Who popularized the phrase 'survival of the fittest'?

While often mistakenly attributed solely to Charles Darwin, the enduring phrase 'survival of the fittest' was actually coined by English philosopher and sociologist Herbert Spencer. He first introduced this concept in his 1864 work, *Principles of Biology*. Spencer developed his ideas after reading Darwin's groundbreaking *On the Origin of Species*, published five years earlier.

Spencer used 'survival of the fittest' to encapsulate a principle he saw at work in both the natural world and human society. He believed it was a succinct way to describe what Darwin referred to as "natural selection," drawing parallels between biological evolution and his own theories on economics and social development. Interestingly, Darwin himself later adopted Spencer's phrase, incorporating it into the fifth edition of *On the Origin of Species* in 1869, influenced by a suggestion from Alfred Russel Wallace.

Spencer's application of evolutionary ideas to society laid the groundwork for what became known as "Social Darwinism," a philosophy suggesting that individuals and societies succeed or fail based on their inherent "fitness." While Darwin focused on an organism's ability to adapt and reproduce in its environment, Spencer's interpretation of "fittest" often extended to notions of individual and societal superiority, shaping significant, and often controversial, discussions about social progress and competition.