Not one great country can be named, from the polar regions in the north to New Zealand in the south, in which the aborigines do not tattoo themselves.

Darwin is making an ethnographic generalization: across widely separated regions and cultures, Indigenous peoples practice tattooing. In his hands, the observation functions as evidence that body-marking is a near-universal human custom rather than a local peculiarity, and it supports his broader interest in how aesthetic preferences, social signaling, and sexual selection might shape human behavior. The sweep “from the polar regions…to New Zealand” emphasizes geographic breadth and implies that tattooing arises repeatedly under diverse conditions—suggesting deep roots in human social life (identity, status, group belonging) rather than a single origin or diffusion from one center.