Question

Discuss how the theory of evolution explains the unity and diversity of life.

Answer 1

The concept of organic evolution holds that all the various kinds of plants and animals which are now known have developed out of earlier types by completely natural, gradual but continuous changes during the passage of time.

Complete answer:
Evolutionary biology involves study of history of various life forms on earth. The study of evolution generally describes how the higher life forms of life have gradually arisen out of lower. It is a gradual orderly change from one condition to another. The principle of evolution implies that the development of an individual in the course of time through a gradual sequence of changes forms a simple to a more complex state. So all the different kinds of organisms that we see today have evolved from common ancestors over millions of years.
Observations reveal that different types of animals possess some common characteristics. For example, amphibians, reptiles and mammals have limbs for locomotion on land, birds have wings for flying and fishes have fins for swimming. A study reveals that limbs, wings and fins are formed on the same basic structural plan. All such examples are explained by considering that the diverse groups of organisms share a common ancestor from whom they have diverged and formed two different species. With the passage of time a single ancestral lineage has produced two or more lineage that diverged over a time. Such a process of change in the biological system is therefore called evolution.

Note: As a structure is the result of interaction of genes and effect of environment. Evolution is, therefore, a change from one condition to another in which genes and environment play an important role.