Ogura Yukiko, Masamoto Taku, Kameda Tatsuya
Department of Social Psychology, The University of Tokyo, Japan.
Brain Science Institute, Tamagawa University, Tokyo, Japan.
R Soc Open Sci. 2020 Apr 1;7(4):200044. doi: 10.1098/rsos.200044. eCollection 2020 Apr.
Competition for food resources is widespread in nature. The foraging behaviour of social animals should thus be adapted to potential food competition. We conjectured that in the presence of co-foragers, animals would shift their tactics to forage more frequently for smaller food. Because smaller foods are more abundant in nature and allow faster consumption, such tactics should allow animals to consume food more securely against scrounging. We experimentally tested whether such a shift would be triggered automatically in human eating behaviour, even when there was no rivalry about food consumption. To prevent subjects from having rivalry, they were instructed to engage in a 'taste test' in a laboratory, alone or in pairs. Even though the other subject was merely present and there was no real competition for food, subjects in pairs immediately exhibited a systematic behavioural shift to reaching for smaller food amounts more frequently, which was clearly distinct from their reaching patterns both when eating alone and when simply weighing the same food without eating any. These patterns suggest that behavioural shifts in the presence of others may be built-in tactics in humans (and possibly in other gregarious animals as well) to adapt to potential food competition in social foraging.
对食物资源的竞争在自然界中普遍存在。因此，群居动物的觅食行为应适应潜在的食物竞争。我们推测，在有共同觅食者的情况下，动物会改变策略，更频繁地去寻找较小的食物。因为较小的食物在自然界中更为丰富，且能更快地被消耗，这样的策略应能让动物在防止被抢夺的情况下更安全地获取食物。我们通过实验测试了在人类进食行为中，即使不存在食物消费方面的竞争，这种转变是否会自动触发。为了防止受试者产生竞争，他们被要求在实验室单独或成对进行“味觉测试”。尽管另一名受试者只是在场，且不存在对食物的实际竞争，但成对的受试者立即表现出一种系统性的行为转变，即更频繁地去拿取较少的食物量，这与他们单独进食时以及只是单纯称量相同食物而不吃时的拿取模式明显不同。这些模式表明，在他人在场时的行为转变可能是人类（可能其他群居动物也是如此）为适应社会觅食中潜在的食物竞争而内置的策略。
