Question : We sometimes find the existence of following structures in human beings: (a) Occurrence of short tail in some babies (b) Presence of additional mammae in two rows down the front of the body of some persons (c) Power of moving pinna, or (d) Presence of very long and dense hair on the body. Why does this happen in some persons? Also, name the phenomenon involved.

Question : We sometimes find the existence of following structures in

1.	Question : We sometimes find the existence of following structures in human beings: (a) Occurrence of short tail in some babies (b) Presence of additional mammae in two rows down the front of the body of some persons (c) Power of moving pinna, or (d) Presence of very long and dense hair on the body. Why does this happen in some persons? Also, name the phenomenon involved.
Answer» Solution :The appearance of above characters in some PERSONS is DUE to the phenomenon of atavism (i.e., the reappearance of certain ancestral, not PARENTAL, structure(s) which has/have EITHER completely disappeared or greatly REDUCED).