Question

Focus on Ardipithecus ramidus and Australopithecus afarensis when answering the following questions:

1. Which hominin had the best arboreal capabilities and why? Focus on the foot.

2. Which hominins was the first to not just be an upright walker but an obligate biped (this means you have no choice but to walk on two legs)? Make sure you explain your answer.

3. Lastly, I would like you to give a short summary of the transformations in locomotor strategy that occur over time from Ardipithecus ramidus to Australopithecus afarensis.

Answer 1

1) Ardipithecus ramidus has the best arboreal capabilities. It was adapted for facultative bipedalism but it spent most of its time on trees. It had better arboreal capabilities which is related to the specific features like a grasping hallux or big toe adapted for locomotion in the trees. The foot  bones of the 'Ardi' skeleton indicated the presence of a divergent large toe combined with a rigid elongated mid foot and other reduced phalanges . The pelvis, also shows adaptations combining tree-climbing and bipedal activity.

2)   Australopithecus afarensis was the first hominins to not just be an upright walker but an obligate biped which had no choice but to walk on two legs because they lacked the hominin features like long phalanges and the toes which were required for the arboreal mode of life. Evolution didn't selected for these arboreal features rather they have pelvis articulation and feumar ( thigh bones) similar to humans, so they were the obligate biped.

3)short summary of the transformations in locomotor strategy that occur over time from Ardipithecus ramidus to Australopithecus afarensis are ad followed:-

A. ramidus was the hominin having better arboreal capabilities as they had long grasping toes, hallux and curved fingers for grasping the branches of tree. They were the earliest hominids that was somewhat adopted for the bipedalism but they can't walk long distances as it lacked the efficient structure. later on gradually, the environmental and the evolutionary changed brought so many modifications like the long toes curved fingers were not sleeted in A. afarensis. They gradually developed longer midfoot with smaller phalanges that were suitable and efficient for walking on the ground. wider pelvic bones with shorter illiac blades and longer femur added to this requirement and efficiency. Ar. ramidus pelvis bones are more like that of living apes, with long flared illiac boes, hamstring tuberosity pointing downward and longer ischium.