The aim of this study is to focus on Pukapuka atoll, a remote island in the northern Cook Islands, to take a diachronic perspective and to use interdisciplinary methods to empirically illustrate how people living on a very remote atoll have responded to their fragility and vulnerability. Pukapuka atoll consists of three islets, with the northern Wale as the main islet, Motu Kō to the southeast and Motu Kotawa to the southwest. With a population of approximately 450 (as of 2019), the main island, Wale, is home to three villages, each of which has resource reserve (motu) in the northern region of Wale, Motu Uta, Motu Kō and Motu Kotawa, respectively. The period of lifting and closure of the resource reserves and the methods of utilisation and management of the resource reserves are determined each year in consultation with the members of the Island Council, who are elected from each village, and the Traditional Authorities Council (Kau Wowolo). As exemplified by the practice of the resource reserves, we are of the view that the inhabitants of extremely remote atolls, which are harsh for human habitation, are trying to stabilize their living world by carefully and meticulously securing their survival environment. We would like to characterize this process as a set of concepts of environmental functional differentiation and environmental boundary.

　More specifically, environmental functional differentiation refers to the process of positioning and cultivating a certain space constituting the environment as a place for acquiring specific living resources, while environmental boundary refers to the limits to the acquisition of living resources in the environment concerned. The inhabitants of Pukapuka utilise and manage the individual islets that make up the atoll by identifying their location and characteristics and recharging them as sites for the acquisition of specific living resources, resulting in each islet having its own separate function that supports the whole living world. In addition, after the colonisation of New Zealand in the early 20th century, the constant migration of the population out of the atolls (circulation) led to the positioning of Rarotonga in the Cook Islands, New Zealand and Australia as places where the inhabitants of Pukapuka could acquire living resources. The residents of Pukapuka Atoll have come to regard it as a place for acquiring livelihood resources. In other words, the inhabitants have increased their chances of survival by continually raising the environmental limits through environmental functional differentiation and the expansion of their target space. From a different perspective, the adoption of the concepts of environmental functional differentiation and environmental boundary is nothing other than an attempt to elucidate the permanent dynamics of this atoll society.

　With this in mind, in order to clarify the reality of the construction of the living world by the inhabitants of Pukapuka, we employ multiple research methods dealing with different time spans - (1) social anthropology, (2) historical anthropology and (3) archaeology and geography - to conduct empirical research with collaboration in the field at its core.