Sunday 5 October 2014

Recent introductions to memes

A couple of introductions to memes were published recently:

Thanks to Brian and Dan for their efforts in this area. Brian's effort is longer and contains more controversial content. He offers a historical perspective on the development of memetics. One of the things he says is:

A “selfish meme” interpretation of a cultural universal, however, implies that it is maladaptive (harming fitness).

Of course selfish memes can and do harm fitness associated with their host's DNA. However, that isn't really part of the definition what "selfishness" is all about in this context. The idea is that selfish memes are in it for themselves. They behave as though they are self-interested - and as though they are indifferent to the fate of their hosts. That doesn't mean that they harm their hosts. For example, strawberry genes can be described as being "selfish". They (behave as though they) care about making copies of themselves - and not about any humans who might eat them. Does this "selfishness" on the part of the strawberry genes mean that they are bad for humans? No. In fact, strawberries are a health food.

Dan Zarella's article is also good. I'm still deeply critical of Dan's assertion that his "R0" differs significantly between cultural and organic epidemics, though. Both genes and memes can spread explosively and both genes and memes can reach saturation levels in their host population. What Dan is saying here is just wrong.

Dan says:

I’ve never found a meme with a sustained R0 above one. Given a large enough population and a long enough time, the R0 of every idea falls below one and the idea stops spreading.
This is not the normal meaning of r0. Here's how Wikipedia puts it:

In epidemiology, the basic reproduction number (sometimes called basic reproductive rate, basic reproductive ratio and denoted R0, r nought) of an infection can be thought of as the number of cases one case generates on average over the course of its infectious period, in an otherwise uninfected population.

Here r0 is a constant value. It doesn't change over time. That is because r0 is defined with respect to an otherwise uninfected population.

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