Relative to other species, humans are characterised by considerable biological diversity despite genetic homogeneity. This diversity is reflected in skeletal variation, but we lack sufficient understanding of the underlying mechanisms to adequately interpret the archaeological record. The proposed research will address problems in our current understanding of the origins of human variation in the past by: 1) documenting and interpreting the pattern of global hunter-gatherer variation relative to genetic phylogenies and climatic variation; 2) testing the relationship between environmental and skeletal variation among genetically related hunter-gatherers from different environments; 3) examining the adaptability of living humans to different environments, through the study of energetic expenditure and life history trade-offs associated with locomotion; and 4) investigating the relationship between muscle and skeletal variation associated with locomotion in diverse environments. This will be achieved by linking: a) detailed study of the global pattern of hunter-gatherer variation in the Late Pleistocene and Holocene with; b) ground-breaking experimental research which tests the relationship between energetic stress, muscle function, and bone variation in living humans. The first component tests the correspondence between skeletal variation and both genetic and climatic history, to infer mechanisms driving variation. The second component integrates this skeletal variation with experimental studies of living humans to, for the first time, directly test adaptive implications of skeletal variation observed in the past. ADaPt will provide the first links between prehistoric hunter-gatherer variation and the evolutionary parameters of life history and energetics that may have shaped our success as a species. It will lead to breakthroughs necessary to interpret variation in the archaeological record, relative to human dispersals and adaptation in the past.