Final answer:
Humans and our hominin ancestors primarily exhibit bipedalism as their mode of locomotion, as seen in the anatomy of early hominins like Homo erectus and evidence from the Laetoli footprints. This transition to bipedalism allowed for new survival strategies including tool use.
Step-by-step explanation:
The mode of locomotion for humans and our hominin ancestors is primarily bipedalism. Early hominins like Homo erectus showed efficient bipedal locomotion and had anatomical features such as a broader pelvis, longer legs, and arched feet which aided in upright walking. While their cranial features remained distinct from modern humans, their post-cranial anatomy was well-adapted to bipedality. This evolutionary shift from arboreal to terrestrial life allowed hominins to traverse diverse environments and paved the way for the development of new survival tools and strategies.
Key fossil discoveries, such as the Laetoli footprints discovered by Mary Leakey, offer clear evidence of bipedalism in our ancestors. These footprints, likely made by Australopithecus afarensis, exhibit a modern striding gait similar to that of contemporary humans. The adaptation to bipedalism allowed hominins to free their hands for tool use, carry offspring, and may have improved their ability to thermoregulate. While all humans exhibit bipedalism, species like Homo naledi and H. floresiensis demonstrate a mix of primitive and modern traits that reflect varying adaptations to bipedal locomotion.