![]() Unfortunately, these previous studies, which are based exclusively on behavior, ascribed functional capacities to the capuchin’s hand apparatus in the absence of prior anatomical analyses. Any degree of opposition would indicate an important evolutionary convergence with apes and humans, with serious implications on the selective pressures and habits (such as arboreality, terrestrialism), which are thought to have influenced the inception of tool use. Although thumb opposition may not be required for all precision grips strategies, it does grant considerable control while handling fine objects. Napier, has described the capuchin thumb as pseudo-opposable mostly due to a lack of a grip using the finger pulps however, reports of strong lateral (thenar) grips between the thumb and the index finger have led other authors to describe it as ‘lateral opposition’. This probably stems from the limited ability to rotate the thumb towards other fingers in the capuchins. Nevertheless, contact between the thumb and the index finger pulps have not been reported in this genus, as is the case for humans and a few other catarrhine genera. In such movements, the object is generally grabbed between the lateral (thenar) surfaces of the distal phalanges. Christel and Fragaszy indicated that although the capuchin monkeys use all digits together for flexion and extension, they were able to perform some form of fine grips.Ĭapuchins show a variety of grips involving the thumb and the index finger. They also reported that the capuchins, less frequently, also grab peanuts between a flexed thumb and the palm, or in their thenar and hypothenar eminences. reported that the capuchins grasp food objects in the palm by closing all digits simultaneously, with the thumb flexed parallel with the fingers. ![]() Anatomical evidence so far does not corroborate this hypothesis. Functional grips to grab objects using lateral (thenar) sides of the digits have been attributed to a relative capacity to move fingers independently. Nevertheless, more recent investigators have claimed to show evidence of such behaviors in the capuchins –. ![]() It was traditionally held that no New World primate genera are able to perform precision grips. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist. Aversi-Ferreira received a research fellowship from National Council of Technology and Development (CNPq/Brazil). Aversi-Ferreira was recipient of a doctoral fellowship from CAPES/Brazil and T.A. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.įunding: This research was supported in part by the JSPS Asian Core Program, Japan. Received: AugAccepted: DecemPublished: February 3, 2014Ĭopyright: © 2014 Aversi-Ferreira et al. PLoS ONE 9(2):Įditor: Brock Fenton, University of Western Ontario, Canada (2014) Anatomical Analysis of Thumb Opponency Movement in the Capuchin Monkey ( Sapajus sp). Citation: Aversi-Ferreira RAGMF, Maior RS, Aziz A, Ziermann JM, Nishijo H, Tomaz C, et al.
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