[grain of salt; a lot of armchair anthropology takes place in cultural evolution work. However, it is food for thought and a good reminder about the traditional WEIRD focus -Ken]
Going well back into our evolutionary history, humans have confronted the need to think about space in a variety of ways. Like other animals, human spatial navigation and memory present crucial cognitive challenges that have been linked to a variety of cognitive abilities, and human foragers have long needed to navigate through space and remember the details of their home ranges to avoid predation, find mates, and remember the location of objects or past events (Milton, 1988; Powell & Mitchell, 2012). Some of the most commonly studied spatial cognitive abilities include (1) spatial memory and navigation (which allows us to store and retrieve information about our surroundings, remember where objects are located, or where an event took place), (2) spatial perspective-taking (how objects in the environment are oriented in relation to another), and (3) mental rotation (the ability to imagine how an object that has been seen from one perspective would look if it were rotated in space or viewed from the new perspective). Decades of research have explored the degree to which these cognitive features are products of innately available representations (R. F. Wang & Spelke, 2002), how basic spatial processes interact with the symbolic world (Stokes, 2018), and what the role of individual differences is (Hegarty & Waller, 2005; Proulx et al., 2016).
Though spatial reasoning and associated cognitive abilities, such as spatial memory and mentalizing, improve throughout children’s development (Hart & Moore, 1973; Vasilyeva & Lourenco, 2012), there remain substantial performance gaps within and across populations that remain largely unexplained. For example, in an investigation of navigational ability between two WEIRD populations in Padua, Italy and Salt Lake City, Utah, USA, Barhorst-Cates et al. (2021), found that adults in Padua, who have substantially lower pointing error within their own city when compared to Utahans, were no more accurate at pointing to familiar distant targets outside their cities >10 km away than participants in Utah (~37° error).
Compare these WEIRD populations to traditional societies in Africa and Amazonia. In Amazonia, foragerhorticulturalists—the Tsimane—in Bolivia were asked to point from their home village to distant communities over 60 km away that are only accessible by canoe, traveling along a sinuous Amazonian tributary. Here, Tsimane adults average just 20 degrees of error (Davis et al., in press) and children average only ~40° pointing error (Davis & Cashdan, 2019). On the other side of the globe, in the arid regions of Nambia, Twa pastoralist-forager children (M = 11.6 years old, SD = 3.4 years) point to distant locations up to 90km away with considerable accuracy, averaging only 20° error (Davis et al., 2021), which is on par with adults in their communities and Tsimane adults, but is twice as accurate as the navigationally-challenged adults sampled in Padua and Salt Lake.
Though considerable prior work has aimed to identify and relate individual differences, surprisingly little work has focused on the characteristics of a navigator’s home environment, as well as on the cultural and daily navigational requirements, as an explanation for why individual differences may be observed. However, a few classic studies, along with a wide range of recent evidence from the Spatial Cognition and Navigation (SCAN) lab have demonstrated how local environments, economic demands and particular ecologies, and social norms and cultural institutions shape human’s spatial cognitive abilities (Barhorst-Cates et al., 2021; Cashdan et al., 2016; Crittenden et al., 2021; Davis & Cashdan, 2019). First, in the Padua and Salt Lake City study, Barhorst-Cates et al. (2021) found through interviews focused on daily activities and city mapping that the greatest influence on navigation strategies and accuracy between the two WEIRD populations was home environmental experiences. Padua adults, who live in a winding city filled with bridged moats and arcaded streets, were twice as accurate when pointing to within city targets when compared to Americans in Salt Lake City, who live on a metropolitan grid with few proximal cues but some distinct distal geological markers. The study further suggests that mode of travel and street network entropy may further improve or inhibit the development of navigational skills. This conclusion is further supported among the Tsimane and Twa. Among the Tsimane, labor demands require navigating dense tropical canopies with frequent cloud coverage that obscures distal cues. Though there are ecological risks, children are given considerable latitude to explore without adult supervision and are expected to contribute to household labor (Davis & Cashdan, 2019). Likewise, among the Twa, men and boys have historically traveled long distances to find grazing lands and water for their herds while women foraged nearby for medicinal and edible plants.
Similar links between ecology, social norms, and navigational ability have been identified in other studies among non-WEIRD children. For example, among the Mbendjele BaYaka in the Republic of Congo, children spend considerable time in work and play away from home beginning at an early age (Lew-Levy et al., 2020), and on a similar pointing task their navigational error was found to be as low as 7° (Jang et al., 2019). Likewise, in a seminal study among Alaskan school children (Kleinfeld, 1971), children of native Alaskan descent demonstrated far greater visual spatial memory than their Europeandescent peers. Building on earlier findings from Berry (1966), Kleinfeld attributed the differences in the two populations to the freedom to explore granted to children in Inuit populations. While children from both the Tsimane of Bolivia and Twa of Namibia performed well on tasks of spatial memory and navigation, they also showed highly developed spatial perspective taking skills, with only around 66° error when asked to imagine that they were in a known location far way and navigate from that mentalized location to a third target location. Compared to the Tsimane and Twe, studies in WEIRD populations suggest lower overall performance on spatial perspective taking (Vander Heyden et al., 2017), as well as large intra-population differences, which may in part be culturally influenced (Tarampi et al., 2016).
