Scientists studying sooty mangabey monkeys in West Africa have discovered unexpected foot flexibility that enables vertical tree climbing, suggesting our ancient ancestors might have moved more like monkeys than previously thought.
- Sooty mangabey monkeys in West Africa can climb vertical trunks using flexible foot joints.
- This challenges the idea that ape-like feet were necessary for vertical climbing in human ancestors.
- Findings offer new insight on how our last common ancestor with chimpanzees might have moved.
What happened
Anthropologists from Ohio State University studied wild sooty mangabey monkeys in Ivory Coast and recorded detailed video footage of their climbing behavior. Despite lacking highly flexible chimpanzee-like ankles, these monkeys demonstrated an ability to bend their midfoot significantly, up to 46 degrees, allowing them to climb narrow vertical tree trunks effectively. Previously, scientists believed that only ape-like ankle flexibility enabled such vertical climbing.
This new evidence suggests that the last common ancestor (LCA) of humans and chimpanzees—who diverged around 6 to 7 million years ago—might also have possessed feet capable of climbing trees efficiently, even if those feet resembled monkey-like anatomy rather than an ape’s. These findings challenge long-standing assumptions about the LCA’s locomotion and emphasize functional equivalence between different foot structures.
Why it feels good
Understanding the LCA’s movement helps illuminate the evolutionary path that led to humans’ unique bipedal gait. Demonstrating that vertical climbing did not require an ape-like foot opens up new possibilities for how early hominins moved through forest environments, blending traits we previously separated as exclusive to either apes or monkeys.
This discovery promotes a more nuanced appreciation of evolutionary diversity and adaptation, showing how different species may arrive at similar functional abilities through distinct anatomical means. It also highlights the value of modern animal behavior studies to inform paleontological interpretations, bringing fresh perspectives to a scientific puzzle millions of years old.
What to enjoy or watch next
Readers interested in the origins of human locomotion might explore further work from the Taï Forest Monkey Project that documents primate behavior in natural settings with high-resolution video technology. Observing how other monkey and ape species move can provide deeper insight into the complex evolutionary story connecting humans to their closest relatives.
For those fascinated by human ancestry and fossil interpretation, upcoming research and debates in paleoanthropology may revisit fossil foot morphology with this new context in mind. This evolving story encourages curiosity about the dynamic relationship between anatomy, environment, and behavior over millions of years.