Question

Which of the following is not atavistic in humans?
A. Tail in some babies
B. Enlarged canine
C. Six fingers
D. Dense body hair

Answer 1

Hint: An atavism is a miracle in which, after a moment of nonattendance, a phenotypic consistency returns in a living being. An atavism refers to a quality that, despite the truth that was present in its precursors, is absent in an individual's prompt antecedents.

Complete answer: The creation of simpler and less elaborate types of organisms from complex organisms can be described as retrogressive evolution. This approach reverses change, which includes the creation of structures from simple structures that are more complex, elaborate, and specialized. The mutation is characterized as the sudden discontinuous inherited variations that will occur in the species due to their genotypes changing permanently. In his book, The Mutation Hypothesis, published in 1903, Hugo de Vries proposed the mutation theory of evolution. It is possible to understand the presence of the above characters in some people on the basis that there is a tendency among animals, including humans, to evolve structures present in their remote ancestors. Atavism is the phenomenon involved.
For example, the reappearance of the ancestral characteristics in any human, tail in an infant, longer canine in man, the hair on face and body, etc., is an atavism. Other cases of atavism include long arm and abdominal nipples, division of horse splint bones, etc. The occurrence of six fingers is not atavism instead is a result of genetic anomaly.
Hence, the correct answer is C, i.e., six fingers.

Note: Atavism and vestigial organs are different. Atavism is the sudden reappearance of a certain ancestral but not a parental system, also known as reversion, which has either entirely vanished or significantly decreased. Vestigial organs are all those organs that have been functioning in their ancestors and related animals but are non - operational in the bearer.