Study
Chimpanzee super strength and human skeletal muscle evolution
O'Neill, Matthew C.; Umberger, Brian R.; Holowka, Nicholas B.; Larson, Susan G.; Reiser, Peter J.
Proceedings of the National Academy of Sciences, 2017
Individual muscle fibres from chimpanzees were tested directly for force, shortening velocity and power, their fibre-type composition determined, and the results fed into a musculoskeletal model to predict whole-muscle performance relative to humans. This replaced a century of inference from whole-animal pulling feats.
- Studied in
- Pan troglodytes, Homo sapiens
- Sample size
- muscle fibre samples from chimpanzees and humans, plus simulation
Chimpanzee muscle fibres are not intrinsically stronger than human fibres. The measured difference in dynamic force and power output is roughly 1.35-fold, and it is explained almost entirely by fibre-type distribution — chimpanzees carry a higher proportion of fast-twitch fibres — rather than by any difference in the contractile machinery itself.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Ape "super strength" is a modest difference arising from fibre-type composition, and human muscle appears to have shifted towards slow, fatigue-resistant fibres during our own evolution.
How NatureHQ reads it
The reason this study is cited on a gorilla page is that no equivalent measurement exists for gorillas, and this is the closest thing there is: the same question, asked properly, in the ape it could actually be asked of. The answer is about 1.35 times, not four or eight or ten. The multipliers in circulation descend from a handful of 1920s dynamometer trials on captive apes whose motivation and technique could not be controlled, and each retelling has rounded upward. Gorillas are far heavier than people, so absolute force is genuinely much greater — but that is a size difference, and calling it a strength multiplier is a category error. Muscle is muscle.
- Chimpanzees, not gorillas; no comparable fibre-level measurement exists for gorillas.
- Fibre-level performance is combined with a model to reach whole-body predictions.
- Small samples, necessarily, given the difficulty of obtaining ape muscle tissue.
Testing ape strength one muscle fibre at a time
Are ape muscles actually stronger than human muscles, and by how much?
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.1619071114
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.