Question

Which of the following are NOT examples of atavism?

• A. The phalanges of horse
• B. Vermiform appendix
• C. Movement of pinna
• D. Human body hair

Answer 1

Answer: (B), (D)

The correct options are
B Vermiform appendix
D Human body hair

Atavism or reversion is the reappearance of a trait that was perhaps necessary at some point of time during the course of evolution, but have been gradually lost as it is no longer required. For instance, the horse generally exhibits a fused condition of its 3rd, 4th and 5th phalanges, which had been separate bones until a certain point of time during its evolution. If this separate condition reappears in the present day horse, it is considered to be a case of atavism. The vermiform appendix and human body hair are examples of vestigial organs.