DOI: 10.5061/dryad.rfj6q57dh
title: Girls in early childhood increase food returns of nursing women during subsistence activities of the BaYaka in the Republic of Congo

description: Nursing mothers face an energetic trade-off between infant care and work.
 Under pooled energy budgets, this trade-off can be reduced by assistance
 in food acquisition and infant care tasks from non-maternal caregivers.
 Across cultures, children also often provide infant care. Yet the question
 of who helps nursing mothers during foraging has been understudied,
 especially the role of children. Using focal follow data from 140
 subsistence expeditions by BaYaka women in the Republic of Congo, we
 investigated how potential support from caregivers increased mothers’
 foraging productivity. We found that the number of girls in early
 childhood (ages 4–7) in subsistence groups increased food returns of
 nursing women with infants (kcal collected per minute). This effect was
 stronger than that of other adult women, and older girls in middle
 childhood (ages 8–13) and adolescence (ages 14–19). Child helpers were not
 necessarily genetically related to nursing women. Our results suggest that
 it is young girls who provide infant care while nursing mothers are
 acquiring food – by holding, monitoring, and playing with infants– and,
 thus, that they also contribute to the energy pool of the community during
 women’s subsistence activities. Our study highlights the critical role of
 children as caregivers from early childhood.
description: During a total of 230 observation days, we
 recorded the time when focal women began and finished foraging-related
 behaviors such as collecting nuts, digging wild yams, fishing, or hunting.
 From these data sets, the collection duration of each food item was
 calculated. We recorded the presence or absence of the focal women's
 nursing infants for each expedition. During focal follows, we continuously
 recorded expedition group composition and identified each individual in
 the group. When focal women returned to camp at the end of expeditions, we
 measured the wet weight of the edible part of the collected items in the
 women’s basket with a scale before the food was shared or cooked. We were
 able to weigh collected food items from 140 expeditions by nursing mothers
 before the food was distributed or processed. We were unable to weigh food
 items that were cooked and consumed on-site in the forest during
 expeditions, such as a part of a fish, caterpillars, or animals that were
 caught. From 140 expeditions, we were able to weigh 223 food items,
 categorized into animals (one species), fish (multiple species), nuts
 (five species), wild yams (five species), caterpillars (four species),
 mushrooms (five species), leaves (three species), and crops (seven
 species), indicating that BaYaka women collected more than one food item
 per expedition on average (ranging from one to four food items). Species
 of collected food items were identified with the help of botanists from
 the Herbarium at the Institute de Recherche en Sciences Exactes et
 Naturelles (IRSEN) in Brazzaville in the Republic of the Congo. After
 identifying food item species, we calculated the energetic calories of
 each food item collected in a day by multiplying the total wet weight of
 the edible part of a food item in a focal woman’s basket by the reported
 value of energetic calories per gram. We calculated food returns per
 collection duration by dividing the total energetic calories of a food
 item collected on an expedition by the total collection duration for that
 food item across the expedition in minutes (kcal/min). Collection duration
 was defined as working time in minutes from searching to food acquisition,
 which varied depending on food types: the total duration of 1) searching
 and picking caterpillars, mushrooms, and leaves, 2) building dams,
 scooping water, searching, and catching fish, 3) chasing, making holes on
 tree logs, and killing porcupines, 4) digging wild yams, 5) picking and
 cracking nuts, and 6) digging and collecting crops, such as cassava, taro,
 and maize. These six food types were included in the statistical models as
 random variables to account for possibly different effects of food
 items.
description: R