The Study
The uniquely human capacity to throw evolved from a non-throwing primate: an evolutionary dissociation between action and perception
This study watched monkeys react to people pretending to throw things. It found that monkeys get scared when someone throws like they mean it—but not when someone just waves their arm. That means monkeys can tell the difference between a real throw and a fake one, but it doesn't prove they understand why or how throwing works.
Analysis score
Maximum 58 for a case-control study.
Where the score came from
Monkeys don’t throw, but they know when a human is about to throw something dangerous—like a rock—and they run away. They don’t care if it’s overhand or underhand, but they do care if the person is looking at them, if there’s a rock, or if it’s thrown slowly.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 512 / 100
Quality score
Researchers compare people who have a condition (cases) with similar people who do not (controls), looking back in time for differences in exposure. Useful but more prone to bias.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes—this suggests humans didn’t need to evolve new brain parts to understand throwing; our ancestors may have used existing skills to recognize threats.
- 285% ran away from fast throws with rocks; only 15% ran when the hand was empty; 20% ran when the thrower looked away.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Biology Letters
Year
2007
Authors
Justin N. Wood, David D. Glynn, M. Hauser
Related Content
Claims (6)
Rhesus monkeys that cannot throw respond with avoidance when they see humans throw objects overhead with speed and rotation, showing they recognize the threat of throwing even though they have never thrown themselves.
Rhesus monkeys are more likely to avoid fast overhand throws with rocks than slow or directionally incorrect throws without objects, based on how the motion moves through space.
Rhesus monkeys do not react fearfully to human throwing motions unless the object thrown has the potential to cause harm, showing their response depends on the object's properties, not just the motion.
The structure of the human arm and shoulder allows for fast and precise throwing of objects, and this ability evolved as part of hunting strategies.
Rhesus monkeys are less likely to avoid being thrown at when the person throwing looks away from them, showing their behavior changes based on where the thrower is looking.
Rhesus monkeys react the same way to two different types of throws, even if they have never seen one of them before, because their brains recognize the motion patterns, not because they learned what each throw means.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.