who gave the theory of survival of the fittest
Survival of the fittest Herbert Spencer first used the phrase, after reading Charles Darwin's On the Origin of Species, in his Principles of Biology (1864), in which he drew parallels between his own economic theories and Darwin's biological ones: "This survival of the fittest, which I have here sought to express in mechanical terms, is that which Mr. Darwin has called 'natural selection', or the preservation of favoured races in the struggle for life."[1]
Social Darwinism Herbert Spencer's ideas, like those of evolutionary progressivism, stemmed from his reading of Thomas Malthus, and his later theories were influenced by those of Darwin. However, Spencer's major work, Progress: Its Law and Cause (1857), was released two years before the publication of Darwin's On the Origin of Species, and First Principles was printed in 1860.