Département d'anthropologie, Université de Montréal, Montréal, QC, Canada.
Department of Anthropology, Yale University, New Haven, CT, United States of America.
PLoS One. 2022 Aug 4;17(8):e0272139. doi: 10.1371/journal.pone.0272139. eCollection 2022.
The interaction between infant feeding and maternal lactational physiology influences female inter-birth intervals and mediates maternal reproductive trade-offs. We investigated variation in feeding development in 72 immature wild chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda, and made inferences about maternal lactation over the course of infancy. We compared the percentage (%) of time that mothers nursed infants as a function of infant age and assessed how hourly rates and bout durations of nursing and foraging varied in association with differences in offspring age, sex, and maternal parity. Nursing % times, rates and durations were highest for infants ≤ 6 months old but did not change significantly from 6 months to 5 years old. Nursing continued at a decreasing rate for some 5- to 7-year-olds. Infants ≤ 6 months old foraged little. Foraging rates did not change after 1 year old, but foraging durations and the % time devoted to foraging increased with age. Independent foraging probably became a dietary requirement for infants at 1 year old, when their energy needs may have surpassed the available milk energy. Infants spent as much time foraging by the time they were 4 to 5 years old as adults did. No sex effect on infant nursing or foraging was apparent, but infants of primiparous females had higher foraging rates and spent more time foraging than the infants of multiparous females did. Although no data on milk composition were collected, these findings are consistent with a working hypothesis that like other hominoids, chimpanzee mothers maintained a fixed level of lactation effort over several years as infants increasingly supplemented their growing energy, micronutrient and hydration needs via independent foraging. Plateauing lactation may be a more widespread adaptation that allows hominoid infants time to attain the physiology and skills necessary for independent feeding, while also providing them with a steady dietary base on which they could rely consistently through infancy, and enabling mothers to maintain a fixed, predictable level of lactation effort.
婴儿喂养与母体哺乳期生理之间的相互作用影响女性的生育间隔，并介导了母体的生殖权衡。我们调查了乌干达基巴莱国家公园恩戈戈地区 72 只未成年野生黑猩猩（Pan troglodytes schweinfurthii）的喂养发育变化，并对婴儿期母体哺乳情况进行了推断。我们比较了母亲在婴儿年龄范围内哺乳的时间百分比（%），并评估了哺乳和觅食的每小时频率和持续时间如何与后代年龄、性别和母亲产次的差异相关变化。≤6 月龄婴儿的哺乳%时间、频率和持续时间最高，但从 6 个月到 5 岁时并没有显著变化。一些 5 至 7 岁的婴儿仍在以递减的速度哺乳。≤6 月龄的婴儿觅食很少。1 岁后觅食频率没有变化，但觅食持续时间和用于觅食的时间百分比随着年龄的增长而增加。1 岁时，独立觅食可能成为婴儿的饮食需求，因为此时他们的能量需求可能已经超过了可获得的牛奶能量。到 4 至 5 岁时，婴儿用于觅食的时间与成年人相同。婴儿的哺乳或觅食没有明显的性别影响，但初产雌性的婴儿觅食频率更高，用于觅食的时间也比多产雌性的婴儿多。尽管没有收集关于牛奶成分的数据，但这些发现与一个工作假设一致，即与其他类人猿一样，黑猩猩母亲在数年内保持固定的泌乳努力水平，而婴儿则通过独立觅食来逐渐补充其不断增长的能量、微量营养素和水分需求。稳定的泌乳可能是一种更广泛的适应，它使类人猿婴儿有时间获得独立喂养所需的生理和技能，同时为他们提供稳定的饮食基础，使他们能够在婴儿期持续依赖，并使母亲能够保持固定、可预测的泌乳努力水平。
