However, the archaeological record indicates a gradual evolution of a neolithic culture that varied in pace and extent according to local resources and conditions.[68] In the course of a few centuries, the growing population led to competition for resources and an increase in warfare. The archaeological record reveals an increased frequency of fortified pā, although debate continues about the amount of conflict. Various systems arose which aimed to conserve resources; most of these, such as tapu and rāhui, used religious or supernatural threats to discourage people from taking species at particular seasons or from specified areas