Memes are like societal mind viruses, they can infect the cultural zeitgeist, mutating and replicating with every utterance in whatever social eddy they may drift. Slogans, tropes and limericks can change the societal direction.
Taken to the extreme, memes can become integrated into the permanence and replicability of the human genome through the standard paradigm of isolated interbreeding populations. Take as exemplari gratis, the physical differences between species of animals, begin as location memes that are then ensconced in DNA, the Camel vs the goat: water conservation vs Alpine rock scaling. Or rabbits and elephants, totally different reproductive strategies (r vs. K)..