Did European colonial influence in the Pacific begin in the 1800s? There is evidence to suggest that it started much earlier. Supported by the Marie Skłodowska-Curie Actions programme, the PacificPeopleForest project is studying how European contact as early as the 16th century may have triggered major demographic shifts from inland to coastal settlements. For instance, as populations abandoned upland areas, forests reclaimed the land. This means these forests, often considered native, may be younger and more altered than assumed. The project will focus on the Mariana Islands, and its research combines archaeology, history and plant science. The findings can help address today’s climate and demographic challenges across the Pacific region.