Week 11 – Context and process in the cultural learning of techniques: the example of blade tool use among BaYaka forager children in the Republic of the Congo

This early draft was authored by Adam Boyette.

Introduction

Understanding the mechanisms through which humans reproduce cumulative culture within lifetimes and across generations is a major goal of research on human evolution (Boyd & Richerson, 2005; Dean et al., 2014; Laland, 2017; Tomasello, 1999). For this project, we have been called on to engage the specific question of how flexible techniques are reproduced given human cognitive affordances and constraints. One problem that arises in addressing this question from an evolutionary perspective is understanding how humans learn complex techniques with high fidelity while being cognitively prepared to apply such techniques flexibly to new challenges faced in novel environments (Boyd & Richerson, 1995; Enquist et al., 2007; Rogers, 1988). In this chapter, I approach this problem from the stance that cultural learning, including learning a variety of techniques, occurs throughout development in a social and ecological context (Gauvain, 2005b; Greenfield et al., 2003). I follow the work of others and argue that this learning context is best understood as a culturally constructed developmental niche (Flynn et al., 2013; Kendal, 2011; Sterelny, 2004; Stotz, 2010; Super & Harkness, 1986), that, for young human cultural learners, may already be populated by the material basis of learning and a variety of experienced, capable, and willing models to learn from. These features of children’s environments facilitate their acquisition of flexible techniques. I begin by reviewing the theoretical and empirical foundations for this perspective before presenting a case study of non-hunting blade tool use throughout childhood among the BaYaka foragers of the Congo Basin.

Culturally constructed contexts of learning

Researchers across several fields recognize the importance of children’s environments in shaping their development, including how learning occurs (Kendal, 2011). Furthermore, through the course of learning individuals also can guide the (re)construction of the environments in which they learned (Flynn et al., 2013). For example, proponents of cultural niche construction argue that the human capacity for and reliance on cumulative culture evolved in concert with a tendency for “epistemic engineering” (Jeffares, 2012; Sterelny, 2004; Stotz, 2010). That is, embedded in the material culture humans produce is not only information about the environment but of human minds—what others know about the environment and how they act upon it. Such inferences were made possible through selection for abilities like perspective taking and goal sharing (Dean et al., 2014; Tomasello, 1999), which likely co-evolved also with changes in ancestral human social systems, which began to favor cooperative child-rearing and an extended childhood period (Burkart & van Schaik, 2016; Hill et al., 2009; Hrdy, 2009; Sterelny, 2012). As a result, young cultural learners would have been surrounded by a diversity of others from whom to learn. It is through these feedback processes that cultural niche construction, as a co-evolutionary process, can reduce the costs of social learning by buffering environmental changes – in other words, making aspects of cultural learners’ environment more regular, and yielding more opportunities to learn (Flynn et al., 2013; Fogarty & Creanza, 2017).

Learning blade tool use

Unfortunately, there are few empirical studies of cultural niche construction as such. In the following case study, I focus on children’s acquisition of non-hunting blade tool techniques to illustrate how the processes of cultural niche construction can facilitate learning. I focus on non-hunting blades for several reasons. Hunting tools and the techniques involved in their use are, arguably, not as flexible as the use of other types of blade tools, as they have been crafted for more specific purposes (e.g. the pursuit of specific types of game in specific ecologies). Additionally, hunting techniques are also typically learned later in life, and not necessarily mastered until the third decade of life (Koster et al., 2020). Furthermore, hunting techniques are typically learned by males, with young male foragers already showing a greater interest in hunting than females from early childhood, and adults endorsing this gendered division of activity interest (which supports the gendered division of labor) by giving males toy hunting tools and girls toy foraging tools (Lew-Levy et al., 2018) [1]. Finally, non-hunting blade tools are perhaps more evolutionarily relevant, since it is likely that early hominid stone tools were general purpose and not used for the types of pursuit hunting common today (Plummer, 2004), and thus a focus on the acquisition of non-hunting techniques by children is a better model of how such cultural learning may have been involved in the evolution of human tool use.

