<P> Interpretations of the phrase as expressing a theory are in danger of being tautological, meaning roughly "those with a propensity to survive have a propensity to survive"; to have content the theory must use a concept of fitness that is independent of that of survival . </P> <P> Interpreted as a theory of species survival, the theory that the fittest species survive is undermined by evidence that while direct competition is observed between individuals, populations and species, there is little evidence that competition has been the driving force in the evolution of large groups such as, for example, amphibians, reptiles, and mammals . Instead, these groups have evolved by expanding into empty ecological niches . In the punctuated equilibrium model of environmental and biological change, the factor determining survival is often not superiority over another in competition but ability to survive dramatic changes in environmental conditions, such as after a meteor impact energetic enough to greatly change the environment globally . The main land dwelling animals to survive the K - Pg impact 66 million years ago had the ability to live in underground tunnels, for example . </P> <P> In 2010 Sahney et al. argued that there is little evidence that intrinsic, biological factors such as competition have been the driving force in the evolution of large groups . Instead, they cited extrinsic, abiotic factors such as expansion as the driving factor on a large evolutionary scale . The rise of dominant groups such as amphibians, reptiles, mammals and birds occurred by opportunistic expansion into empty ecological niches and the extinction of groups happened due to large shifts in the abiotic environment . </P> <P> It has been claimed that "the survival of the fittest" theory in biology was interpreted by late 19th century capitalists as "an ethical precept that sanctioned cut - throat economic competition" and led to the advent of the theory of "social Darwinism" which was used to justify laissez - faire economics, war and racism . However, these ideas predate and commonly contradict Darwin's ideas, and indeed their proponents rarely invoked Darwin in support . The term "social Darwinism" referring to capitalist ideologies was introduced as a term of abuse by Richard Hofstadter's Social Darwinism in American Thought published in 1944 . </P>

How is the general understanding of survival of the fittest misleading