Early hominins
Hominins are members of the human lineage after the split from the lineage leading to chimpanzees and bonobos (~7–5 million years ago). The earliest known members retained a mixture of ape-like and human-like traits. Bipedalism was one of the earliest changes, but it developed gradually while our ancestors remained capable climbers. Benefits of bipedalism included freeing the hands, efficient walking, better heat management and carrying things. They also show changes in teeth and jaws, suggesting shifts in diet and possibly social behavior.
Timeline
- ~7 million-6 million years ago: Sahelanthropus tchadensis lives in Chad; its forward-positioned foramen magnum may indicate an upright posture, although its degree of bipedalism is debated.
- ~6.2 million-5.8 million years ago: Orrorin tugenensis lives in Kenya; features of its femur suggest bipedalism while retaining adaptations for climbing; its diet was probably varied and largely plant-based.
- ~5.8 million-5.2 million years ago: Ardipithecus kadabba lives in Ethiopia; a toe bone provides evidence consistent with bipedalism.
- ~4.4 million years ago: Ardipithecus ramidus lives in Ethiopia; it was bipedal but remained an effective climber; its reduced canine sexual dimorphism may indicate changes in social behavior.
Happening elsewhere at the time
Nothing found.