title: Cooperative breeding and maternal energy expenditure among Aka foragers.
abstract: OBJECTIVE
  Previous research among foragers and theory suggests that nonmaternal caregivers offer essential assistance, which supports female reproduction and the costs associated with lengthy child development. Mothers' face trade-offs in energy allocation between work and childcare, particularly when mothers have an infant. These trade-offs likely have crucial impacts on the pace of reproduction and child health. Caregivers can help mothers with childcare or they can reduce a mother's nonchildcare workload. If caregivers assist mothers by substituting childcare, then maternal energy expenditure (EE) in other work activities should increase. If caregivers assist mothers by substituting labor, then maternal EE in work activities should decrease when caregivers are present.
  
  
  METHODS
  Utilizing detailed, quantitative behavioral observations and EE data, we test these propositions with data from 28 Aka forager mothers with children <35 months old. We isolate paternal, grandmaternal, and other caregiver effects on maternal EE and childcare in multivariate analyses.
  
  
  RESULTS
  Our results show that caregivers (largely grandmothers) significantly reduce mothers' work EE by as much 216 kcal across a 9-hour observation period, while fathers and juveniles appear to increase maternal EE. Direct childcare from grandmothers decreases maternal direct care by about one-to-one indicating a labor substitution. Direct childcare from fathers decreases maternal care by almost 4 to 1, resulting in a net reduction of total direct care from all caregivers.
  
  
  CONCLUSIONS
  Our results indicate that there are multiple pathways by which helpers offset maternal work/childcare trade-offs.
authors.affiliation: Department of Anthropology, Washington State University, Pullman, Washington 99164-4910, USA. cmeehan@wsu.edu
authors.forename: Courtney L
authors.initials: CL
authors.lastname: Meehan
authors.forename: Robert
authors.initials: R
authors.lastname: Quinlan
authors.forename: Courtney D
authors.initials: CD
authors.lastname: Malcom
mesh_terms: D000293:Adolescent; D000328:Adult; D001947:Breeding; D002488:Central African Republic; D002648:Child; D002675:Child, Preschool; D003299:Cooperative Behavior; D004734:Energy Metabolism; D005220:Fathers; D005260:Female; D006379:Helping Behavior; D006801:Humans; D007223:Infant; D008297:Male; D008425:Maternal Behavior / Q000502:physiology*; D009034:Mother-Child Relations; D009035:Mothers; D016487:Parenting; D014937:Work / Q000502:physiology*; D055815:Young Adult