Research Institute for Humanity and Nature, 457-4 Motoyama, Kamigamo, Kita, Kyoto, 603-8047, Japan.
J Hum Evol. 2019 Aug;133:13-22. doi: 10.1016/j.jhevol.2019.05.009. Epub 2019 Jun 14.
Modern human (Homo sapiens) children are generally considered to be dependent on older individuals for foods, even after weaning. However, recent studies of hunter-gatherer societies have reported that children can also acquire food by themselves, although the degree of self-provisioning by children differs among groups and is considered a facultative adaptation. To investigate the dependence of children on older individuals for food and the importance of self-provisioning in early hominins, I examined feeding behavior in wild, immature chimpanzees (Pan troglodytes schweinfurthii). I studied 19 mother-offspring chimpanzee pairs in the Mahale Mountains National Park, Tanzania for approximately 22 months. Feeding behavior and interactions between mothers and their offspring were recorded. The results supported these three predictions: (1) immature chimpanzees need to feed more frequently than mothers because of increased basal metabolic rate and immature stomach capacity; (2) mothers provide effective opportunities to feed on high-quality food items which are similar to those of the mothers'; and (3) when feeding independently of their mothers, immature chimpanzees consume highly accessible food including non-adult foods nearby mothers to avoid getting lost and physical burden as with self-provisioning of human children in hunter gatherer societies. During non-simultaneous feeding bouts, immature individuals frequently consumed pith and wood. They may be valuable food items for immature individuals during their growth stage because they can be consumed year round and contain relatively higher crude ash and protein amounts, which may enable immature chimpanzees to manage the confines of their immature bodies, preventing them from matching adult feeding rhythms. This opportunistic feeding strategy is similar to self-provisioning by human children in hunter-gatherer societies. These results suggested that early hominin children performed self-provisioning based on opportunistic feeding strategies, and contributed to their food consumption by snacking in accordance with their metabolic needs and physical confines.
现代人类（智人）的儿童通常被认为依赖于年龄较大的个体获取食物，即使在断奶后也是如此。然而，最近对狩猎采集社会的研究报告称，儿童也可以自己获取食物，尽管儿童的自给自足程度因群体而异，被认为是一种兼性适应。为了研究儿童对老年人的食物依赖以及自我供应在早期人类中的重要性，我研究了野生、未成年黑猩猩（Pan troglodytes schweinfurthii）的喂养行为。我在坦桑尼亚的马哈勒山国家公园研究了 19 对母婴黑猩猩，大约 22 个月。记录了喂养行为和母亲及其后代之间的相互作用。研究结果支持了以下三个预测：（1）由于基础代谢率和不成熟胃容量的增加，未成年黑猩猩需要更频繁地进食；（2）母亲提供了有效机会来喂养高质量的食物，这些食物与母亲的食物相似；（3）当独立于母亲进食时，未成年黑猩猩会食用高度可及的食物，包括附近母亲的非成人食物，以避免迷路和身体负担，就像狩猎采集社会中人类儿童的自我供应一样。在非同时喂养期间，未成年个体经常食用髓心和木材。它们可能是未成年个体在生长阶段的宝贵食物，因为它们可以全年食用，并且含有相对较高的粗灰分和蛋白质含量，这可能使未成年黑猩猩能够控制其不成熟身体的限制，防止它们与成年的进食节奏相匹配。这种机会主义的喂养策略类似于狩猎采集社会中人类儿童的自我供应。这些结果表明，早期人类的儿童基于机会主义的喂养策略进行自我供应，并根据其代谢需求和身体限制通过零食来促进其食物消耗。
