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Did modern human carpal morphology evolve from knuckle walking traits?
Laura E Hunter1, Matthew W Tocheri2,3,4, Caley M Orr5,6
1Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, IL, USA.
Proceedings. Biological Sciences
|May 19, 2026
Summary
Fossil hominin wrist bones show ape-like features possibly for knuckle-walking, with modern human traits evolving later. This suggests early hominins likely didn't knuckle-walk or use tools extensively.
Area of Science:
- Paleoanthropology
- Primate Anatomy
- Evolutionary Biology
Background:
- Hominin hand evolution from locomotion to manipulation is debated.
- Carpal morphology is key to understanding fossil hominin hand function.
- Quantifying carpal morphology is challenging due to irregular shapes.
Purpose of the Study:
- To comprehensively analyze and quantify carpal morphology in fossil hominins.
- To compare fossil hominin carpal morphology with extant anthropoids.
- To infer functional capabilities and evolutionary pathways of hominin hands.
Main Methods:
- Utilized spherical harmonics to analyze overall carpal morphology.
- Applied classification methods to contextualize fossil hominins within extant taxa.
- Examined carpal morphology across anthropoids, including fossil hominins.
Main Results:
- Hominins share derived carpal morphology with African apes, potentially linked to knuckle-walking.
- Modern human carpal morphology evolved gradually from these ancestral features.
- Some hominin capitates resemble those of palmigrade monkeys, indicating mosaic evolution.
- Significant variation and retention of ancestral features persist even in Homo naledi.
Conclusions:
- Hominin carpus evolved from an African ape-like wrist.
- Radial-side reorganization for manipulation occurred recently in human evolution.
- Most hominins likely did not knuckle-walk or extensively use stone tools.
- Knuckle-walking in the last common ancestor (LCA) remains the most probable hypothesis.
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