The principles behind evolutionary computation were discussed as early as in the 50's, but the first models appeared in the late 60's and early 70's. These are "evolutionary programming" (Fogel, 1966, see [4]), "evolution strategies" (Rechenberg, 1973, see [5]) and "genetic algorithms" (Holland, 1975, see [6]).
These three models were very different at the time of
their creation. After twenty years of evolution, they remain very much
different, even if united under the generic term of EAs. They still compose
the basis of the work in evolutionary computation (along with other models
later derived from them).
Here is a short description of the three models, showing the possible variations
in the generic EA presented in the first section.
It should be noted that EAs are a generalization of these three models,
and were formalized long after they were first created.