Did Our Last Ape Ancestor Climb Trees Like a Gorilla? New Study Says Maybe

What Happened A new study is stirring up the long-running debate over how our earliest ape ancestors actually got around. Researchers looking at the last common ancestor (LCA) shared by humans and chimpanzees are proposing that this creature may have moved primarily as a vertical climber — shimmying up and down tree trunks — regardless of what its feet looked like. That last part matters: for decades, scientists have leaned heavily on foot anatomy to guess how ancient primates moved, assuming grasping, ape-like feet meant knuckle-walking or swinging through branches. This research pushes back on that assumption.

Why It Matters How the LCA moved is one of the biggest open questions in human evolution. It shapes everything downstream — including how and why our ancestors eventually stood up and walked on two legs. If the LCA was a vertical climber rather than a knuckle-walker (like modern chimps) or a suspensory swinger (like orangutans), that changes the starting point for the whole story of bipedalism. Basically, scientists have been trying to reverse-engineer grandma's gait from a body that no longer exists, and every new clue reshuffles the picture.

The Bigger Picture For a long time, chimpanzee locomotion — knuckle-walking on the ground, climbing occasionally — was treated as the default model for what our shared ancestor probably did, since chimps are our closest living relatives. But that assumption has been getting chipped away at by fossil evidence (like Ardipithecus and older hominins) that doesn't neatly match chimp-style movement. Vertical climbing, think a gorilla or an orangutan hugging a tree trunk and pushing upward with powerful limbs, requires a different set of muscular and skeletal adaptations than either knuckle-walking or swinging arm-over-arm through the canopy.

The twist here is the feet detail. Feet are usually a go-to clue for reconstructing locomotion because grasping toes suggest climbing, while flatter, stiffer feet suggest ground travel. This study argues that vertical climbing could have been the dominant mode of movement even across ancestors with fairly different foot shapes, meaning researchers may need to stop treating foot morphology as the be-all-end-all indicator of how an extinct primate moved.

What This Means for the Bipedalism Story If vertical climbing was the ancestral norm, upright walking on two legs might have evolved more directly from an already partially upright climbing posture, rather than from a four-legged, ground-dwelling knuckle-walker flattening its stance over millions of years. That's a meaningfully different evolutionary path, and it's the kind of foundational shift that ripples through textbooks, museum exhibits, and the next generation of fossil analysis.

The debate is far from settled. But it's a good reminder that our understanding of "where we came from" keeps evolving right alongside the fossils and models scientists use to study it.