>Evolution “remembers” building blocks that increase fitness.  The building blocks that recur generation after generation are those that have survived in the contexts in which they have been tested.  These contexts are provided by (a) other building blocks, and (b) the environmental niche(s) that the species inhabits.
>There is actually an extensive hierarchy that is continually tested at every level.  At the lowest level are particular, short DNA sequences that make up the chromosome’s alleles.  A the next level are the alleles themselves, and at one level above that are combinations of alleles, the co-adapted alleles, that code for enzymes that work well together.  The Krebs cycle is an example of such a co-adapted set, remembered over hundreds of millions of years.
>The building blocks that we observe are, by and large, the robust building blocks.  The Krebs cycle is so robust that it occurs throughout whole kingdoms of organisms.
>Under this view, evolution continually generates and selects building blocks at all levels, selected combinations of established building blocks at one level becoming the building blocks of the next-higher level.
>Evolution continually innovates, but at each level it conserves the elements that are recombined to yield the innovations.  When a new building block is discovered at some level, it usually opens a wide range of possibilities because of the potential for new combinations with other extant building blocks.  Tremendous changes occur.  The genetic algorhythm, applied to rule discovery, mimics this process but with a much simpler syntax.
        
        Syntax  
a. The study of the rules whereby words or other elements of sentence structure are combined to form grammatical sentences.
c. The pattern of formation of sentences or phrases in a language.
2. Computer Science;  The rules governing the formation of statements in a programming language.
3. A systematic, orderly arrangement.
4. The grammatical rules of a language and the way in which words are arranged to form phrases and sentences.