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Updated: Aug 16, 2026

Behavioral Assessment of Manual Dexterity in Non-Human Primates
Published on: November 11, 2011
[Hands and feet of Simian primates: an attempt at morphological characterization]
Abstract:
The carpal height, the length of the metacarpus, the metatarsus, and of all the phalanges of 269 simians were measured, then for each specimen, converted to percentage taking the 3rd metacarpus as the reference unit. They were then compared despite differences between specimens. The average values were determined for the different species, subspecies or families. Mathematical ratios were established: height of the carpus divided by the 3rd metacarpus, carpus divided by the 1st metacarpus, 1st ray of the hand divided by the 2nd, 1st ray of the hand divided by the 1st ray of the foot. CONCERNING THE HAND: For little monkeys, the length of the carpus and the medial metacarpus were similar to those observed in humans. Colobinae exhibited a relatively short thumb column. The length of the thumb was slightly shorter for the platyrrhinii and cercopithecinae, especially macacus. Some hapalidae had a relatively longer thumb than humans. All of their medial fingers were longer than those observed in humans. The big monkeys had a smaller carpus and thumb column, sometimes much smaller than in humans, with a similar length for the metacarpi and the medial fingers, except for gibbons, whose medial fingers were longer. CONCERNING THE FOOT: The 1st ray in humans is nearly as long as the 2nd toe, the other toes being very short. The 1st ray of the hallux of all monkeys was always longer than the ray of the thumb, but shorter than the hallux of humans. The other metatarsi of little monkeys were similar to those in humans, except for the platyrrhinii which had a shorter 2nd metatarsus. The lateral toes, which were much longer than in humans, were very similar to fingers though slightly longer, except for platyrrhinii with much longer toes. The big monkeys had very short metatarsi and slightly smaller lateral toes than humans.
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