Sex differences in daily activity intensity and energy expenditure and their relationship to cortisol among BaYaka foragers from the Congo Basin

Abstract

ObjectivesThe pooling of energetic resources and food sharing have been widely documented among hunter‐gatherer societies. Much less is known about how the energetic costs of daily activities are distributed across individuals in such groups, including between women and men. Moreover, the metabolic physiological correlates of those activities and costs are relatively understudied.Materials and methodsHere, we tracked physical activity, energy expenditure (EE), and cortisol production among Congo Basin BaYaka foragers engaged in a variety of daily subsistence activities (n = 37). Given its role in energy mobilization, we measured overall daily cortisol production and short‐term cortisol reactivity through saliva sampling; we measured physical activity levels and total EE via the wGT3X‐bt actigraph and heart rate monitor.ResultsWe found that there were no sex differences in likelihood of working in common activity locations (forest, garden, house). Across the day, women spent greater percentage time in moderate‐to‐vigorous physical activity (%MVPA) and had lower total EE than men. Females with higher EE (kCal/hr) produced greater cortisol throughout the day. Though not statistically significant, we also found that individuals with greater %MVPA had larger decreases in cortisol reactivity.DiscussionBaYaka women sustained higher levels of physical activity but incurred lower energetic costs than men, even after factoring in sex differences in body composition. Our findings suggest that the distribution of physical activity demands and costs are relevant to discussions regarding how labor is divided and community energy budgets take shape in such settings.

Gender differences in BaYaka forager sleep-wake patterns in forest and village contexts

“…Overall, women also exhibited less circadian fragmentation than men, and slightly stronger and more stable circadian rhythms. It is possible that, despite labor coordination between BaYaka men and women 20 , 35 , gender-differentiated work and social activities, particularly in the forest location, may drive gender differences in sleep expression and in circadian rhythms. Functional linear modelling analysis revealed that women had significantly higher activity levels than men, with a sharp rise in activity almost immediately after waking, which remained higher than men for the remainder of the day.…”

“…This may be linked to collaboration in subsistence activities. For example, in the BaYaka community surveyed here, Sarma et al 35 found important complementarities in men and women’s work—BaYaka men and women will work side-by-side in gardens, with men clearing plots and women planting. Unlike other societies where heightened gender distinctions in types and intensities of subsistence roles drive significant differences in day and nighttime activity between men and women 36 , it is possible that BaYaka sleep patterns are similar between men and women because of a less rigid gendered division of labor.…”

Sharing and caring: Testosterone, fathering, and generosity among BaYaka foragers of the Congo Basin

“…shaping children's proper socialization; caring for ill children). As we have described in prior work, fathers' indirect care (Provider) was much more highly valued among the Bondongo, compared to direct caregiving (Direct), and Bondongo fathers engaged in relatively little direct care, on average 43,44 . In the current analyses we only included Bondongo rankings for Provider and Dispute, as they could be compared to similar domains among the BaYaka.…”

“…In the Bondongo sample, all participating fathers in the current analyses (n = 16) ranked one another using the same procedure we outlined above for the BaYaka rankings. The Cronbach's alphas for these peer-rankings were 0.84 (Dispute) and 0.95 (Provider) 44 . The Bondongo men in the sample knew each other well, as most had grown up together and/or were related through kinship by various degrees.…”

“…BaYaka fathers also cosleep with their families, facilitating nighttime father-child proximity 43 . Compared to those parenting behaviors, BaYaka men, like many forager fathers elsewhere, also typically devote substantially more daytime hours to subsistence activities, such as hunting/fishing and collecting honey, to acquire resources for their families and for sharing in the broader community 30,33,35,44 . In some otherwise egalitarian settings, hunting ability/reputation is a pathway through which men gain social status, which has been linked to greater fitness 45 .…”