In their chapter Core Cognition of Social Relations, Thomsen and Carey (Reference Thomsen and Carey2013) proposed

The only empirical demonstrations from human infants at the time of writing were the discovery that preverbal infants represent social dominance, using the formidability cue of relative size (Thomsen, et al., Reference Thomsen, Frankenhuis, Ingold-Smith and Carey2011) and Over and colleagues’ (Reference Over and Carpenter2009) demonstration that 18-month-olds more likely to help others if they have been primed with close, affiliative touch (i.e., communal sharing). This, then, is an exciting example of science moving on fast across many independent labs in a decade from the assumption that infants understand intentional agency (and whether agents help/hinder others in achieving their intentional goals), but ‘simply learn’ the other key aspects of the social world, to wide-spread hypotheses that some basic social relations manifest in the infant mind. Bringing a synthesis of much current evidence bearing on this general proposal before the scientific community for collective debate is an important contribution.

Thomas argues relational core cognition is for concrete, continuing interpersonal relationships. We argue instead that innate (shared) core cognition for abstract, skeletal relations coordinate social interaction at large and help solve the learnability problem of discovering the structure of the social world. It’s akin to a deep, generative grammar (Chomsky, Reference Chomsky1967/2006) in which social meaning is created and experienced. This evolved relational ‘grammar’ specifies “rules of the games of social and societal life in intuitive, taken-for-granted ways” (Thomsen, Reference Thomsen2020, p. 201), ultimately coordinating the distribution dilemmas of benefits and costs—resources, rights, obligations, and care—inherent in group life (Thomsen & Carey, Reference Thomsen and Carey2013; see also Ho et al., Reference Ho, Kteily, Sheehy-Skeffington and Thomsen2025; Sheehy-Skeffington & Thomsen, Reference Sheehy-Skeffington and Thomsen2020, Reference Thomsen2023; Thomsen, Reference Thomsen2020). Echoing at least the affordances of mammalian life, for instance, the impression of being one, categorical social body (summary representation of unity) is created by touch, spatial closeness, sharing food and bodily substances of breast milk, semen, saliva, and blood, moving in synchrony, and marking bodies to look alike (cues), in turn creating and prescribing the solidary sharing and caring (coordinated normative interaction) prototypically implemented among close kin, and the emotions that motivate it (Thomsen & Carey, Reference Thomsen and Carey2013; drawing on Fiske, Reference Fiske2004).

Whether one thinks relational core cognition is for coordinating and understanding rule-based social life or for representing enduring, concrete interpersonal relationships have implications for the interpretation of the empirical record. For instance, Thomas suggests Ziv & Sommerville (Reference Ziv and Sommerville2017) demonstrate expectations for even resource distribution, but not equality matching, because it is unclear if infants expect an enduring relationship. But these infants also gave away their own prized resource (toy), whereas infants expecting inequality refused to do so, reminiscent of the effects of social dominance orientation (SDO) on adult (in)egalitarian political ideology (Sheehy-Skeffington & Thomsen, Reference Sheehy-Skeffington and Thomsen2020, Reference Thomsen2023; Ho et al., Reference Ho, Kteily, Sheehy-Skeffington and Thomsen2025). This provides compelling evidence that core, abstract relational expectations motivate the navigation of resource dilemmas even in the infant mind.

Thomas also suggests there is no evidence that preverbal infants use relative size as cue for the dominance version of hierarchical relationships, because size is an individual trait that does not specify if people will keep on interacting. But size has no inherent meaning as an individual trait—like win-lose history and number of allies, it is a transitive formidability cue that only predicts the mutual coordination of yielding and prevailing in zero-sum conflict relative (i.e., ‘relational’) to others’ formidability; repeated, coordinated interactions that over time will coalesce into an asymmetrical relationship of stable, transitive rank (which Gazes, Hampton, & Lourenco, Reference Gazes, Hampton and Lourenco2017 confirmed that infants understand). Whether people keep on interacting is distinct from representing the adaptive affordances of this relational coordination, though its degree of asymmetry will reflect previous rank-based interactions. Following this, I doubt toddlers interpreted a relationship of prestige or a caregiver, rather than stable dominance rank, in our puppet version of the right-of-way dominance paradigm (Thomas et al.) because toddlers only chose individuals for whom others bow and move away in contexts of zero-sum conflict: Being bowed before without prevailing in conflict because the other yielded—a key indicator of stable dominance rank with critical adaptive benefits across species that stands in contrast to the definition of prestige as the ability to bestow benefits (Thomsen, Reference Thomsen2020)— solicited no such preference. Conversely, even preverbal infants predict that others will join a more formidable, coordinated coalition (Fonn et al., Reference Fonn, Zahl, Kristensen and Thomsen2025), and 14-18-month-olds prefer and help the highest resource-holding individuals (Eason et al., Reference Eason, Enright, Weng, Horton, Sitch and Sommerville2024).

This is not to say that toddlers don’t also recognize authoritative, consensual instantiations of social hierarchy by dedicated cues. In fact, being bowed before—but not conferring benefits, receiving tribute, imposing a cost, relative size, nor coordinated mutual movements—is a sufficient cue for Norwegian toddlers to predict that others will continue to follow an agent’s directions in her absence (Margoni & Thomsen, Reference Margoni and Thomsen2024; modifying Margoni, Baillargeon, & Surian, Reference Margoni, Baillargeon and Surian2018’s paradigm which Thomas also suggests may show representations for caregivers). That was the case even though Norwegian toddlers have unlikely seen anyone bow, certainly not before their caregiver.

This points to the potency of evolved, core cues for predicting how relational coordination unfolds. Any particular social relationships are likely structurated (Giddens, Reference Giddens1984) from a learned history of different relational interactions, represented as summary network structures reflecting cross-species affordances (e.g., close cohesion, vertical differentiation). Relational core cognition makes this socializing learning possible by specifying a coordinative social grammar grounded in critical, adaptive cross-species relationships (e.g., sharing bodily fluids/kin solidarity; relative formidability/rank), but unlikely depends on aspects that vary across ecologies, such as how long concrete interpersonal relationships endure.