We are grateful for the opportunity to comment on Ko & Neuberg’s (K&N) thoughtful target article, which promotes the concept of affordances as having a valuable role to play within human evolutionary theory. We agree that affordances are valuable here, and we will take the opportunity to provide some theoretical context. The notion of affordances was introduced by James J. Gibson (Reference Gibson1966, Reference Gibson1979), whom the authors acknowledge. Gibson’s aim, which the authors do not acknowledge, was to develop a novel theory of perception based on the direct pickup of structure in ambient information. Affordances are central to the ecological approach to psychology, a tradition that builds on Gibson’s work (Segundo-Ortin & Raja, Reference Segundo-Ortin and Raja2024). We are surprised that the authors do not engage with the extensive literature in the ecological psychology tradition. We believe that doing so would allow the authors to address several weaknesses in their proposal. We will focus on four key points.

(1) Affordances are perceivable. Affordances, if they are to structure behavior, must be perceived. The target article fails to address the question of how perception is achieved for any of the cited examples. Empirical work in ecological psychology has sought to identify the precise ecological information implicated in the control of a given behavior (Wagman, Reference Wagman, Wagman and Blau2020; Warren, Reference Warren2021). For example, to safely control braking, the driver can attend to the global rate of optic flow that specifies their current rate of deceleration (Fajen, Reference Fajen2005; Gotardi et al., Reference Gotardi, Van der Kamp, Navarro, Savelsbergh and Rodrigues2024). In the target article, K&N are interested in facts of a different order, such as the genetic relatedness of potential partners, the ratio of men to women in the local population, or the possibility of alloparenting. An individual can gain knowledge about all these things, but it is unclear exactly what is meant to count as the affordance in these cases, far less how those affordances could be cashed out perceptually in terms of ecological information (Segundo-Ortin & Heras-Escribano, Reference Segundo-Ortin and Heras-Escribano2024). The knowledge in these cases is of a peculiarly human sort: it requires abstract rational thinking. This brings us to our second point.

(2) Affordances are general to all animals. In his later life, Charles Darwin carried out a series of empirical studies on earthworms (Darwin, Reference Darwin1881). Among other things, he discovered that these creatures selectively and efficiently plug the openings to their burrows by dragging in leaves by the narrow end first. As noted by Ed Reed, this is an “example of how behavior is regulated by affordances” (Reed, Reference Reed1996, p. 21). If we accept Reed’s assessment, then we must conclude that affordances are prevalent across the animal kingdom (Wagman et al., Reference Wagman, Lozano, Covarrubias, Cabrera, Jiménez, Zepeda Riveros, Cabrera González, Camacho Candia and Camacho Gutiérrez2019). K&N’s primary examples – avoiding inbreeding, violent environments, and unfavorable sex ratios – are relevant to all sexually reproducing animals, not just humans. But remember that affordances can affect behavior only to the extent that the animal is able to perceive the affordance in question. Can non-human animals perceive genetic relatedness? Interestingly, recent evidence suggests that many non-human species do not in fact have mechanisms to avoid inbreeding (de Boer et al., Reference de Boer, Vega-Trejo, Kotrschal and Fitzpatrick2021; Pike, Cornwallis, & Griffin, Reference Pike, Cornwallis and Griffin2021). An important difference between humans and other animals is that we have symbolic culture, which enables us to conceive of the very notion of inbreeding and to create cultural taboos and customs against it. Apropos of which…

(3) Affordances are relative to individuals, but humans live in groups! The target article focuses on individuals’ “management” of resources, through measures such as “relocating [one’s] family to access kin support” or hanging out in “e.g., clubs or bars on Friday nights” to find potential partners. The focus on individual behavior obscures the ways that K&N’s examples presuppose communal infrastructure such as, say, the peculiarly human and historically contingent notion of a “Friday night.” By neglecting the communal and institutional dimensions of human behavior, K&N – perhaps inadvertently – sometimes couch socially rooted patterns as simple outcomes of human biology. For instance, persistent patterns of gender imbalance in parental and kin investment are linked to biological reproductive asymmetries such as the costs of gestation and genetic certainty. While such asymmetries exist, this focus neglects the contribution of social norms, cultural institutions, and economic structures in generating unequal caregiving responsibilities and obscures the fact that caregiving arrangements are amenable to cultural change and collective reform. More troubling still is K&N’s discussion of sexual violence. They describe male violence against women – particularly young women of reproductive age – as a strategy to control female sexuality for reproductive advantage. This framing threatens to naturalize gender-based harm by treating it as an adaptive reproductive behavior of heterosexual males. Moreover, it portrays individual solutions to violence, like threat “management” on the part of women, as desirable rather than highlighting the need for community-scale solutions that address its cultural, political, and institutional determinants (Chater & Loewenstein 2024).

Typically it is human communities, not individuals, that develop solutions to deal with genetic relatedness (marriage customs), physical violence (laws, punishments), and skewed sex ratios (government campaigns in many countries). Individual management of affordances alone cannot explain such community-scale mechanisms (Baggs, Reference Baggs2021; Heft, Reference Heft2001) which are explicitly negotiated and require human language and reasoning. Ultimately, a theory of affordances in humans must be accompanied by a theory of how children learn to become members of their community (Baggs & Chemero, Reference Baggs and Chemero2020; Chemero, Reference Chemeroforthcoming). This is a process that takes time…

(4) Affordances change continuously, not discretely, across development. K&N inform us that “[l]ittle is known […] about how human-environment interactions vary across the lifespan.” On the contrary, the study of development has been a key strand of the ecological program, from Eleanor Gibson’s classic studies of infants on the visual cliff (Gibson & Walk, Reference Gibson and Walk1960) and subsequent studies of infant and child learning (Adolph & Hoch, Reference Adolph and Hoch2019; Thelen & Smith, Reference Thelen and Smith1994) to work on skill acquisition (Silva et al., Reference Silva, Kiefer, Riley, Chemero and Cappuccio2019) and motor rehabilitation in adults (Silva & Schwab, Reference Silva and Schwab2024; Vaz et al., Reference Vaz, Silva, Mancini, Carello and Kinsella-Shaw2017). The target article discretizes human development around two life transitions: puberty and parenthood. In reality, the body continuously changes, and affordances therefore continuously change too. We invite the authors to explain how the affordance management framework deals with such continuous bodily changes.

Given these four points, we find that the authors are in danger of trying to reinvent several existing lines of research. There is an enormous published literature about affordance perception, and the target article would have benefited had K&N consulted it. We hope that the authors will use the works we cite here as guides into the literature on affordances.