Importantly, I am focusing on my analysis simply on the availability of non-hunting blade tools (hereafter ‘blade tools’) and the opportunities to observe, be taught, and to practice their use. In other words, I do not examine blade tool construction. Undoubtedly, the construction and use of blade tools for a variety of subsistence tasks was a fundamental cultural adaptation for our species (McBrearty & Brooks, 2000; Morgan et al., 2015; Stout, 2011), and of course remains so today. However, in the region where I work, as in much of the world today, blades are not locally made but largely imported. Among the BaYaka, whom are the subject of this case study, there are those with knowledge of iron forging who can craft ax heads and knife blades, but these tools typically come from non-local sources and are acquired through trade. Thus, the vast majority of other blades are made of steel and are imported and their construction is not part of the daily learning experiences of interest here. It should be noted, though, that novice tool-makers’ presence near to and participation in the construction of blade tools is inferred from sites across the world and deep into human evolutionary history (e.g. Grimm, 2000; Takakura, 2013). While we cannot be sure of the ages of the novice tool makers, we can infer that with the emergence of the “domestic space”—a central place for food sharing and cooperative child rearing—juveniles were at least present to observe various uses of stone tools beginning as early as 450 kya (Kuhn & Stiner, 2019). Today, while the use of blade tools by children tends to be discouraged in families from modern, large-scale, industrial and post-industrial societies, this is not the case across contemporary small-scale, subsistence societies, where children are often integrated into the economy from early ages and begin to manipulate knives, machetes, and other tools long before they can productively use them (Lancy, 2016). This is the context to which I now turn

Case Study: Aka children’s experience with blade tools

The BaYaka are a group of several populations of tropical forest foragers living across the Congo Basin (Lewis, 2002). “BaYaka” is a general term for several groups including those referred to in publications as the Aka (Bahuchet, 1985; Boyette, 2016; Boyette & Lew-Levy, 2019; B. L. Hewlett, 2005; B. S. Hewlett, 1991), Mbendjele (Lewis, 2002), BaYaka (Boyette et al., 2020; Lew-Levy et al., 2020) or Mbendjele-BaYaka (Jang et al., 2019; Sonoda et al., 2018) who live in the northern Republic of the Congo and southwestern Central African Republic. Here, I’ll be drawing on qualitative and quantitative data from two BaYaka populations I have worked with: The Aka of the Lobaye Province in the Central African Republic, and the BaYaka of the Motaba river region in the Likuouala Province of the Republic of the Congo. In my analysis, I’ll use the term “BaYaka” to refer to these two populations, as the data I will draw from can be reasonably generalized to both, who share the same language and culture, with some regional variation, and intermarry.

Aka cultural niche construction

As noted above, the processes of cultural niche construction can support cultural learning through lowering costs to learning, such as making it easier to find models to observe, teachers to teach, or opportunities to practice. In this way, BaYaka settlements are highly supportive of blade tool use learning. Hewlett et al. (2019) describe BaYaka spaces and spatial use as intimate, even in comparison to a general trend towards close living among foragers as compared to food producing peoples. For instance, Aka typically live in a one-room dwelling, 4.8-square-meters in size, accommodating an average of 3.1 people, giving about 1-square-meter of space per person on average. Importantly, these houses are on average placed within 4.3 meters of nearest neighbors, and very little is done inside the dwellings other than sleeping, with much of life being conducted outdoors in sight of all other members of the community. BaYaka settlements are generally of two types: smaller forest settlements with traditional, mongoulou domed houses; and village settlements with larger, mud-brick houses. However, the public nature of most activities is consistent across both types of settlements, and children in particular are never barred from entering any dwelling, no matter who is currently sleeping therein. Hewlett et al. (2019) find consistencies between Aka spatial use patterns and cultural models of social relationships—especially between parents and children, and between marital partners—as valuing physical closeness among social partners. Anecdotally, when joining a group of people sitting together, BaYaka people will often sit so as to be in physical contact with another, no matter how much space is available.

