About the first human settlements in South Pacific. South Pacific includes Australia and the Pacific Islands: Melanesia, Micronesia, Polynesia. Which human populations settled them? When, why and how? Where did they come from? Did environment influence these migrations? An exhaustive discussion of these vast questions could not be undertaken rigorously within the framework of this short article. We thus propose to discuss here very precise points that could bring a new lighting on the first settlements of South Pacific. According to the oldest archaeological sites of Australia, first arrivals of Homo sapiens in the area occurred at least 40 000 years ago, and possibly as early as 50 to 60 ka BP. From a palaeoanthropological point of view, the question of the origin of these anatomically modern H. sapiens is under debate for several years: did they come from a relatively recent ‘out of Africa’ migration (Out-of-Africa hypothesis) or did they evolve locally from the last Indonesian H. erectus (multiregional hypothesis)? Partisans of these two models disagree on several fundamental points, and particularly on the interpretation of certain morphometric affinities between the most recent Indonesian H. erectus and the ‘robust’ Australian fossil H. sapiens from Kow Swamp and Cohuna. The application of 3D geometric morphometrics (Procrustes analysis) makes it possible to approach this question under a new angle. The shapes of these two sets of fossil hominids are clearly distinct, questioning seriously the assumption of a local direct evolution. For these oldest human settlements as well as for later migrations, multidisciplinary studies (archaeology, palaeoenvironment, palaeoanthropology, genetic, and linguistic) allow us to reconstruct the outlines of the first human settlements of these areas. Climate and environment interacted with these migrations of populations. The very first example is the formation of land bridges between Asian mainland and the Indonesian archipelago during Quaternary glaciations allowing the passage of humans and fauna. And periods of lower sea levels possibly also favoured dispersion from islands to islands. Winds and sea currents, directly related with climate and its variations, also intervened in the settlement of the Pacific. Natural environment, which is impoverished eastward, has been enriched by animals and plants transported by humans. In relation to their way of life as well as to available resources, peoples initially settled littoral zones (Lapita sites), then moved inland very quickly, as demonstrated by excavations carried out in the North of Grande Terre, New Caledonia. To cite this article: A.-M. Sémah, C. R. Palevol 5 (2006).