Certain bones in the A. afarensis foot are long and curved like those of chimpanzees11. Curved toes (phalanges) enhance a chimpanzee’s ability to grasp a tree trunk or branch while climbing. Since humans don’t regularly climb trees, humans have short, straight toes instead, to help propel themselves while walking. Although the transformation to bipedalism was underway, Lucy probably continued to climb trees to escape predators, reach for fruit, a use the tree tops as a safe place for sleeping.
