Lew-Levy and Amir make a convincing case, with admirable depth and breadth, that children’s peer groups contribute to cultural adaptation (see also, Hirschfeld, Reference Hirschfeld2002). This commentary seeks to qualify that argument, starting with what would otherwise be a minor quibble: although the authors do not say so explicitly, they suggest that cultural-evolution scholars claim that adults, and not children, drive cultural adaptation. A more apt description would be that children have mostly been ignored, with adult samples serving as an unmarked standard by which to generalize about people, and with few explicit claims one way or the other about the relative contribution of children. This is not just an observation about cultural-evolution scholarship, but about most cultural research (Hirschfeld, Reference Hirschfeld2002), and perhaps about the social and behavioral sciences more broadly. The term “unmarked” borrows from the linguistic conception of unmarked grammatical forms, such as the (now more marked) use of the masculine “he” or “man” to refer to the gender-neutral broader categories “he or she” or “human,” respectively (Irvine & Gal, Reference Irvine and Gal2000; Lakoff, Reference Lakoff1973). Adults are unmarked in the sense that they are treated as natural, normal, or representative examples of a broader category (people).

As many cultural psychologists have noted (perhaps most compellingly Arnett, Reference Arnett2008, and Henrich, Heine, & Norenzayan, Reference Henrich, Heine and Norenzayan2010), the problem of unmarked social categories goes beyond just cultural research to non-cultural work seeking to make generalizations about human psychology. Similar concerns have been raised in other fields, such as education (Medin & Bang, Reference Medin and Bang2014) and biomedical science (e.g., Heiat, Gross, & Krumholz, Reference Heiat, Gross and Krumholz2002). Henrich and colleagues have referred to that unmarked group in psychological science as WEIRD (Western, Educated, Industrialized, Rich, Democratic), preferring that acronym because their evidence suggests WEIRD people are outliers, less representative than other cultural groups, despite their overrepresentation in sample populations. The compelling acronym notwithstanding, many other categories could have been selected: urban, English-speaking, Global North, etc. Hirschfeld’s (Reference Hirschfeld2002) work suggests that adults should be added to that list. Lew-Levy and Amir’s target article could have valuably added to that conversation.

A useful frame for this is the home-field disadvantage (Medin, Bennis, & Chandler, Reference Medin, Bennis and Chandler2010; Medin & Bang, Reference Medin and Bang2014), a paradoxical reference to the typical advantage enjoyed by home teams in sports, pointing to the often-unrecognized disadvantage stemming from researchers’ social distance from their sample populations. Home-field samples (e.g., American university students) are less marked, with researchers readily generalizing from them to people, while such generalizations from non-home-field samples (e.g., Inuit hunter-gatherers) would be immediately recognized as problematic. Social distance does not just depend on demographic similarity, it depends on any factors that may impact the familiarity of a social-cultural category. Majority, higher status, and starting-point groups tend to be less marked than minority, lower-status, or novel ones. Adults are a good example of a home-field group since researchers are adults (similarity), there are more adults than children (at least among WEIRD people), adults are higher status, and adults have been a long-time convenience sample for experimental research (starting point). The home-field disadvantage contributes to overgeneralization (e.g., from adults to people) and to overlooking important differences across social-cultural groups (e.g., children). But it also impacts methods and the interpretation of results. For example, stimuli originally designed for home-field samples, by virtue of their better fit, are more likely to result in publishable significance levels, one possible reason WEIRD samples tend to be outliers when those original, hypothesis-confirming stimuli are later used in cross-cultural research with non-WEIRD samples (Bennis & Medin, Reference Bennis and Medin2010).

Two examples help clarify why the home-field disadvantage is relevant to the target article. The first concerns the child-adult dichotomy itself. The emphasis on children as the neglected group blurs the extent to which age matters to whether and how children contribute to cultural adaptation. It also masks the extent to which adults also form distinct, age-relevant peer cultures (Neugarten, Moore, & Lowe, Reference Neugarten, Moore and Lowe1965), some of which are marked and neglected similarly to children. Consider one of Lew-Levy and Amir’s childhood category, adolescents (13- to 17-year-olds), an age range that would be classified as adult rather than child by many non-WEIRD cultures (see, e.g., Whiting & Whiting, Reference Whiting and Whiting1975). As such, that key demographic of overlooked children driving cultural adaptation could just as well have been framed as an example of overlooked adults. The elderly are another, unambiguously adult example (e.g., Heiat et al., Reference Heiat, Gross and Krumholz2002; North, Reference North, Gilbert, Fiske, Finkel and Mendes2025).

Second, there are innumerable social-cultural categories differing widely across cultures that are not defined by age but that nonetheless form peer cultures with different dynamics for cultural adaptation. Limiting the examples to just WEIRD cultures, research scientists, politicians, and tech entrepreneurs, for example, each form peer cultures that innovate and transmit culture differently. But non-home-field sub-cultural groups within WEIRD countries (e.g., minorities or lower-status groups) may asymmetrically contribute to cultural adaptation given their lower populations and status, specifically because their markedness promotes the formation of more coherent, self-contained, identity-based peer groups (Lamont & Molnár, Reference Lamont and Molnár2002). By the time such peer cultures’ innovations eventually “escape” their peer cultures, they may be more fully formed and impactful, having had time to evolve independently and enter mainstream culture as recognizably novel. For examples of this with minority and low-SES peer cultures with music, see Baraka (Reference Baraka2002) or Roy (Reference Roy2010), but parallel examples can be seen in minority and low-power groups’ influences on a broad range of domains from clothing styles, to cuisine, to vernacular.

In short, while any article can only do so much, and Lew-Levy and Amir’s piece does a great job highlighting the underappreciated role of children in cultural adaptation, it would have benefited by acknowledging that both adults and children are just examples (albeit good ones), the former of an unmarked group inappropriately used to generalize about cultural evolution, and the latter of a marked group, inappropriately overlooked. When reified as a privileged two categories driving cultural adaptation, they risk reinforcing the underappreciation of social-cultural diversity in what it means to be human.