Richard Dawkins first introduced the word in The Selfish Gene (1976) to discuss evolutionary principles in explaining the spread of ideas and cultural phenomena. He gave as examples melodies, catch-phrases, and beliefs (notably religious beliefs), clothing/fashion, and the technology of building arches.
But like a good deal of Dawkins' thinking, 'memes' is not actually science, but philosophy. Dawkins likes to promote evolution as the total answer to everything, and in the process has come up with this piece of philosophical nonsense that, while it might explain something we already know (ideas catch on), isn't actually science in any sense.
Regrettably, he has a number of disciples who plainly believe that 'memes' actually mean something. Susan Blackmore appears to be a prime example.
In the 31st July edition of New Scientist, (that most evolutionary-minded of all magazines) she has written an extraordinary piece in which she proclaims the following 'scientific' thinking:
What do I mean by "third replicator"? The first replicator was the gene - the basis of biological evolution. The second was memes - the basis of cultural evolution. I believe that what we are now seeing, in a vast technological explosion, is the birth of a third evolutionary process. We are Earth's Pandoran species, yet we are blissfully oblivious to what we have let out of the box.Along with Dawkins, she thinks that genes have a mind of their own, and that memes (which didn't exist until Dawkins dreamt them up) have a similar ability to hop from human to human and do their own thing.
What does the following actually mean? This might sound apocalyptic, but it is how the world looks when we realise that Darwin's principle of evolution by natural selection need not apply just to biology. Given some kind of copying machinery that makes lots of slightly different copies of the same information, and given that only a few of those copies survive to be copied again, an evolutionary process must occur and design will appear out of destruction. You might call it "design by death" since clever designs thrive because of the many failures that don't.
She then goes waffling on about humans being 'lumbering robots' (Dawkins said so, so it must be right) that genes have built to carry them around, propagate them and protect them. Her article is a fanciful piece of stuff that is basically being made up as it goes along. It's pure speculation given some respectability by being published in a well-known magazine, one that often does have some real science in it.
The third replicator, of course, is technology, specifically the Internet, where apparently, according to Bradshaw, "We should also expect design to appear spontaneously, and it does. Much of the content on the web is now designed automatically by machines rather than people."