Final answer:
Evidence for hominin ancestors dates back to at least 5 to 10 million years ago, with early species like Ardipithecus dating to around 4.4 to 5.6 MYA and the first appearance of the genus Homo between 2.5 and 3 MYA.
Step-by-step explanation:
Evidence for hominin-like ancestors dates back to at least 5 to 10 million years ago (MYA) in the late Miocene epoch. Specifically, notable species such as Ardipithecus ramidus and A. kadabba provide insight into very early hominins with dates around 4.4 MYA and 5.6 MYA, respectively. Meanwhile, the genus Homo appeared between 2.5 and 3 million years ago, with early homo species like H. habilis showing attributes more similar to modern humans.
One of the most profound discoveries regarding the evolution of bipedalism was made by Mary Leakey in the 1980s with the Laetoli footprints, dating to about 3.5 MYA and likely made by Australopithecus afarensis. These footprints suggest that early hominins had already developed a bipedal mode of locomotion. Furthermore, findings such as the Petralona cranium, with traits of both Homo ergaster and anatomically modern humans, indicate a complex interspecies evolution over hundreds of thousands of years.