Meme Machine

I've just watched Susan Blackmore giving a talk at TED, prompted by a New Scientist article. In it she effectively proposes that what makes us human is that we are mimics. In fact our ability to mimic others is so extraordinary that we have become the progenitors of another form of life.
But I have one niggling doubt about her hypothesis and the idea of evolution in general, and that is: how is it possible to distinguish a replicator that is blind and lucky and one that actively ensures its own survival?
Take the meme for a two pence coin for example. Clearly, it has been quite successful. There are probably millions of them in circulation and they fulfil their 'function' very well. Of course the physical coin is only an embodiment of the meme (the same way we are embodiments of genes); but we can use the coin as a proxy for the meme.
So how can we tell if the two pence coin actively ensures its own survival, to be passed down its generations, or has just been lucky enough to survive this long? In other words can we tell if the meme for a two pence coin has a directed purpose?
Firstly, we have to distinguish being lucky from having a purpose (to make sure it replicates). For example a piece of 3.5 billion year old rock just dug up from the ground, has probably just been lucky to have stuck around for so long. What about the chemical reaction that started life all those billions of years ago? Now we're not so sure, luck has undoubtedly played a part, but there must be something else that keeps the life replicators alive through the ages. In a word: feedback.
More specifically feedback with the replicator's environment. The replicator tips the survival odds in its favour by affecting the very thing that produces those odds, its environment. Now it becomes simpler to see how this could evolve, as any replicator necessarily uses resources from its environment in order to reproduce itself. This forms a feedback loop which the replicator can use to its advantage. Note that the replicator doesn't initially actively set out to change its odds of replicating, it just gets lucky with one of its feedback loops.
And this is my main niggle with the way evolution is portrayed, in that an organism (replicator) becomes as fit as possible in its niche over its evolution. It's not the whole story, the whole story is that the replicator changes it's niche because it's stuck in a feedback loop with it. So in a sense the niche becomes fit to the replicator.
So where does this leave our humble two pence coin? For sure, the meme has affected millions of humans (its environment) and we all buy into the delusion of what it can do for us and what it stands for.

May it live long and prosper.