Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support

Johannsen, L. ORCID:, Coward, S. R. L., Martin, G. R., Wing, A. M., van Casteren, A., Sellers, W. I., Ennos, A. R., Crompton, R. H. and Thorpe, S. K. S. (2017) Human bipedal instability in tree canopy environments is reduced by “light touch” fingertip support. Scientific Reports, 7. ISSN 2045-2322

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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 feedback 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.

Item Type: Article
Faculty \ School: Faculty of Medicine and Health Sciences > School of Health Sciences
Depositing User: Pure Connector
Date Deposited: 06 Apr 2017 06:59
Last Modified: 31 Jan 2024 02:15
DOI: 10.1038/s41598-017-01265-7

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