One of the pillars of contemporary evolutionary biology is Charles Darwin's theory of natural selection. Despite being widely acknowledged and backed by a wealth of evidence, there have been challenges and criticisms voiced over time. The main challenges to the theory of natural selection include the following:
- Although it is believed that natural selection is the primary factor in the evolution of new species, it is now understood that mutation also plays a role in the evolution of new species.
- There is no clear clarification of the difference between somatic and germinal variations.
- The distinction between heritable and non-heritable variations, which must exist prior to any selection, is not explained by Darwin's theory. Neither is the origin of variations.
- The selection of useful variations is not always the case. An advantageous organ may develop to the point of over adaptation, which could be fatal to the individuals.
- Natural selection only acts as a directing or controlling force in evolution because it occurs after variation has taken place. It is not a creating or initiating force.
- The effect of use and disuse of organs is not explained.