Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support
Abstract 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...
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2017-04-01
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doaj-13e11cdb9e424ffdb36c857ad35276612020-12-08T00:12:22ZengNature Publishing GroupScientific Reports2045-23222017-04-017111210.1038/s41598-017-01265-7Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip supportL. Johannsen0S. R. L. Coward1G. R. Martin2A. M. Wing3A. van Casteren4W. I. Sellers5A. R. Ennos6R. H. Crompton7S. K. S. Thorpe8Department for Sport and Health Sciences, Technische Universität MünchenSchool of Biosciences, University of BirminghamSchool of Biosciences, University of BirminghamSchool of Psychology, University of BirminghamMax Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary AnthropologyFaculty of Life Sciences, University of ManchesterSchool of Biological, Biomedical and Environmental Sciences University of HullSchool of Biomedical Sciences, University of LiverpoolSchool of Biosciences, University of BirminghamAbstract 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.https://doi.org/10.1038/s41598-017-01265-7 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
L. Johannsen S. R. L. Coward G. R. Martin A. M. Wing A. van Casteren W. I. Sellers A. R. Ennos R. H. Crompton S. K. S. Thorpe |
spellingShingle |
L. Johannsen S. R. L. Coward G. R. Martin A. M. Wing A. van Casteren W. I. Sellers A. R. Ennos R. H. Crompton S. K. S. Thorpe Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support Scientific Reports |
author_facet |
L. Johannsen S. R. L. Coward G. R. Martin A. M. Wing A. van Casteren W. I. Sellers A. R. Ennos R. H. Crompton S. K. S. Thorpe |
author_sort |
L. Johannsen |
title |
Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support |
title_short |
Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support |
title_full |
Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support |
title_fullStr |
Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support |
title_full_unstemmed |
Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support |
title_sort |
human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support |
publisher |
Nature Publishing Group |
series |
Scientific Reports |
issn |
2045-2322 |
publishDate |
2017-04-01 |
description |
Abstract 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. |
url |
https://doi.org/10.1038/s41598-017-01265-7 |
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