Final answer:
Charles Darwin posited that humans evolved from great apes and that bipedalism involved complex anatomical changes. The savanna hypothesis suggests bipedalism was an adaptation to a savanna habitat, with Homo erectus showing efficiency in bipedal locomotion almost equal to modern humans.
Step-by-step explanation:
Charles Darwin hypothesized about the origin of bipedalism as part of his broader theory of evolution outlined in The Descent of Man. He argued that humans are descended from other hominids like the great apes. Darwin's ideas led to the development of modern biological science and the understanding that the evolution of bipedalism required complex anatomical changes, like the angling of the femur, the evolution of spinal curves, and the realignment of the toe.
Some of the hypothesized advantages of bipedalism included the ability to free hands for tool use, improved energy efficiency, and better thermoregulation by exposing more of the body's surface to the environment. The savanna hypothesis suggests that bipedalism evolved as an adaptation to a savanna habitat. The concepts of the stance leg and step leg are central to understanding bipedal locomotion, with anatomical changes evident in early hominins indicative of this mode of movement.
The most striking evidence of early hominin bipedalism was discovered by Mary Leakey with the Laetoli footprints depicting a modern striding gait. Over time, hominin species such as Homo erectus developed anatomical features that made them nearly as efficient at bipedal locomotion as modern humans. These findings underscored the fundamental shifts in early human ancestors that facilitated upright walking.