Question

A baby has been born with a small tail. It is the case exhibiting …………
A. Retrogressive evolution
B. Mutation
C. Atavism
D. Metamorphosis

Answer 1

Hint: The theory of organic evolution is perhaps the most reasonable explanation to account for the astonishing diversity of life on earth. At the same time, absolute proofs in support of it are lacking. Even then, it is built up on a solid scientific foundation which is strengthened by convincing circumstantial evidence.

Complete Answer:
Evolution simply means a gradual change, or a step by step transformation from a simple or primitive to a complex or advanced state. The most basic or essential concept of evolution is the continuity of all natural phenomena, the concept that everything we see on the earth, or in space around us, has arisen out of the something that existed before it.

The process of evolution can be divided into two, namely inorganic evolution and organic evolution. The fundamental difference between the two is so radical that it is somewhat misleading to use the term ‘evolution’ to describe them both. Inorganic evolution applicable to changes and transformation in the non-living world, whereas organic evolution applicable to the changes and transformations in the living world.

Mutation: Mutations are the sudden, stable and discontinuous heritable changes in the genetic makeup of organisms, other than those changes produced by Mendelian segregation and recombination. They appear almost abruptly, without apparent intermediate stages.

Metamorphosis: It is the well conspicuous change in form from one stage to the next in the life of an organism. It involves abrupt change in the animal’s body structure through cell growth and differentiation. Example is change from caterpillar to pupa and from pupa to adult butterfly.

Retrogressive evolution: In this, an organism reduces the complexity in structure and begins to develop more advanced characters in addition to the primitive characteristics.

Atavism: It is the phenomenon in which a character reappears in an organism after a period of absence. A character which is not present in the immediate predecessors of an individual, even though it was existent in its ancestors. Baby born with a small tail is an example of atavism.

Thus, here the correct answer is C) Atavism.

Note: Embryology is an important source of evidence for evolution. Every sexually reproducing animal starts its life from a single cell, the zygote. Zygote develops first to blastula, then to gastrula and finally to an organism. This developmental history of an individual organism is known as ontogeny. It is similar in related groups, such as different groups of vertebrates.