Question

1) What anatomical changes in the hindlimbs/vertebral column of hominins occurred that allowed them to locomote bipedally?

2)Primate evolution may be characterized by a series of adaptive radiations. Define the concept of an adaptive radiation and provide an example from primitive evolution.

Answer 1

Evolution to bipedal movement from quadruped movement involves lots of anatomical changes.

The first and most important is changes in the hip joint. In quadrupedal ancestor the hip joint is smaller as compared to bipedal organisms. This broadening of hip joint has resulted in providing more support to erect structure and played an important role in providing balance while walking.

Further to this knee joints in humans get enlarged to ensure they can support weight of bipedal moving organisms. Limbs have evolved to support a forward movement. In humans the limb muscles support forward movement at ankles. The joints have evolves to ensure they can bear the strain of brisk walking by developing bigger in size. Vertebral column also got adjusted with bipedal movement. The vertebral column is curved at Lumbar and Thoracic region providing ample of support while walking.

Adaptive Radiation can be defined as a process in which an organism gets diversified from its ancestral species into multiple new forms. Adaptive radiation is particularly important in scenarios where changes in environment has results in availability of new resources.

One example of adaptive radiation could be evolution of beaks of finches found in Galapagos islands. Out of 14 finches, 04 have developed different beak shapes due to change in food sources. The beaks has adapted to the available food sources.