Final answer:
The oldest evidence for hominins is the species Sahelanthropus tchadensis, dating back to nearly seven million years ago. The next oldest evidence includes the genus Homo, the Laetoli footprints, and species such as Ardipithecus, Homo erectus, and the Denisovans.
Step-by-step explanation:
The oldest evidence for hominins comes from the species Sahelanthropus tchadensis, with a skull known as "Toumai" dated to nearly seven million years ago. This discovery represents a significant find for understanding human evolution, featuring a mix of both primitive and evolved traits. Before this, the genus Homo was thought to have first appeared between 2.5 and 3 million years ago, with fossil evidence from species such as H. habilis and Homo gautengensis. Early bipedalism was indicated by the Laetoli footprints discovered by Mary Leakey, dated to about 3.5 million years ago and attributed to Australopithecus afarensis. Evidently, the study of hominins is a field enriched by various important fossil finds including Ardipithecus, Homo erectus, and the Denisevans, each contributing unique insights into our ancestral past.