Ardipithecus ramidus

Ardipithecus ramidus

Ardipithecus ramidus dated nearly 4.4 million years ago, and it is located in Awash River Valley in Ethiopia. Key features of the Ardipithecus ramidus include the following;

  • They have thin enamel, most importantly the only hominin with a thin enamel.
  • They have a small brain capacity
  • They had an average of 120 cm in height
  • They have a curved foot phalanges
  • They do not have perihoning
  • They have teeth and postcranial bones

Having the above characteristics, the Ardipithecus ramidus indicates that they were arboreal hominins that displayed bipedalism traits. Such trails suggest that humans might have had Ardipithecus ramidus as part of their ancestors (Larsen).

Some of the changes that occurred to the anatomical figures in bipedal hominin include the following

  • Loss of four legs to walking and balancing with two legs. This came along as the legs increased in lengths and the forelimbs decreased in length.
  • Their hands lost the grasping abilities as well as part of their legs. This came along as the primates migrated from the woodlands to the grasslands; meaning that they could no longer grasp on trees in the forests.
  • They possessed enlarged heels while having reduced toes that would facilitate bipedalism.
  • Their femur bone characterized by becoming medially angled to support the now bipedal homonym to be able to stand without tiring.

The hypothesis that explains a change to bipedalism is due to the changes in the forest covers. In turn, due to the patchiness of the forests, food became scarce and dispersed; meaning that they would use their arms to collecting the available food (Larsen).


Larsen, Clark Spencer. “Our Origins: Discovering Physical Anthropology.” Early Hominin Origins and Evolution. New York: W. W. Norton & Company, 2017. 282-327. Book.