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PLoS One. 2014 Feb 3;9(2):e87288. doi: 10.1371/journal.pone.0087288. eCollection 2014.

Anatomical analysis of thumb opponency movement in the capuchin monkey (Sapajus sp).

Author information

1
Laboratory of Anthropology, Biochemistry, Neuroscience and Primate Behavior, Federal University of Tocantins, Palmas TO, Brazil ; Primate Center and Laboratory of Neurosciences and Behavior, Department of Physiological Sciences, Institute of Biology, University of Brasília, Brasilia DF, Brazil.
2
Primate Center and Laboratory of Neurosciences and Behavior, Department of Physiological Sciences, Institute of Biology, University of Brasília, Brasilia DF, Brazil.
3
Department of Anatomy, Howard University College of Medicine, Numa Adams Building, Washington DC, United States of America.
4
System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
5
Laboratory of Anthropology, Biochemistry, Neuroscience and Primate Behavior, Federal University of Tocantins, Palmas TO, Brazil ; System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.

Abstract

Capuchin monkeys present a wide variety of manipulatory skills and make routine use of tools both in captivity and in the wild. Efficient handling of objects in this genus has led several investigators to assume near-human thumb movements despite the lack of anatomical studies. Here we perform an anatomical analysis of muscles and bones in the capuchin hand. Trapezo-metacarpal joint surfaces observed in capuchins indicate that medial rotation of metacarpal I is either absent or very limited. Overall, bone structural arrangement and thumb position relative to the other digits and the hand's palm suggest that capuchins are unable to perform any kind of thumb opponency, but rather a 'lateral pinch' movement. Although the capuchin hand apparatus bears other features necessary for complex tool use, the lack thumb opposition movements suggests that a developed cognitive and motor nervous system may be even more important for high manipulatory skills than traditionally held.

PMID:
24498307
PMCID:
PMC3911977
DOI:
10.1371/journal.pone.0087288
[Indexed for MEDLINE]
Free PMC Article

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