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. 2024 May;184(1):e24902.
doi: 10.1002/ajpa.24902. Epub 2024 Feb 24.

Cortical bone architecture of hominid intermediate phalanges reveals functional signals of locomotion and manipulation

Samar M Syeda  1 , Zewdi J Tsegai  2 , Marine Cazenave  3   4   5 , Matthew M Skinner  4 , Tracy L Kivell  4
Affiliations

Cortical bone architecture of hominid intermediate phalanges reveals functional signals of locomotion and manipulation

Samar M Syeda et al. Am J Biol Anthropol. 2024 May.

Abstract

Objectives: Reconstruction of fossil hominin manual behaviors often relies on comparative analyses of extant hominid hands to understand the relationship between hand use and skeletal morphology. In this context, the intermediate phalanges remain understudied. Thus, here we investigate cortical bone morphology of the intermediate phalanges of extant hominids and compare it to the cortical structure of the proximal phalanges, to investigate the relationship between cortical bone structure and inferred loading during manual behaviors.

Materials and methods: Using micro-CT data, we analyze cortical bone structure of the intermediate phalangeal shaft of digits 2-5 in Pongo pygmaeus (n = 6 individuals), Gorilla gorilla (n = 22), Pan spp. (n = 23), and Homo sapiens (n = 23). The R package morphomap is used to study cortical bone distribution, cortical thickness and cross-sectional properties within and across taxa.

Results: Non-human great apes generally have thick cortical bone on the palmar shaft, with Pongo only having thick cortex on the peaks of the flexor sheath ridges, while African apes have thick cortex along the entire flexor sheath ridge and proximal to the trochlea. Humans are distinct in having thicker dorsal shaft cortex as well as thick cortex at the disto-palmar region of the shaft.

Discussion: Variation in cortical bone distribution and properties of the intermediate phalanges is consistent with differences in locomotor and manipulative behaviors in extant great apes. Comparisons between the intermediate and proximal phalanges reveals similar patterns of cortical bone distribution within each taxon but with potentially greater load experienced by the proximal phalanges, even in knuckle-walking African apes. This study provides a comparative context for the reconstruction of habitual hand use in fossil hominins and hominids.

Keywords: cortical bone; functional morphology; hominin manual behaviors; internal bone structure; phalangeal morphology.

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References

REFERENCES

    1. Alba, D. M., Moyà‐Solà, S., & Köhler, M. (2003). Morphological affinities of the Australopithecus afarensis hand on the basis of manual proportions and relative thumb length. Journal of Human Evolution, 44(2), 225–254. https://doi.org/10.1016/S0047-2484(02)00207-5
    1. Almecija, S., Alba, D. M., & Moyà‐Solà, S. (2009). Pierolapithecus and the functional morphology of Miocene ape hand phalanges: Paleobiological and evolutionary implications. Journal of Human Evolution, 57(3), 284–297. https://doi.org/10.1016/j.jhevol.2009.02.008
    1. Almécija, S., Alba, D. M., & Moyà‐Solà, S. (2012). The thumb of Miocene apes: New insights from Castell de Barberà (Catalonia, Spain). American Journal of Physical Anthropology, 148(3), 436–450. https://doi.org/10.1002/ajpa.22071
    1. Almécija, S., Moyà‐Solà, S., & Alba, D. M. (2010). Early origin for human‐like precision grasping: A comparative study of pollical distal phalanges in fossil hominins. PLoS One, 5(7), e11727. https://doi.org/10.1371/journal.pone.0011727
    1. Ayhan, Ç., & Ayhan, E. (2020). Kinesiology of the wrist and the hand. In S. Angin & I. Simsek (Eds.), Comparative kinesiology of the human body (pp. 211–282). Academic Press.

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