title: Isotopic evidence of weaning in hunter-gatherers from the late holocene in Lake Salitroso, Patagonia, Argentina.
abstract: OBJECTIVE
  The timing and duration of breastfeeding and weaning in past hunter-gatherer populations are discussed based on the results of stable carbon and nitrogen isotope analyses undertaken on a Late Holocene skeletal sample from Lake Salitroso in the Patagonian steppe (Argentina). Research in Lake Salitroso is part of a regional project that studies the relationship between hunter-gatherer societies, their organizational systems and the environmental changes during the last 3,000 years in Patagonia.
  
  
  METHODS
  The sample included 52 individuals: 33 subadults and 19 adults of both sexes. They were recovered from 24 burial stone structures, locally called chenques, with dates ranging from ca. 800 BP to 350 BP. Ribs were selected for collagen extraction and measurement of (13) C/(12) C and (15) N/(14) N ratios.
  
  
  RESULTS
  A δ(13) C mean value of -18.7‰ ± 0.5‰ was obtained, with a range between -19.8‰ and -17.1‰ whereas δ(15) N recorded a mean of 11.9‰ ± 1.1‰ with a range between 10.1‰ and 14.8‰. δ(15) N data showed an age-related pattern with particularly marked difference between values for subadults under the age of 4 and older individuals. As opposed to δ(15) N, δ(13) C showed little variation with age.
  
  
  CONCLUSIONS
  An early incorporation of supplementary solid food between 0.75 and 2 years of age and a late cessation of breastfeeding at about 5-6 years of age were inferred. This suggests that among this Patagonian hunter-gatherer population weaning was a gradual and lengthy process. These results are consistent with the patterns observed in cross-cultural studies and archaeological samples of hunter-gatherer groups.
authors.affiliation: Instituto de Geocronología y Geología Isotópica, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, C1428EHA, Argentina.
authors.forename: Augusto
authors.initials: A
authors.lastname: Tessone
authors.affiliation: Instituto Nacional de Antropología y Pensamiento Latinoamericano, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, C1426BJN, Argentina.
authors.forename: Solana
authors.initials: S
authors.lastname: García Guraieb
authors.affiliation: Instituto Nacional de Antropología y Pensamiento Latinoamericano, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, C1426BJN, Argentina.
authors.forename: Rafael A
authors.initials: RA
authors.lastname: Goñi
authors.affiliation: Instituto de Geocronología y Geología Isotópica, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, C1428EHA, Argentina.
authors.forename: Héctor O
authors.initials: HO
authors.lastname: Panarello
mesh_terms: D000293:Adolescent; D000328:Adult; D000885:Anthropology, Physical; D001106:Archaeology; D001118:Argentina; D001942:Breast Feeding; D002247:Carbon Isotopes / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D003094:Collagen / Q000737:chemistry; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D014886:Weaning; D055815:Young Adult
chemical_list: D002247:Carbon Isotopes; D003094:Collagen
keywords: Patagonia; breastfeeding; collagen; hunter-gatherers; stable isotope analysis