Hand and foot pressures in the aye-aye (Daubentonia madagascariensis) reveal novel biomechanical trade-offs required for walking on gracile digits.
Abstract
Arboreal animals with prehensile hands must balance the complex demands of bone strength,
grasping and manipulation. An informative example of this problem is that of the aye-aye
(Daubentonia madagascariensis), a rare lemuriform primate that is unusual in having
exceptionally long, gracile fingers specialized for foraging. In addition, they are
among the largest primates to engage in head-first descent on arboreal supports, a
posture that should increase loads on their gracile digits. We test the hypothesis
that aye-ayes will reduce pressure on their digits during locomotion by curling their
fingers off the substrate. This hypothesis was tested using simultaneous videographic
and pressure analysis of the hand, foot and digits for five adult aye-ayes during
horizontal locomotion and during ascent and descent on a 30 degrees instrumented runway.
Aye-ayes consistently curled their fingers during locomotion on all slopes. When the
digits were in contact with the substrate, pressures were negligible and significantly
less than those experienced by the palm or pedal digits. In addition, aye-ayes lifted
their hands vertically off the substrate instead of 'toeing-off' and descended head-first
at significantly slower speeds than on other slopes. Pressure on the hand increased
during head-first descent relative to horizontal locomotion but not as much as the
pressure increased on the foot during ascent. This distribution of pressure suggests
that aye-ayes shift their weight posteriorly during head-first descent to reduce loads
on their gracile fingers. This research demonstrates several novel biomechanical trade-offs
to deal with complex functional demands on the mammalian skeleton.
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https://hdl.handle.net/10161/4193Published Version (Please cite this version)
10.1242/jeb.040014Publication Info
Kivell, Tracy L; Schmitt, Daniel; & Wunderlich, Roshna E (2010). Hand and foot pressures in the aye-aye (Daubentonia madagascariensis) reveal novel
biomechanical trade-offs required for walking on gracile digits. J Exp Biol, 213(Pt 9). pp. 1549-1557. 10.1242/jeb.040014. Retrieved from https://hdl.handle.net/10161/4193.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Daniel Oliver Schmitt
Professor in the Department of Evolutionary Anthropology
My primary interest is in the evolution of primate locomotion. I am studying the
mechanics of movement in primates and other vertebrates in the laboratory to understand
the relationship between movement and postcranial morphology, and the unique nature
of primates among mammals. Current projects include the origins of primate locomotion
and the evolution of vertebrate bipedalism.

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