The Free On-line Dictionary of Computing (30 December 2018):

evolution strategy

   (ES) A kind of evolutionary algorithm where individuals
   (potential solutions) are encoded by a set of real-valued
   "object variables" (the individual's "genome").  For each
   object variable an individual also has a "strategy variable"
   which determines the degree of mutation to be applied to the
   corresponding object variable.  The strategy variables also
   mutate, allowing the rate of mutation of the object variables
   to vary.

   An ES is characterised by the population size, the
   number of offspring produced in each generation and whether
   the new population is selected from parents and offspring or
   only from the offspring.

   ES were invented in 1963 by Ingo Rechenberg, Hans-Paul
   Schwefel at the Technical University of Berlin (TUB) while
   searching for the optimal shapes of bodies in a flow.

   (1995-02-03)