If evolution amongst memes really was responsible for, say, Rick Rolling, then we should expect to see a relatively continuous sequence of memes in historical records, analogous to the fossil record.
Maybe. The fossil record is patchy - and not always accessible - and much the same is true of culture. In practice, it's often possible to make valid inferences even if you have no fossils. If you see an organism, you can validly assume it has an evolutionary history - even if you have no fossils - simply because of common descent. We can often do much the same thing with memes.
The term “meme” has found widespread use in contemporary discourse, especially when discussing the public mindset, since the constitution of that mindset is what memetic evolution is supposed to explain. It is often used to refer to particularly catchy or trendy ideas, but I have argued that in many such cases there is little justification for assuming that an evolutionary process was responsible. Questioning whether the term “meme” should be applied in such cases process is dangerously close to a vacuous quibble over semantics; however, a few cautions do bear mentioning. First, it is a mistake to think that a deeper understanding has been reached just by calling something a meme. In the absence of evidence for an evolutionary process, calling something a “meme” is no different to calling it an “idea” or “phrase”. No greater understanding of its nature or origin has been reached by invoking the term, nor does the term suggest any new ways that it might be manipulated, magnified, or minimised.Alex seems to think that you shouldn't call some aspect of culture a 'meme' if you can't back up your assertion with a memetic fossil record - showing competition and selection between memes. That goes to the definition of a meme - and I don't think the dictionary agrees with Alex. Here's what one dictionary says for "meme":
an idea, behavior, style, or usage that spreads from person to person within a culture .
an element of a culture or system of behavior that may be considered to be passed from one individual to another by nongenetic means, especially imitation.
These definitions don't rule out memes that pop into existence by chance, or memes that are intelligently designed. The whole idea that the term "meme" implies an origin involving competition and selection between a series of evolutionary precursors seems to be contrary to how the word is commonly defined.
Alex is correct to say that calling something a 'meme' doesn't imply that it wasn't intelligently designed. However, that's simply a matter of definition. I don't see how it is a 'problem' - and I don't see why Alex calls it a 'problem'.
Alex closes with:
In this essay I have argued that although memetic evolution is a coherent concept, applying it as an explanation for specific phenomena requires extra evidence to corroborate its causal role in producing those phenomena. In the absence of such evidence we should be careful about using the term “meme” too liberally since we may make unjustified assumptions about the nature of the ideas we are dealing with.The "unjustified assumptions" Alex is referring to is the assumption of an evolutionary history involving variation and selection. However, this assumption seems to be coming from Alex - not from memes or memetics. It is OK to have intelligently-designed memes - indeed the internet is full of them.
In summary: we can legitimately use the term "meme" liberally - if we simply adopt the standard definition of the term. I think Alex's concerns about "unjustified assumptions" are themselves unjustified.