This chapter discusses evolution which has happened in the past, and is happening now. It explores a glance at human evolution, and to see how man differs from the other mammals, his nearest relatives, and how these differences have arisen. The human brain has two super-animal activities, manual skill and logical thought. Manual skill appears to be the earlier acquisition of the two and the capacity for language and thought has grown up around it. A biologist can do two things besides discovering facts, such as the facts of human evolution and genetics. The Nazis degraded most of the German people morally, and brought death and misery to a whole continent. Their biological ideas were grossly incorrect. Human polymorphism certainly extends to innate abilities as well as physical and chemical characters such as stature and hair colour. The Indian caste system was an attempt to divide society into a set of reproductively isolated groups each with its peculiar function.