| Autor: |
Johannsen L; Department for Sport and Health Sciences, Technische Universität München, Munich, Germany.; School of Health Sciences, University of East Anglia, Norwich, UK., Coward SRL; School of Biosciences, University of Birmingham, Birmingham, UK., Martin GR; School of Biosciences, University of Birmingham, Birmingham, UK., Wing AM; School of Psychology, University of Birmingham, Birmingham, UK., Casteren AV; Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany., Sellers WI; Faculty of Life Sciences, University of Manchester, Manchester, UK., Ennos AR; School of Biological, Biomedical and Environmental Sciences University of Hull, Hull, UK., Crompton RH; School of Biomedical Sciences, University of Liverpool, Liverpool, UK., Thorpe SKS; School of Biosciences, University of Birmingham, Birmingham, UK. S.K.Thorpe@bham.ac.uk. |
| Abstrakt: |
Whether tree canopy habitats played a sustained role in the ecology of ancestral bipedal hominins is unresolved. Some argue that arboreal bipedalism was prohibitively risky for hominins whose increasingly modern anatomy prevented them from gripping branches with their feet. Balancing on two legs is indeed challenging for humans under optimal conditions let alone in forest canopy, which is physically and visually highly dynamic. Here we quantify the impact of forest canopy characteristics on postural stability in humans. Viewing a movie of swaying branches while standing on a branch-like bouncy springboard destabilised the participants as much as wearing a blindfold. However "light touch", a sensorimotor strategy based on light fingertip support, significantly enhanced their balance and lowered their thigh muscle activity by up to 30%. This demonstrates how a light touch strategy could have been central to our ancestor's ability to avoid falls and reduce the mechanical and metabolic cost of arboreal feeding and movement. Our results may also indicate that some adaptations in the hand that facilitated continued access to forest canopy may have complemented, rather than opposed, adaptations that facilitated precise manipulation and tool use. |
