Developmental changes in feeding behaviors of infant chimpanzees at Mahale, Tanzania: Implications for nutritional independence long before cessation of nipple contactDevelopmental changes in feeding behaviors of infant chimpanzees at Mahale, Tanzania: Implications for nutritional independence long before cessation of nipple contact
Objectives: Weaning of chimpanzees is considered to occur at 4-5-years-old with completecessation of nipple contact and timing of reconception calculated by inter-birth interval minus ges-tation length. This is also the basis of “early weaning” in humans (i.e., approximately 2.5-years-old).However, recent studies of the survival of orphans and the first molar (M1) eruption in wild chim-panzees have predicted that infants move toward nutritional independence at 3-years-old.Therefore, this study aimed to investigate ontogeny of feeding behavior at around 3-years-old inwild infant chimpanzees.Materials and methods: I studied 19 infants aged 1-60 months in the M group in MahaleMountains National Park, Tanzania. The total observation time was 518 h, 25 min.Results: At around 3-years-old, infant chimpanzees spent more total feeding time, and timefeeding on leaves, and food physically difficult to process without food transfer from other individ-uals. These results suggest that infant chimpanzees significantly reduced their dependence on milkfor nutrition at around 3-years-old, that is, before cessation of nipple contact.Discussion: This study suggests that M1 eruption in wild Eastern Chimpanzees is an index of theperiod when infants move toward nutritional independence with a key dietary transition. This isthe first study to provide behavioral evidence of the large temporal gap between nutritional inde-pendence of infants and reconception of mothers in great apes, and clarify the unique feature ofhuman life history whereby mothers can reconceive before an infant reaches nutritionalindependence.
dietary transition food transfer life history variable M1 eruption weaning
This is the peer reviewed version of the following article: Matsumoto T. Developmental changesin feeding behaviors of infant chimpanzees at Mahale, Tanzania:Implications for nutritional independence long before cessationof nipple contact . Am J Phys Anthropol. Volume 163, Issue 2 (2017-06);163:356–366.https://doi.org/10.1002/ajpa.23212, which has been published in final form at https://doi.org/10.1002/ajpa.23212. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."