The authors note that, although children today “frequently teach their parents about new technology,” they “found little evidence for [children’s] peer cultures producing complex technological innovations.” The Homo material record exhibits a similar lack of evidence. If children were active agents in cultural adaptation, we would expect to see regular innovation in Homo tool industries. However, from H. erectus to H. Neanderthalensis to early H. sapiens, these industries are remarkable for their stability. The Acheulean industry lasted over a million years (Boyd & Silk, Reference Boyd and Silk2018), and the Neanderthals “show technological inertia in the development and use of lithic tools for 200,000 years” (Bocquet-Appel & Tuffreau, Reference Bocquet-Appel and Tuffreau2009:287). Similarly, in their exhaustive survey of the H. sapiens material record in Africa, McBrearty and Brooks conclude that the transition from Middle to Late Stone Age technology was gradual and that “both human anatomy and human behavior were intermittently transformed from an archaic to a more modern pattern over a period of more than 200,000 years” (Reference McBrearty and Brooks2000:458). The stability of these technologies suggests that, until relatively recently – most notably the “creative explosion” (Pfeiffer, Reference Pfeiffer1982) of Upper Paleolithic Europe – the human cultural pattern was predominantly one of conservation, not innovation.

The burst of innovation that coincided with the migration of anatomically modern humans (AMH) into Europe ∼45 kya is widely regarded as evidence of behavioral modernity and as an archaeological anomaly that begs explanation (e.g., Mithen, Reference Mithen1996; Powell, Shennan, & Thomas, Reference Powell, Shennan and Thomas2009). In other words, behavioral modernity is characterized as a pronounced diversification in cultural adaptation strategies and a departure from the preceding material record. Behavioral modernity is characterized by improved blade and burin technology, exploitation of novel raw materials, use of personal ornaments, complex art forms, symbolic notation systems, musical instruments, long-distance exchange networks, and improved missile technology (Mellars, Reference Mellars2005). Although research shows that many of these behaviors appeared 30,000–40,000 years earlier in Africa (in a more gradual, piecemeal fashion; McBrearty & Brooks, Reference McBrearty and Brooks2000; Mellars, Reference Mellars2005), they are nevertheless of relatively recent emergence, evinced only by AMH. In contrast, the extended human subadult period began evolving ∼2 mya, in conjunction with the dietary shift and associated brain expansion (Aiello & Wheeler, Reference Aiello and Wheeler1995; Kaplan et al., Reference Kaplan, Hill, Lancaster and Hurtado2000; Leonard, Robertson, & Snodgrass, Reference Leonard, Robertson and Snodgrass2007).

Thus, a logical place to look for evidence that children contributed to innovation is the Middle-Upper Paleolithic transition in Europe. Demographics played a key role in this shift. Compared to Neanderthals, AMH populations were larger (Powell et al., Reference Powell, Shennan and Thomas2009) and had a higher proportion of older adults (Caspari & Lee, Reference Caspari and Lee2004). Neanderthal populations may have been up to ten times smaller than those of their AMH contemporaries (Boyd & Silk, Reference Boyd and Silk2018:316), and few of their members survived to age 40 (Trinkaus, Reference Trinkaus2011) or even 30 (Caspari & Lee, Reference Caspari and Lee2004). Consequently, there were few individuals and little time in the lifespan for making and transmitting new discoveries (Bocquet-Appel & Degioanni, Reference Bocquet-Appel and Degioanni2013). In contrast, increased longevity and group size in H. sapiens exponentially increased opportunities for knowledge accumulation (including new discoveries) and intergenerational knowledge transfer. A striking conclusion follows: the spark that ignited the explosion of cumulative culture was grandparents, not children (Caspari, Reference Caspari2011).

These findings are supported by the modern hunter–gatherer ethnographic record. Cumulative culture depends heavily on the conservation of knowledge, which in turn depends on accurate transmission across generations (Palmer, Reference Palmer, O’Brien and Shennan2010; Scalise Sugiyama & Reilly, Reference Scalise Sugiyama and Reilly2023; Scalise Sugiyama, Reference Scalise Sugiyama2024). In hunter–gatherer and other traditional cultures, this task falls largely to older adults, who are widely regarded as the most knowledgeable members of the community and most proficient transmitters of cultural lore (e.g., Schniter et al., Reference Schniter, Gurven, Kaplan, Wilcox and Hooper2015). For example, “Younger Ju/’hoan people, when asked for stories, most often protest that they ‘have not grown old enough to have learned the things that old people know’” (Biesele, Reference Biesele1993:18). This is not false modesty: Biesele further observes that “in general their narrative abilities are less well formed” (Reference Biesele1993:19) than those of their elders. Similarly, “Older people in Aboriginal society are regarded as reserves of important knowledge concerning the Dreaming and the physical resources of the landscape. By virtue of their survival experience, older people in society are often considered to have immense spiritual power” (Clarke, Reference Clarke2003:49).

This appreciation of greater life experience and the power (i.e., autonomy) it confers manifests itself as an ethos of respect for elders. For example, Nunamiut and Tareumiut “children are accustomed to whisper in conversing with adults and to remain quiet. The child was expected to obey all older people, and fell into this regimen fairly readily” (Spencer, Reference Spencer1959:237). Similarly, the “first and chief duties that … [Ainu] children were taught were obedience to parents … and reverence for the old men of their village. They were to speak when spoken to, and at other times to be seen, but not heard. By no means were they allowed to interrupt their elders when engaged in conversation” (Batchelor, Reference Batchelor1892:109). These imperatives indicate that children were not regarded as fonts of useful knowledge and were not encouraged to explore new ways of doing things. Rather, forager education emphasized mastery of traditional teachings and technology. This is seen in the training of Nunamiut and Tareumiut hunters: when a boy’s voice changed, “he was permitted to share in hunting and whaling, not yet as a fully fledged participant, but as an observer and apprentice. This was considered to form a vital part of his education” (Spencer, Reference Spencer1959:241; my emphasis). Amid such restrictions, if children did indeed contribute to cultural adaptation, it was likely an uphill battle.

A striking feature of children’s culture is that its products mirror adult culture: foraging technologies, processing techniques, ecological knowledge, verbal skills, social norms, etc. Thus, like Baka play-trapping, which “combines recreational and educative purposes as it prepares budding trappers for adulthood” (Dounias, Reference Dounias2016:9), children’s peer culture can be seen as a set of play activities that teach them how to be “cultural” at a level of complexity compatible with their cognitive and anatomical limitations. I second the authors’ call for more targeted research on this topic.