Study
Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor
Kivell, Tracy L.; Schmitt, Daniel
Proceedings of the National Academy of Sciences, 2009
Wrist bone features associated with knuckle-walking were scored across large skeletal samples of gorillas, chimpanzees, orangutans and humans, and the distribution of those features compared against what a single shared origin of knuckle-walking would predict.
- Studied in
- Gorilla, Pan troglodytes, Homo sapiens, Pongo
- Sample size
- wrist skeletal features scored across ape and human samples
Gorillas and chimpanzees knuckle-walk using different skeletal arrangements. Gorilla wrists show features consistent with a columnar, extended posture; chimpanzee wrists show a distinct set associated with a flexed posture. Features are distributed as expected if knuckle-walking arose separately in the two lineages, and the anatomy said to be a knuckle-walking remnant in early hominins is also found in non-knuckle-walking primates.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Knuckle-walking evolved at least twice in African apes, and the human lineage did not pass through a knuckle-walking stage.
How NatureHQ reads it
Two popular ideas fall here at once. The first is the picture of human ancestry as a march from knuckle-walking ape to upright human; the second, related, is that gorillas represent an earlier version of us. Neither survives. Gorillas are a sister lineage that has been evolving for exactly as long as we have, and their most distinctive locomotor behaviour appears to be their own invention rather than an inherited stage we grew out of. The conclusion remains argued over — knuckle-walking anatomy is subtle and the samples are noisy — but the framing correction stands regardless of how that argument settles.
- Wrist morphology is subtle and the interpretation of individual features is contested.
- Fossil evidence bearing on early hominin wrists is fragmentary.
- A single shared origin followed by divergence has been defended by other workers.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Proceedings of the National Academy of SciencesPublished in PNAS.
doi.org/10.1073/pnas.0901280106
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.