Replicators v1
What are replicators
Replicators are objects that replicate (duh), and they are worthy of study for their applicability to questions of evolution.
According to Dawkins, replicators have three basic properties—longevity, fecundity and copy-fidelity. Longevity, Dawkins says, is not of a specific sequence of DNA itself, but rather of the information that the gene encodes. Fecundity means many copies are made. Copy-fidelity means the process must not be too messy and fuck the gene up too much.
Genes are replicators
Genes clearly git all three of these conditions, and as such are subject to evolutionary processes over time; although their copy-fidelity is high, mutations (as well as a changing environment) results in selection pressures that weed out different genes over time. And so because genes are replicators, genes evolve.
Necessary vs. sufficient
As Dawkins put forth in The Selfish Gene, there may be other objects that are replicators other than genes. He puts forth the notion of a meme as another example of a replicator that may exist.
Note how the general theory of replicators was borne out of biological evolution. As such, the three conditions of longevity, fecundity and copy-fidelity are clearly sufficient for a genetic replicator; but this does not mean that these three conditions are the only conditions that could lead to replicators.
Non-copying replicators?
DNA replication is a multi-step process. Simplifying dramatically, DNA splits into two before it replicates. Note here that there are two ways to model this:
- The DNA copies itself.
- The DNA turns itself into a set of other molecules. Two copies of the original DNA then emerge.
Although (1) is literally true, I argue that this abstracts the replication process to a point where “copying” appears to be the only operation where evolutionary dynamics can apply. But this, it seems, is not true.
As in our DNA example, it’s possible to see the process of copying as the replicator being turned into some different molecule(s), before turning back into two copies of itself.
In fact, it is only our human bias towards DNA that leads us to look at the process as “DNA replication” vs. “single-sided DNA replication” in the first place. We could look at the above process as the process which which a single side of a DNA strand copies itself into multiple single sides of DNA strands.
More General Sufficient Conditions for Replicators
So let us try to reformulate the definition of a replicator to capture this. A replicator is any thing that: longevity, fecundity and reproductive-fidelity.
Note the main difference here: reproductive fidelity vs. copy fidelity. The replicator might copy itself immediately, but it also might transform itself to some other replicator (replicator prime) before going back to the original replicator.
It also seems theoretically possible to have a “replicator” that never once returns to it’s original state, but where each step in its reproduction is in fact a new “replicator.” It does seem unlikely that such a thing would exist chemically, although there are some (really pretty) examples of some oscillating chemical reactions.
Relevance to memes
Memes appear to be replicators, but it also seems very likely that they reproduce through means other than imitation.
As a single example, the meme of the “replicator” that I reproduce and spread above is not being spread through simple copying here: the only imitated words are the definition in italics at the top of this document. Instead, I am spreading the meme of the replicator through a rejection (or perhaps a generalization) of its core argument!