Deep ancestry of collapsing networks of nomadic hunter-gatherers in Borneo

Abstract

Theories of early cooperation in human society often draw from a small sample of ethnographic studies of surviving populations of hunter–gatherers, most of which are now sedentary. Borneo hunter–gatherers (Punan, Penan) have seldom figured in comparative research because of a decades-old controversy about whether they are the descendants of farmers who adopted a hunting and gathering way of life. In 2018 we began an ethnographic study of a group of still-nomadic hunter–gatherers who call themselves Punan Batu (Cave Punan). Our genetic analysis clearly indicates that they are very unlikely to be the descendants of neighbouring agriculturalists. They also preserve a song language that is unrelated to other languages of Borneo. Dispersed travelling groups of Punan Batu with fluid membership use message sticks to stay in contact, co-operate and share resources as they journey between rock shelters and forest camps. Message sticks were once widespread among nomadic Punan in Borneo, but have largely disappeared in sedentary Punan villages. Thus the small community of Punan Batu offers a rare glimpse of a hunting and gathering way of life that was once widespread in the forests of Borneo, where prosocial behaviour extended beyond the face-to-face community, facilitating successful collective adaptation to the diverse resources of Borneo’s forests. Keywords: Hunter–gatherers; prosocial behaviour; Borneo; Austronesia; song language Social media summary: Ancient networks of communication among mobile groups of hunter– gatherers in the forests of Borneo are collapsing. The Punan were the traditional hunter–gatherers of Borneo, but long-term resettlement programmes, deforestation and changing economic conditions have greatly reduced full-time hunting and gathering, making most communities largely sedentary (Guerreiro, 2004; Kaskija, 2002, 2007; Sercombe & Sellato, 2007; Hose & McDougall, 1912). A comprehensive census of the Punan of East Kalimantan in 2003–2004 by researchers from the Center for International Forestry Research counted 8,956 persons. The authors estimated that their census included more than 90% of the total Punan population of East Kalimantan. However, they also noted that ‘the possibility cannot be excluded that because of isolation, some Punan Basap/Batu might still exist in the Berau region’ (Sitorus et al., 2004). Our knowledge of the © The Author(s), 2022. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited. 2 J. Stephen Lansing et al. existence of an isolated community who call themselves Punan Batu (Cave Punan) came about unexpectedly in May 2018 during a medical survey of resettled Punan communities in Northeast Borneo (Figure 1a). A Punan leader from a resettlement community told us that he had recently encountered a community of Punan who live as nomadic hunter–gatherers, and offered to bring us to meet them. In July 2018 he guided us to a rock shelter where a small number of Punan Batu were encamped, and we accepted their invitation to camp nearby. Many Cave Punan spoke Malay as well as their own languages, and from them we learned that they number about 30 families, a few largely sedentary but most living as mobile foragers. In a few days, other Punan Batu joined us. With them we visited other camps and rock shelters, and expanding oil palm plantations that border their forest. Many Punan live in remote upland regions of Borneo, but the dense coastal forests of the Cave Punan are located near the town of Tanjung Selor, within the traditional territory of the former Sultanate of Bulungan. In subsequent visits we learned that a descendant of the Sultan (the Datuk) maintains an occasional trading post on the Sajau river where he trades goods for forest products. The Cave Punan we spoke with told us that most of them very seldom leave the forest, and that the availability of forest resources for trade has sharply declined. Some wear clothes fashioned from tree bark, especially for hunting, but most now wear used clothing obtained from the Datuk. These initial observations prompted several questions: do all people who come to trade with the Datuk regard themselves as Cave Punan? Are they mobile foragers? What is their relationship to each other, to the Datuk and to neighbouring Punan and tribal farming communities, both now and in the past? To answer these questions we made repeated visits to Cave Punan forest camps and rock shelters, and gathered additional data on their mobility using GPS and accelerometers. To investigate their ancestry and relationship to one another and neighbouring groups, we combined multiple independent lines of evidence from ethnology, population genetics and linguistic analysis. This approach has recently provided new insights into the origins and ancestry of other societies in the region, revealing for example that the Sama sea nomads of the Sulu archipelago share genetic ancestry with other Philippine groups who do not self-identify as Sama or speak a Sama-related language (Larena et al., 2021). Here they enable us to provide the first comprehensive cultural–genetic– linguistic study of the only known group of Punan hunter–gatherers who remain continuously mobile.