Final answer:
The idea that bipedalism evolved as an adaptation to open savanna habitats is known as the savanna hypothesis. It suggests that bipedal locomotion provided hominins with the ability to see predators and travel efficiently in these environments.
Step-by-step explanation:
The idea that the shift to bipedalism was a response to living in an open habitat such as the savanna is based on the concept known as the savanna hypothesis. This hypothesis suggests that many human traits, including upright bipedal locomotion, evolved as adaptations to this type of environment. One of the benefits of bipedalism is that it allows a hominin to see over tall grasses to watch for predators, and it is also an energy-efficient form of locomotion over the long distances that characterize savanna environments.
Early hominins like Australopithecus afarensis, evidenced by the Laetoli footprints found by Mary Leakey, demonstrated a modern striding gait indicative of bipedalism around 3.5 million years ago. Homo species, such as Homo erectus, had anatomical adaptations conducive to bipedal locomotion, like a wider pelvis, longer legs, and arched feet that emerged later in the human lineage. These adaptations imply that early hominins were capable of efficient bipedal movement, which may have conferred advantages in the savanna habitat where they could have encountered diverse survival challenges.