These spatial aspects of cultural niche construction are consistent with a larger emphasis on sharing that is common to mobile foraging peoples. Construed widely, this sharing includes not only food, but also other material resources, time, and knowledge (Lavi & Friesem, 2019). Here, I will emphasize in particular that these spaces facilitate both sharing of material bases for learning techniques, such as blade tool use, as well as the knowledge and skills embodied in others. In terms of the former, as noted, most work is done outside of the house, and most household objects are also stored outside. Blades are prominent among these objects. For example, a brief survey of items used in food preparation of a random sample of 14 Aka households at a village settlement in CAR in 2012 shows that most households had at least 2 knives or machetes, making these blade tools the second most numerous of 12 items named, after plates and tied with the number of cooking pots per household (Table 1). Note that the traditional BaYaka ax, the djumbi, was not counted among these items, nor were, for example, razor blades, or gileti, which are commonly in circulation, though disposed of after one or two uses. Thus, this table reflects a bare minimum of children’s opportunities to observe and interact with blades throughout daily life.

	object	sum	mean
1	plate	32	3.56
2	cooking pot	30	2.31
3	knife/machete	30	2.31
4	spoon	21	1.62
5	jerry can	14	1.56
6	sieve	9	1.12
7	basin	8	1.60
8	bucket	4	1.33
9	mortar + pestle	3	1.00
10	cup	1	1.00
11	cutting board	1	1.00
12	stirring stick	1	1.00

Blade tools and early childhood

In terms of the specific ways BaYaka cultural niche construction enhances social and individual learning opportunities, I will now discuss how such knowledge and skill sharing occurs across childhood, to gradually (re)produce technically competent members of the community. In general, respect for autonomy is a core cultural model—or foundational cultural schema (Boyette, 2019; B. S. Hewlett et al., 2011)—among the BaYaka, and, in this is true for all individuals regardless of age. As such, BaYaka parenting is considered indulgent. For instance, infants nurse on demand, and are responded to immediately when distressed by any nearby caregiver, typically but not always a parent, who nurses or sooths them (B. S. Hewlett et al., 1998). One aspect of the autonomy granted young children is that they are permitted to engage with any objects they find around camp, including blade tools. Parents and other caretakers are not being negligent when allowing children access to these tools. Indeed, children being cut or cutting others with blades is a common concern among BaYaka parents (Boyette and Cebioğlu, forthcoming). However, they indulge children’s autonomous interest and even encourage interaction with these tools. For example, when the hafts of knives used in food preparation break, these now “useless” blades are given to young children to play with. In the parlance of social learning, this is a classic example of opportunity scaffolding. In a sample of 10 Aka infants aged 12-14 months, Hewlett and Roulette (2016) observed opportunity scaffolding nearly once every hour on average in their sample of 10 hours of infant-focused video. While they did not code the objects used, knives were prominent across the range of teaching behaviors they observed, including instances of natural pedagogy, moving a child’s body, and demonstration. These observations are not surprising given the spatial prominence of these blades and their regular use by people across a wide range of everyday tasks.

Blade tools from middle-childhood to adolescence

Until around the age of 7-years-old, BaYaka children typically stay near to the settlement, typically under the casual supervision of at least one elder who remains in camp if others are away. As BaYaka children transition from toddlerhood and weaning into middle childhood, across the ages of 4-6-years-old, children move to spending their time with a multi-age, all child play group who may venture into the forest to play or autonomously forage (Boyette, 2016; B. S. Hewlett et al., 2011; Lew-Levy et al., 2020). This context offers significant opportunities for social learning and individual practice with blade tools through scaffolded interactions with other, slightly older children (Gauvain, 2005a; Lew-Levy et al., 2020). As a quantitative demonstration of such opportunities, I present data collected during my study of Aka children’s time allocation and social learning in CAR in 2010. More details of the methods used to collect these data can be found elsewhere (Boyette, 2016; Boyette & Hewlett, 2017; Lew-Levy & Boyette, 2018). Briefly, I used systematic behavior coding during focal follows of 50 individual Aka children from the ages of 4 through 17 years old, with a mean of 238.62 observations per child. These children were from 8 different forest settlements. While I did not specifically set out to record blade use, early during my observations, I started noting such use in the margins of my data-sheets early during collection, as I was struck by how capable children were with machetes, axes, and knives. These notes are not as systematic as the behavioral coding that was the focus of my study, but they do reflect a bare minimum estimate of the presence of blade tools in children’s everyday contexts across my observations.

