Final answer:
Humans have a bent hip and an angling of the femur known as the valgus angle, facilitating bipedal walking, unlike chimpanzees who have a bent knee for their quadrupedal gait.
Step-by-step explanation:
Humans have a bent hip, unlike chimps who instead have a bent knee. The anatomical differences between humans and chimpanzees are significant with regards to locomotion. One of the most important anatomical changes for humans that facilitates bipedalism, or walking upright, is the angling of the femur inward at what is referred to as a valgus angle. This adaptation positions the knees and feet under the center of the pelvis and, along with the evolution of spinal curves, allows humans to balance the weight of the upper body while moving bipedally. In contrast, chimpanzees, which have a more protrusive jaw and a different locomotion pattern, rely on a bent knee that enables their quadrupedal gait. Additionally, bipedal hominins like Australopithecus sediba had humanlike spines and pelvises but retained a chimpanzee-like foot, indicating a transitional form of bipedalism.