Introduction

It is important to note that Darwin’s book “The Origin of Species by Means of Natural Selection” did two things. It summarized all of the evidence in favour of the idea that all organisms have descended with modification from a common ancestor, and thus built a strong case for evolution. In addition Darwin advocated natural selection as a mechanism of evolution.

Current Understanding

Biologists no longer question whether evolution has occurred or is occurring. That part of Darwin’s book is now considered to be so overwhelmingly demonstrated that it is often referred to as the Fact of evolution. However, the Mechanism of evolution is still debated.

Modern Perspectives

We have learned much since Darwin’s time and it is no longer appropriate to claim that evolutionary biologists believe that Darwin’s theory of Natural Selection is the best theory of the mechanism of evolution. The book aims to bring out the basic principles of genetics and the mechanism of organic evolution in the light of recent discoveries in molecular biology, keeping in view the requirements and limitations of the course.