To quantify blade tool use in these data, I performed a search of the notes I kept intermittently in a column of my minute-by-minute data coding sheets. Specifically, I searched for the following text strings: “chop”, “cut”, “dig”, “kni”, “machete”, “yebe”, “ax”, “jumbi”, and “blade”. Note that yebe is the word for “knife”, djumbi is the traditional ax, and that machetes (and knives during children’s play) are often used for digging. All notes that were found through the text search were then reviewed and irrelevant observations were excluded, (e.g. if “cut” was in the word “cute”; or the note did not reference the on-going activity). Overall, one or more of these text strings was noted in 74 observations spread across 26 of the 50 children (16 female, 10 male), with an average of 2.8 observations per child. These included 22 mentions of “chop”, 15 of “dig”, 17 of “cut”, and 25 where a blade was mentioned (5 observations had mentions of a blade and an action, and these were counted as a single observation). It is also important to note that I included in these data mentions of blade use by the child or by someone with the child. For the sake of my argument, this distinction is not critical, as again, these data were not systematically collected and thus provide only a reasonable, minimal account of the opportunities to learn blade tool techniques in these children’s lives.

First, while not noted that frequently overall, blades were noted persistently throughout my observations. For example, blade use was noted in focal follows of children from 7 of the 8 Aka forest communities, or “camps”, in which I lived. Additionally, there was no obvious concentration of observations in any one camp, with 10.6 observations noted per camp. Furthermore, as plotted in Figure 1a, these observations were not concentrated at any particular time during the study period, which extended from April until September (the gap in time in Figure 1a during the time I worked with Ngandu farmer children, who also used blade tools but are excluded from the current analysis); nor was blade use noted among children of any one age (Figure 1b); and observations were consistently distributed across boys and girls of different ages and throughout the study period, although girls use of the tools was twice as frequently noted, 50 times for girls versus 24 times for boys.

Second, blade use was observed across a broad range of children’s activities. In fact, as can be seen in Table 2, it was not observed in only the three least frequently observed activities, Childcare, Music, and Hygiene. Notably, blades were over-represented in three activities relative to how frequent those activities were observed in the full dataset. In particular, while Work-themed pretense play was observed in only 4.7 percent of all observations, 29.7 percent of the observations with blades were during this activity. This reflects 3.9 percent of all observations of work-themed pretense play, which was coded when a child re-enacted traditional subsistence activities, such as digging for wild yams, making a play house, or chopping trees (Lew-Levy & Boyette, 2018). While less frequently noted across children’s activities, blades were also noted during child-initiated work and work at a higher frequency than was observed in the full dataset. The former was coded when the focal child was involved in subsistence work without involvement from adults, while the latter was coded when the child worked with an adult or the subsistence activity was initiated by an adult (whether or not the adult and child worked together at the task).

Activity	Percent of full dataset	Percent of blade-use dataset	Percent of observations of activity in which blade tool use was observed1
Work-themed pretense play	4.70	29.70	3.90
Child-initiated work	10.30	17.60	1.06
Work	7.50	10.80	0.90
Other	4.80	4.10	0.52
Rest	27.70	20.30	0.45
Play	20.90	12.20	0.36
Travel	5.50	2.70	0.31
Eats	5.10	1.40	0.17
Visit	9.60	1.40	0.09
Childcare	1.30	NA	NA
Music	1.40	NA	NA
Hygiene	1.10	NA	NA

Third, I also examined the presence of adults and the settings in which blade use was observed. During my observations, I coded whether mother, father, both parents, parents and other adults, or no adults were within visual range of the focal child. When blade tool use was observed, 66% of the time the focal child was in sight of parents and others; 9% of the time either the children’s mother or both parents were present; and 24% of the time no adults were in sight of the child. In terms of settings, the observations of blade tool use were fairly similar in their distribution to where children generally spent their time. In particular, 68% of the observations were in the domestic space of the forest camp, whereas 20% were in the forest. The other 12% were either in or near gardens or at the forest camp of an Ngandu farmer family with whom they spent time.

