期刊名称：Evolutionary Psychology: an international journal of evolutionary approaches to psychology and behavior
印刷版ISSN：1474-7049
出版年度：2015
卷号：13
DOI：10.1177/147470491501300210
语种：English
出版社：Ian Pitchford, Ed.& Pub
摘要：Humans have engaged in unique cooperative breeding insofar as multiple in-group members help mothers. Two psychological-proximate factors maintain such a breeding system—various individuals' interest in infants and mothers' positive reactions toward individuals approaching their infants—which we investigated in the present study. In Study 1, we conducted field observations to examine the first factor: what types of passersby in Japan reacted to the mother and infant. This replicated studies conducted in Western countries more than 30 years ago, allowing for the examination of the influence of culture and time. The results confirmed the differences among age groups in frequency of looking at mother and infant, and predicted its universality, especially the rise in older adults. The sex difference was not significant. In Study 2, we gathered data via questionnaires and interviews using hypothetical scenarios to investigate the second factor: how mothers felt when their infants were approached by strangers. The results revealed that mothers received strangers' approaches positively. The present study showed that humans engaged in unique cooperative breeding in the Environment of Evolutionary Adaptedness (EEA), where mothers in modern society see strangers as potential helpers as part of the EEA.
