Did high levels of morphological flexibility facilitate colonisation of novel habitats during human evolution?
Homo sapiens has a global distribution, a remarkable achievement for a tropical ape. Adaptations enabling this colonisation are intriguing given suggestions that humans exhibits high levels of physiological and behavioural malleability associated with a ‘colonising niche’. Differences in body size/shape between members of the same species from different climates are well-known adaptations in mammals; could relatively flexible size/shape have been important to human species adapting to novel habitats? If so, at what point did this flexibility arise? To address these questions, a base-line for adaptation to climate must be established by comparison with suitable outgroups. Japanese macaques (Macaca fuscata) are the most northerly living non-human primates. They have great latitudinal spread and overlap with the historical distribution of prehistoric Jomon foragers, allowing matched latitude comparisons within monkeys and humans and making them an ideal outgroup for this study. We compare skeletons of M. fuscata from four different latitudes, including the most northerly and most southerly extremes of the species’ distribution. Initial results show inter-group differences in M. fuscata postcranial and cranial size and shape. Size varies more than shape, showing a strong, positive relationship with latitude. However, the very small size of the southern-most (island) sample may be affected by resource availability. Allometry-free shape shows geographic patterning and perhaps echoes some trends seen in human groups at high latitudes. These insights begin to provide a comparison for human adaptation to climatic diversity and the role of colonisation in shaping the evolution and dispersal of human species.
Buck, L. T.1, 2, De Groote, I.3, Hamada, Y.4, Stock, J. T.1
1 Department of Archaeology, University of Cambridge
2 Department of Earth Sciences, Natural History Museum
3 School of Natural Sciences and Psychology, Liverpool John Moores University
4 Section of Evolutionary Morphology, Primate Research Institute, Kyoto University
Funding: This work was supported by the European Research Council (ADaPt Project: FP7-IDEAS-ERC 617627).