This is interesting:

http://en.wikipedia.org/wiki/Survival_of_the_fittest

Survival of the fittest is a phrase which is a shorthand for a concept relating to competition for survival or predominance.

Originally applied by Herbert Spencer in his Principles of Biology of 1864, Spencer drew parallels to his ideas of economics with Charles Darwin's theories of evolution by what Darwin termed natural selection.

The phrase is a metaphor, not a scientific description; and it is not generally used by biologists, who almost exclusively prefer to use the phrase "natural selection".