Earlier relatives may have climbed out of family tree

It has long been believed that coming down from the trees was a crucial evolutionary shift. The behaviour of these chimpanzees suggests a more deep-seated, gradual transition." - —Kathelijne Koops The first study into rarely-documented ground nest-building by wild chimpanzees has offered new clues about the ancient transition of early hominins - our "human-like" ancestors  - from sleeping in trees to sleeping on the ground. While most apes build nests in trees, the study, published in the American Journal of Physical Anthropology , focused on a group of wild, West African chimpanzees, that often show ground-nesting behaviour. It suggests that sleeping on the ground, once thought to have been a key part of the evolutionary shift among the early ancestors of modern humans, was actually a more gradual process. An international team of primatologists from the University of Cambridge and Kyoto University, led by Kathelijne Koops, studied the chimpanzee ( Pan troglodytes verus ) population in the Nimba Mountains in Guinea, West Africa. All species of great ape build nests to sleep in each night. Construction of these shelters takes minutes as the apes bend, break and interweave branches into a circular frame, then tuck in smaller branches to form a sturdy but comfortable sleeping platform.