Nest architecture as overlooked material culture: the case for systematic study of 1 construction behaviour across nest-building primates

Andrea L. Permana 

Frans de Waal's work highlighted an uncomfortable question: not whether animals have complex cognitive lives, but why we are so reluctant to recognise them. Nest building in great apes is perhaps the most striking example of this problem. Every great ape builds a nest, every day, for the entirety of its adult life. The behaviour has been documented ecologically for decades. Yet the internal structure of a single nest has never been systematically examined. Here I argue that this oversight has allowed us to badly underestimate both the structural sophistication and the cognitive demands of one of the most widespread forms of material culture in the primate order. Evidence from the first systematic reverse engineering of orangutan nests reveals consistent architectural patterns conserved across two species. These patterns require complex goal-directed manipulations, apparently vary culturally, and are consistent with published descriptions of chimpanzee nest frames, pointing to a shared hominid blueprint predating the divergence of great ape lineages some 14 to 18 million years ago. The same logic that justified decades of detailed study of primate tool use demands that nest construction be examined with comparable rigour across nest-building primates. Nest architecture is a new empirical domain for understanding the evolution of construction behaviour, cultural transmission, and the cognitive foundations of material culture.