Can was probably the wrong word.

The "natural" method of change for genes is random change, with some selection acting afterwards.

Changes do occur randomly to memes, but when approaching an arbitrary meme, I generally feel >95% confident that it was, at some point, extensively and deliberately designed, and >75% confident that the deliberate design was the dominant influence on it. In addition, basically everybody who is passing on a meme tries to communicate it in the most effective way possible: so even when looking at a change, my prior is that it is almost always at least partially deliberate (a result of somebody reasoning that they should change it in a certain way) instead of accidental.

In addition, genetic evolution is much more advanced than memetic evolution: the most competitive organisms in the wild are all randomly evolved, yet almost all effective memes were artificially designed.