Given the role that ecology and socialization practices play on navigational and pointing ability, it is critical to reassess how some previously assumed genetic differences may be amplified by, or even the product of, social norms or cultural institutions. Sex differences have long been a focus of spatial cognitive research in WEIRD populations (Linn & Petersen, 1985; Voyer et al., 1995). Many studies report that men (compared to women) learn spatial environments faster and can recall routes with fewer errors (Coluccia & Louse, 2004; Galea & Kimura, 1993). Overall, sex differences in mental rotation remains among the most widely studied spatial skills that favor men (Voyer et al., 1995). And, although there is still some debate about the age that differences in spatial abilities are first observed; most WEIRD studies suggest that they emerge during middle childhood, around 9 or 10 years old (Neuburger et al., 2011). Given the consistency of these observed differences, evolutionary hypotheses have been proposed to explain why biological sex differences in spatial ability might exist (Geary, 2010). These hypotheses focus on the benefits males gain from meeting various navigational challenges, including mate seeking (Gaulin et al., 1990; Geary, 1995; Jones et al., 2003) or the emergence of the sexual division of labor in humans during the Pleistocene (Silverman et al., 2007).
Consistent with these arguments, it has been observed in both WEIRD societies (Hart, 1979; Matthews, 1987) and small-scale societies (Whiting & Edwards, 1992) that children first demonstrate significant sex differences in range size during middle childhood, when they begin participating in sex specific tasks and start spending more time with same-sex peers. These differences are argued to increase after adolescence, when boys enter their mate seeking years (Miner et al., 2014). For example, Vashro and colleagues (2016; 2015) found that among Twa pastoralists the average daily range size for Twa men was greater than that of Twa women. They also demonstrated that men had (1) lower average error on a navigational pointing task compared to women and (2) greater accuracy on a mental rotation task. Supporting an evolutionary account, Twa men with larger ranges were also found to have fathered more children by more women—they had higher fitness.
However, sex differences in navigational cognition don’t always emerge. In East Africa, sex differences in navigational abilities were not found among participants still living a traditional foraging lifestyle; instead, they only arose among participants from communities located closer to the market towns, where people tended to be less mobile and had smaller range sizes (Cashdan et al., 2012). Likewise, among Tsimane adults, where men and women both travel far for food, sex differences in navigational ability were not observed (Trumble et al., 2015). Instead, Tsimane’s daily mobility, wayfinding/pointing error, and mental rotation were related to differences in age, participation in the wage labor market and more years of formal education (Davis et al., in press). This raises questions about the role mobility patterns, market exposure, and formal schooling play in spatial cognitive development.
Illustrating the power of institutions to have unintended cognitive consequences, consider the impact of boarding schools for the Twa, where sex differences have been consistently observed among adult men and women (as mentioned above). When both boys and girls began traveling on foot weekly to government funded boarding schools, they demonstrated precocious navigational skills and no sex differences with increased mobility. Notably, boys and girls outperformed most adult women who had not had access to formal schooling growing up and whose mobility has been traditionally constrained by childcare and domestic work close to camp (Davis et al., 2021). In contrast, among tropical foragerhorticulturalists, where mobility patterns vary by age but not gender, children who spent more time attending local village schools traveled less than their peers and performed worse on navigational tasks (Davis & Cashdan, 2019), though they were still precocious compared to children in WEIRD societies.
Additionally, children in both populations showed higher performance on tasks of mental rotation (the ability to imagine what an object would look like if it were rotated about its axis) with more formal schooling. Children even outperformed their parents and other adults in their community with less schooling as early as 7 years old (Davis et al., in press). Altogether, this cross-cultural evidence suggests that early childhood environments, including the cultural institutions they’re exposed to, play a crucial role in the development of spatial cognitive abilities. Broadly, schooling improves some cognitive abilities while eroding others.
The upshot is that a narrow focus on WEIRD participants has resulted in a distorted picture of our species’ navigational cognition that can be seen in adult cognitive phenotypes, developmental patterns and apparent sex differences. An inclination to generalize from WEIRD people to “humans” persists among developmental psychologists and cognitive scientists despite a long history of such studies, stretching back into the 1960s.
_A Cultural Species and its Cognitive Phenotypes_