Bădescu Iulia, Katzenberg M Anne, Watts David P, Sellen Daniel W
Department of Anthropology, University of Toronto, Toronto, Ontario, Canada, M5S 2S2.
Department of Anthropology and Archaeology, University of Calgary, Calgary, Alberta, Canada, T2N 1N4.
Am J Phys Anthropol. 2017 Feb;162(2):285-299. doi: 10.1002/ajpa.23116. Epub 2016 Oct 21.
Determining nutritional development in wild primates is difficult through observations because confirming dietary intake is challenging. Physiological measures are needed to determine the relative contributions of maternal milk and other foods at different ages, and time of weaning. We used fecal stable carbon and nitrogen isotopes (δ C, δ N) and fecal nitrogen concentrations (%N) from wild chimpanzees at Ngogo, Uganda, to derive physiological dietary indicators during the transition from total reliance on maternal milk to adult foods after weaning.
We analyzed 560 fecal samples collected non-invasively from 48 infants, their mothers, and 6 juvenile siblings. Most infant and juvenile samples (90%) were matched to samples collected from mothers on the same day. Isotopic assessments were compared with observations of nursing and feeding.
Infants ≤1 year old showed average δ N, δ C and %N ratios that were 2.0‰, 0.8‰ and 1.3% greater than their mothers, respectively, interpreted as trophic level effects. Although data collected on newborns were few, results suggest that solid foods were consumed within 2-5 months after birth. Trophic level differences decreased steadily after 1 year, which indicates a decreasing relative contribution of milk to the diet. Isotopic results indicated infants were weaned by 4.5 years old-more than a year earlier than observations of nipple contacts ceased, which revealed the occurrence of "comfort nursing." Juvenile isotopic signatures indicate no nursing overlap between siblings.
Our results resemble the stable isotope differences of human babies. This study contributes to a model of chimpanzee nutritional development required to understand early life history patterns in hominins.
通过观察来确定野生灵长类动物的营养发育情况很困难，因为确认饮食摄入量具有挑战性。需要生理指标来确定不同年龄段母乳和其他食物的相对贡献以及断奶时间。我们利用乌干达恩戈戈野生黑猩猩的粪便稳定碳氮同位素（δC、δN）和粪便氮浓度（%N），得出断奶后从完全依赖母乳过渡到食用成年食物期间的生理饮食指标。
我们分析了从48只婴儿、其母亲及6只幼年兄弟姐妹身上无创采集的560份粪便样本。大多数婴儿和幼年样本（90%）与同一天从母亲身上采集的样本相匹配。将同位素评估结果与哺乳和进食观察结果进行比较。
1岁及以下婴儿的平均δN、δC和%N比值分别比其母亲高2.0‰、0.8‰和1.3%，这被解释为营养级效应。尽管关于新生儿的数据较少，但结果表明出生后2 - 5个月内开始食用固体食物。1岁以后营养级差异稳步下降，这表明母乳在饮食中的相对贡献在减少。同位素结果表明婴儿在4.5岁时断奶，比乳头接触停止的观察结果早一年多，这揭示了“安慰性哺乳”的存在。幼年同位素特征表明兄弟姐妹之间不存在哺乳重叠。
我们的结果与人类婴儿的稳定同位素差异相似。本研究有助于建立一个黑猩猩营养发育模型，以了解人类早期生活史模式。
