Early Humans May Have First Walked Upright in the Trees
Published:08 Jan.2023    Source:University College London
In the study, published today in the journal Science Advances, researchers from UCL, the University of Kent, and Duke University, USA, explored the behaviours of wild chimpanzees -- our closest living relative -- living in the Issa Valley of western Tanzania, within the region of the East African Rift Valley. Known as savanna-mosaic -- a mix of dry open land with few trees and patches of dense forest -- the chimpanzees habitat is very similar to that of our earliest human ancestors and was chosen to enable the scientists to explore whether the openness of this type of landscape could have encouraged bipedalism in hominins.

The study is the first of its kind to explore if savanna-mosaic habitats would account for increased time spent on the ground by the Issa chimpanzees, and compares their behaviour to other studies on their solely forest-dwelling cousins in other parts of Africa. Overall, the study found that the Issa chimpanzees spent as much time in the trees as other chimpanzees living in dense forests, despite their more open habitat, and were not more terrestrial (land-based) as expected. Furthermore, although the researchers expected the Issa chimpanzees to walk upright more in open savanna vegetation, where they cannot easily travel via the tree canopy, more than 85% of occurrences of bipedalism took place in the trees.