That's Darwin's natural selection . New variants always preferentially occur around the more successful of the current patterns. This is what Darwin later called an inheritance principle. So recursion keeps exploring the solution space, finding peaks in the adaptational landscape. There are another five features that, while not essential for the recursive boostrapping of quality, still notably influence the rate at which progress is made.
Variants happen, but they're either nonviable or backslide easily.
But there are four catalysts. The pioneers that rediscover the niche get a series of generations with no competition, enough resources even for the odder variants that would never grow up to reproduce under any competition. Small molecule drug screening strategies now can use a Darwinian sieve. This allows fractional percent differences in function to be amplified over a number of generations into two-fold differences in function. So keep an eye open for patterns that can be copied with variations, where competition can then occur between variants.