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The anatomy of the radius of curvature of the metacarpal and proximal phalangeal bones: its evolutionary connection to our nonhuman primate ancestry
Author(s) -
Pensak Michael,
Mowbray Ken,
Farber Scott,
Happes Michael,
Caceres Noel,
Marquez Samuel
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a444-b
Subject(s) - phalanx , curvature , metacarpal bones , anatomy , radius of curvature , radius , biology , geometry , mathematics , mean curvature , computer science , computer security , mean curvature flow
Morphological features of metacarpals and proximal phalanges in African apes and modern humans suggest that the evolutionary trajectory of the modern human hand may have been derived from a variety of specialized suspensory activities. This study examines the radius of curvature of the metacarpal and proximal phalanx bones in African apes (N=15) and African‐American (N=12) and European‐American (N=23) human specimens. Individual bones with a measured scale were placed on a flat surface, digitally photographed with a Minolta D100 camera, and analyzed with ImageJ NIH software to obtain chord measures needed to calculate the radius of curvature for each bone. Results consistently showed that the third metacarpal and third proximal phalanx had the largest radii of curvature while the first metacarpal and first proximal phalanx had the smallest radii of curvature. Statistically significant differences were found between African‐American and European‐American samples in all but two of the ten bones examined (first metacarpal and first proximal). The African‐American samples had larger radii of curvature in all the bones for which statistically significant data was achieved. Comparison of radii of curvature in non‐human primates and members of Hominidae should yield valuable evolutionary inferences shedding light on how changes in the curvatures of these bones preceded our committed bipedal lifestyle.