more explicit and precise on the cognitive and motivational underpinnings of Gricean communication. At the same time, he offers a suggestive explanation of how mastery of the concept of belief emerges, strictly speaking, from the third year onwards, when children start forming some robust linguistic competency and develop other subsidiary competencies for comparing how they see the world to how others might happen to see it.
Tomasello's prose is often seductive, and the experiments he discusses are often designed with great ingenuity. However, the reader should resist the temptation of being carried away and keep in mind that almost every significant claim put forward by Tomasello is still widely, and sometimes fiercely, debated (regarding problematic aspects of cross-species comparisons, see, e.g., Leavens et al. 2019; regarding mindreading and communication see, e.g., Rakoczy and Behne 2019).Footnote 2
Other reviewers (Moll et al. 2020 but see also Tomasello 2020 for a reply) have already highlighted several important specific points of originality.Footnote 3 In this review, I would like to give the reader a bird's eye view of Tomasello's project, and I would like do so by focusing on three structural features of his proposal: the background evolutionary hypothesis, the main methodological concern, and the qualification ‘Neo-Vygotskyan’. All three contain something that is importantly new and worth further inquiry.
From an evolutionary point of view, Tomasello's hypothesis sees human uniqueness as springing from two major sets of adaptations. The first set is composed of skills and motivations for joint intentionality, namely, those skills and motivations that enabled humans to cooperate with specific individuals on specific occasions. The second set of adaptations relate to skills and motivations for collective intentionality, which enabled humans to cooperate in the context of larger groups and self-regulate their own psychological states and actions from the point of view of the group itself. Skills and motivations for collective intentionality are foundational for the creation of social conventions and norms, as well as cultural institutions, and enabled humans to embark on larger-scale cultural endeavours.
According to Tomasello, skills and motivations for joint intentionality are adaptations for collaborative foraging, which became a necessity after a radiation of terrestrial monkeys occurred around 400,000 years ago. The fundamental components of joint intentionality are pro-social motivations for helping and sharing, which include, crucially, motivations for attuning to one another psychologically. According to Tomasello, these motivations, however they are to be spelled out, are manifest in infants’ early emotional engagements. Tomasello further argues that pro-social motivations were ontogenetic adaptations for the infancy period itself in the context of cooperative breeding, where infants had to solicit care and attention from adults other than their mothers, as well as having to compete with a greater number of siblings. Although Tomasello is keen on providing evidence in favour of the cooperative-breeding hypothesis, this point deserves further investigation, because it is unclear which selective pressures solicited which adaptations and how they did so. How did cooperative breeding come about? Does cooperative breeding predate cooperative foraging? Are pro-social motivations, which are foundational for joint actions, adaptations for cooperative foraging or for cooperative breeding, or both? And what sort of evidence would answer this question?
The second set of adaptations, which according to Tomasello must have occurred some 150,000/100,000 years ago, equipped humans with the socio-cognitive capacities for collective intentionality. The selective pressure identified by Tomasello is the formation of much larger human groups often competing with each other, which prompted the need for recognising others belonging to the same larger cultural group and for organising one's activities in a broader social context. A possible limitation of this second strand of Tomasello's evolutionary hypothesis is that he does not offer any detailed story about how the complex skills required by collective intentionality could have emerged. In other words, there is no story parallel to the one envisaged for joint intentionality and emotional engagement.
From a methodological point of view, Tomasello is interested in discerning the different contributions of maturational components, experiences, and processes of self-regulation to development. The distinction between maturation and experience is a welcome attempt at partly replacing distinctions such as nature and nurture, innate and learned. In broad outlines, capacities that have strong maturational components as, for instance, capacities for joint attentional engagements, develop in a predictable and narrow timeline and in a closely similar way in every typically developing individual that lives in a species-typical social environment. Therefore, even some of those capacities that are more genetically channelled will still need some robust experiencing of interactions with other individuals and the environment, but they will not require, for instance, very specific experiences or teachings.
Every ontogenetic pathway examined in Becoming Human contains sections on both cross-cultural variation and atypical development, which Tomasello takes as sources of evidence for discerning the different contributions of maturation and experience. The intuition is that capacities with strong maturational components should not show significant cross-cultural variation. On the other hand, the emergence of these capacities might be inhibited in individuals which have syndromes or conditions that, for independent reasons (and this is a problematic caveat), are thought of as having a strong biological basis.
The reader will find that structuring the exposition in this way is extremely useful, but, here as elsewhere, some caution is recommended. Since the ground covered in the book is so vast, Tomasello addresses some crucial aspects of the discussed experiments only in passim, if at all. For instance, studies with autistic individuals are often cited without telling the reader much about which segments of the autistic population have been examined or which control groups were used. To see why this is crucial, consider the following: Tomasello argues that joint attention is foundational for learning a language. Several well-known studies report that individuals later diagnosed with ASD showed impairments in joint attention. However, while indeed some autistic individuals never acquire a language, large portions of the autistic population do, even though they may show pragmatic deficits. At this point the reader might want to have a more nuanced explanation of how joint attention, language acquisition and language use work for different segments of the autistic population. Of course, giving such an explanation would constitute another herculean endeavour, so this is no objection to the theory proposed, but rather an invitation for the reader to further explore the studies recounted in Becoming Human.
Finally, Tomasello qualifies his theory as Neo-Vygotskyan. The fundamental Vygotskyan insight is that the higher functions of human psychology result, at least in part, from the internalization of socio-cultural practices, where these include, for instance, linguistic communication. Furthermore, according to Vygotsky it is of primary importance that, perhaps unwittingly, adults scaffold children to enable their participation in socio-cultural practices. The Vygotskyan notion of internalization has often been deemed mysterious with respect to its cognitive and motivational basis. Tomasello's contribution here is twofold. First, he explains the paradigmatic cases of internalization in terms of role-reversal imitation. For instance, and again simplifying brutally, a child will correct her own uses of language in pretty much the same way in which adults have corrected her before. Second, Tomasello emphasises processes of executive self-regulation and argues that humans, but not other primates, executively self-regulate their psychological states and actions from the perspective of others. For instance, they attune their communicative acts according to what is relevant to them and their partners in the context of certain interactions (joint intentionality) and later they adjust their utterances also to conventional norms of a natural language. Finally, Tomasello's proposal qualifies as Neo-Vygotskyan also because the shared intentionality hypothesis is meant to explain what Vygotsky could not explain in his lifetime, namely, the coordinative dimension of socio-cultural practices, how these practices have come about, and what socio-cognitive capacities humans must have to start participating in them.
Becoming Human is the capstone of the work conducted by Tomasello and colleagues over the past 20 years. It is great in details and in the landscape surveyed, and no short review can do justice to its complexities. This book will constitute an invaluable tool for researchers in the fields of psychology, linguistics, and philosophy, regardless of whether one will end up agreeing or disagreeing with Tomasello's conclusions and methods.
