The really great memes* don't just emerge by chance. They have to be thought of, discovered, invented, created; not necessarily intentionally, or purposefully, but certainly recognised as valuable, either by the meme-originator or meme-copier.
And surely many of those early world-changing memes are things that can't be half-invented or discovered bit by bit. Like how to make fire, for example.
From a meme-perspective, it's hard for us to imagine what it must have been like for early memes. At that time our ancestors were animal-smart, instinctive creatures, probably living much as we see modern higher primates: social groups of chimpanzee or gorilla. Then development was slow, driven by gene- rather than meme-evolution. But there must have been a cusp, a point in evolutionary time when memes start to take hold and gene-meme coevolution starts up. How long was that cusp? Thousands... tens of thousands of years, perhaps.
Think of that period. There must have been countless instances when one smart individual in a group hits upon something useful, but for any number of reasons that discovery dies with its creator. Take fire-making, as an example. Perhaps none of the other individuals in the group are smart enough to recognise the value, or utility of fire-making. Or, worse-still, they are so terrified of the fire-maker's magic that they banish or kill the unfortunate innovator. Alternatively, there may be one or two individuals who do see that this is not something to be feared, but valued. But what if they're just not smart enough to be able to mimic the actions of the fire-maker? To propagate, memes need meme-copiers just as much as meme-originators, and so the fire-making recipe is lost because no-one can copy it. Now consider the larger context. Imagine that one tribe has learned fire-making, and is able to refine and pass the technique from one generation to the next. But then another tribe, larger and stronger, wipes out the fire-maker tribe because of fear, or envy. Or they get wiped out anyway because of famine, or any number of other natural disasters.
Life was precarious then, and so it was for memes too. My point is that many memes were probably thought-of, discovered or created, only to be lost again. Then a few hundred or few thousand years passes before they are thought-of all over again. How many times over did those early memes have to be re-invented before they finally found a foothold and became so widespread that only a major catastrophe affecting the whole population would threaten the meme?
One reason, I think, that this is hard for us to imagine (and construct models of), is that we are used to living in a time when life is easy for memes. Too easy perhaps. We are all surrounded by unbelievably expert meme-copiers. Indeed human beings have become so good at it that meme-copying is surely something that now characterises us as a species. Modern society, from a meme-perspective, is a rich and fertile substrate in which even the most inconsequential memes can thrive (like mobile phone ring-tones).
But it wasn't always so.
Life was tough for early memes.
*For internet definitions of 'meme' see Google define: meme
And for Susan Blackmore's longer description click here.