General Discussion

The results of my analysis demonstrate a minimum measure of BaYaka children’s experience with blade tools during their daily lives. In brief, every BaYaka household owns multiple blade tools, which young children observe in use every day and seek to interact with. While parents worry about accidental cuts, they still begin to scaffold children’s use of blades early, through opportunity scaffolding and occasional teaching. This in and of itself demonstrates that parents see the benefits of early acquisition of blade techniques as outweighing any costs. As children grow, blades remain present when children are in the domestic space and travel with them as they go into the forest to forage or play, whether adults are present or not. These tools are used across most contexts of daily life, especially during work-themed pretense play as well as legitimate productive subsistence work. Previous work has shown that BaYaka children work more and play less from early childhood through adolescence (Boyette, 2016), including play that is imitation of work (Lew-Levy & Boyette, 2018). We have interpreted this pattern to indicate that play serves as a context in which children learn so that they increasingly become legitimate participants in daily economic life. The flexible techniques associated with blade tool use are critical to this learning. Through the feedback processes of cultural niche construction, BaYaka children will inevitably learn how to use knives, axes, machetes, and razor blades to chop wood, clear the ground around camp, build a house, make baskets and mats, crack nuts, peel manioc, skin a duiker, divide meat, cut edible leaves, dig for wild yams, style hair, cut fingernails, and more.

Earlier eco-cultural theories of child development emphasized the how settings and the company children keep shape children’s cultural learning opportunities (Weisner, 1984; Whiting, 1963; Whiting & Edwards, 1988). The cultural niche construction perspective adds that these regularities of children’s developmental context can serve to support adaptation to particular social and ecological environments. For the BaYaka, the distributed nature of expertise in blade tool use likely contributes to the overall high level of coordination of subsistence activities and cooperation in general that characterizes their society. Hewlett and colleagues emphasize that for BaYaka children, their settings are open to free exploration and that the entire community is available to learn from such that few social roles or specific skills are hidden from young cultural learners (B. S. Hewlett, 2014; B. S. Hewlett et al., 2016). From infancy, responsive caregiving by many others and respect for autonomy to explore spaces and artifacts leads to security and trust and highly self-motivated learners, who see learning techniques as part of belonging to the group (Over, 2016). Such features of the BaYaka cultural niche enhance the cultural learning of everyday knowledge and skills through multiple learning processes and pathways throughout children’s development.

Of these processes, top-down-instruction in blade tool techniques does not appear to be as important as others. Multiple studies have demonstrated that teaching is an important part of BaYaka children’s daily lives (Boyette & Hewlett, 2017; B. S. Hewlett & Roulette, 2016; Lew-Levy et al., 2020). However, teaching is less common than observational learning (Boyette, 2016). The importance of observational learning is clear in the data on middle-childhood I present here. For instance, it is noteworthy that 20 percent of the observations were when children’s activities were coded as “Rest” (Table 2), when children were simply watching others use blades, or laying around fiddling with blades themselves. Such observations are then honed through individual learning by playing and working, as shown here by the disproportionate observations of blade use during these types of activities. Through this process, children become able to flexibly apply their skills across the wide range of subsistence tasks for which they are needed. Moreover, the openness of the BaYaka learning environment and diversity of others available to be observed leads to “concerted” or “many-to-one” cultural transmission (B. S. Hewlett & Cavalli-Sforza, 1986). This mode of cultural transmission, through which cultural learners learn from many other more experienced individuals, theoretically leads to low variation between individuals in the population and high conservation of skills across generations.

To conclude, I do not suggest the BaYaka cultural niche nor its effects on children’s learning are representative of other foraging groups, nor of past human societies per se. However, I do think there are aspects of their social structure and ecological adaptations that can permit some inferences about how similar contexts of cultural learning would support the gradual and inevitable acquisition of blade tool techniques during individual lifetimes and their reproduction across generations with high fidelity. In particular, with the co-evolution of the human family, cooperative childcare, and the domestic space of the hearth, which becomes the center of social activity and sharing well before the evolution of Homo sapiens (Kuhn & Stiner, 2019), the cultural niche construction perspective focuses the analytical lens on the opportunities afforded for the (re)production of at least some common, flexible techniques that have been critical to the evolution of human cumulative culture and cognition, such as the use of non-hunting blade tools.

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[1] Of course, this may also be an example of the co-evolution of biology (e.g. sexual-dimorphism in physiology, human mating and family systems) and culture (e.g. gender socialization) that is supported by cultural niche construction. However, such an analysis is outside the scope of this analysis.