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The grazing gait, and implications of toppling table geometry for primate footfall sequences

Usherwood, J R; Smith, B J H


J R Usherwood

B J H Smith


Many medium and large herbivores locomote forwards very slowly and intermittently when grazing. While the footfall order during grazing is the same as for walking, the relative fore–hind timing—phasing—is quite different. Extended periods of static stability are clearly required during grazing; however, stability requirements are insufficient to account for the timing. Aspects of relatively rapid rolling and pitching—toppling due to the resistance of the back to bending and twisting—can be included in a simplifying geometric model to explain the observation that, in grazing livestock, a step forward with a forefoot is consistently and immediately followed by a step forward from the hind; but not vice versa. The same principles and geometry, but applied to the footfall pattern of walking primates, show that toppling would occur at a different point in the gait cycle. This provides a potential account for the distinctive diagonal-sequence footfall pattern of primates, as it prevents the instant of toppling from being at forefoot placement. Careful and controlled hand positioning would thus be facilitated, presumably beneficial to walking on top of branches, despite a slight energetic cost compared with the usual lateral sequence pattern of horses.


Usherwood, J. R., & Smith, B. J. H. (2018). The grazing gait, and implications of toppling table geometry for primate footfall sequences. Biology Letters, 14(5),

Journal Article Type Article
Acceptance Date Apr 17, 2018
Publication Date May 16, 2018
Deposit Date Jun 15, 2018
Publicly Available Date Jun 18, 2018
Journal Biology Letters
Print ISSN 1744-9561
Publisher The Royal Society
Peer Reviewed Peer Reviewed
Volume 14
Issue 5
Public URL


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