In this paper we review and assess the impact of colonizing peoples on their landscape by focusing on two very different colonizing processes within the western Pacific. The first is the initial human colonization of New Guinea 45,000–40,000 years ago by hunter-foraging populations; the second is the colonization of smaller offshore islands of the Bismarck Archipelago, some 3,300 years ago, by peoples argued to have practiced agriculture: two different colonizing processes by two different groups of peoples with two different social structures practicing two very different subsistence strategies. The impact of these two colonization processes on the environment is compared and contrasted, and commonalities identified for the archaeological and vegetation record.