Sooty Mangabey Study Finds 46-Degree Foot Bend, Challenging Early Human Tree-Climbing Theory
Updated
Updated · studyfinds.com · Aug 18
Sooty Mangabey Study Finds 46-Degree Foot Bend, Challenging Early Human Tree-Climbing Theory
3 articles · Updated · studyfinds.com · Aug 18
Summary
Wild Sooty mangabeys in Côte d’Ivoire bent their midfoot about 46 degrees while climbing vertical trunks, essentially matching the roughly 45.5-degree ankle bend seen in chimpanzees.
That result undercuts a long-held assumption that a monkey-like foot would make vertical climbing unsafe or unlikely for early human ancestors, because monkeys and apes reached the same functional solution through different joints.
Researchers filmed 21 climbing bouts at Taï National Park and found mangabeys, once body size was accounted for, kept their bodies about as close to the trunk as chimpanzees do—a key factor in climbing stability.
The findings also fit fossil evidence from Australopithecus and other early hominins whose foot bones suggest a more flexible midfoot than modern humans, supporting the idea they could still climb effectively.
The authors say the study does not settle whether the last common ancestor had an ape-like or monkey-like foot, and note limits including one monkey species and small comparison samples.