Question

We sometimes find the existence of following structures in human beings :
(i)occurrence of short tail in some babies
(ii)presence of additional mammae in two rows down the front of the body of some persons
(iii)power of moving pinna,
(iv)presence of very long and dense hair on the body
Why does this happen in such persons? Also , name the phenomenon involved

Answer 1

The appearance of above characters in some persons can be eplained on the assumption that there is a tendency among the animals including human beings to develop structures that were present in their remote ancestors .
The phenomenon involved in called atavism (i.e., the reappearance of certain ancestral, not parental, structure(s) which has/have either completely disappeared or greatly reduced )