Département D'Anthropologie, Université de Montréal, Pavillon Lionel-Groulx, 3150 Jean-Brillant, Montréal, QC, H3T 1N8, Canada.
Department of Anthropology and Archaeology, University of Calgary, 2500 University Dr. N.W., Calgary, AB, T2N 1N4, Canada.
J Hum Evol. 2020 Jun;143:102794. doi: 10.1016/j.jhevol.2020.102794. Epub 2020 May 1.
Premasticated food transfer, when an individual partially breaks down food through chewing and feeds it to another individual, usually mouth-to-mouth, is described widely across human cultures. This behavior plays an important role in modern humans' strategy of complementary feeding, which involves supplementing maternal milk in infant diets with processed, easily digestible versions of adult foods. The extent to which other primates engage in premasticated food transfer with infants is unclear, as premasticated food transfers have been only occasionally reported in other ape species. We investigated premasticated food transfers in 62 mother-infant pairs of wild chimpanzees at Ngogo, Uganda, as well as unresisted food taking, when mothers passively allow infants to seize food. We evaluated the presence or absence and rates of premasticated food transfer and unresisted food taking relative to maternal parity and infant age and sex and assessed the food species and part used. We found that chimpanzee mothers regularly shared premasticated food with their infants aged between 6 months and 4 years, but they were more likely to share, and more frequently shared, with younger infants. The frequency with which females shared premasticated food may relate to maternal experience, as multiparous females shared premasticated food more often than did first-time mothers, which we did not find with unresisted food taking. Both easy-to-chew, commonly eaten foods and tougher, rarely eaten foods were shared. Premasticated food transfer and unresisted food taking may be infant-rearing strategies to facilitate the transition from a diet of exclusive maternal milk to solid food during early infancy. Premasticated food transfer in particular may provide energetic, immune, or growth benefits to infants through reduced chewing effort and maternal saliva. Given our findings in chimpanzees and earlier reports in other ape species, we suggest that the foundation of complementary feeding, a uniquely hominin strategy, might have been present in a common ancestor shared with the other great apes in the form of premasticated, mouth-to-mouth food transfer by mothers with their offspring.
经咀嚼后将食物传递给另一个人（通常是嘴对嘴）的预咀嚼食物转移，在人类文化中被广泛描述。这种行为在现代人类的补充喂养策略中起着重要作用，其中包括在婴儿饮食中用加工过的、易消化的成人食物来补充母乳。其他灵长类动物在多大程度上与婴儿进行预咀嚼食物转移尚不清楚，因为在其他猿类物种中，仅偶尔有报道过预咀嚼食物转移。我们在乌干达恩戈戈的 62 对野生黑猩猩母子中调查了预咀嚼食物转移，以及当母亲被动地让婴儿抓住食物时，未经抵抗的食物摄取。我们评估了预咀嚼食物转移和未经抵抗的食物摄取的存在与否及其相对于母亲的生育次数和婴儿的年龄和性别，评估了使用的食物种类和部分。我们发现，黑猩猩母亲经常与 6 个月至 4 岁的婴儿分享预咀嚼食物，但她们更有可能与年幼的婴儿分享，而且更频繁地分享。雌性分享预咀嚼食物的频率可能与母性经验有关，因为多产的雌性比初产的母亲更频繁地分享预咀嚼食物，而我们在未经抵抗的食物摄取中没有发现这种情况。既包括易于咀嚼的、常见的食物，也包括更难咀嚼的、很少吃的食物。预咀嚼食物转移和未经抵抗的食物摄取可能是婴儿喂养策略，以促进从纯母乳饮食向婴儿早期固体食物的过渡。特别是预咀嚼食物转移可能通过减少咀嚼努力和母亲唾液为婴儿提供能量、免疫或生长益处。鉴于我们在黑猩猩中的发现以及其他猿类物种中的早期报告，我们认为，补充喂养的基础，一种独特的人类策略，可能以母亲与其后代之间的预咀嚼、嘴对嘴食物转移的形式存在于与其他大猿类共享的共同祖先中。
