The 1800 km-long Aleutian archipelago represents a model ecosystem to track human–environmental interactions across space and through time. Defining the southern margin of Beringia across which much of the early peopling of the Americas occurred, the Aleutians present a 9000 year record of human occupation in the eastern part of the island chain, and more than 3000 years in the west. Molecular evidence demonstrates: (1) that Aleuts shared common ancestry with Chukchi and Siberian Eskimos of Chukotka; (2) the original patterns of migration into the Aleutian islands were from the Alaskan peninsula in a westward direction with no evidence for island-hopping from Kamchatka; and (3) a highly significant statistical relationship between geography and genetics, based on mtDNA sequences, was observed despite previous population disruption. Historically, the Aleutian region is a rich ecotone, with ocean fisheries, abundant populations of large marine mammals, thick kelp forests, complex near-shore ecosystems and intertidal zones, spawning streams, and a highly diverse avian fauna. Each of these environments and resources has been pivotal in shaping the adaptive strategies of human occupants of the island chain since the initial colonisation of the Aleutians from the Alaskan Peninsula. In turn, Holocene human immigration, prehistoric cultural adaptations and subsequent historic events have had reciprocal impacts on the natural systems of the Aleutians.