Synopsis of my replicator critique

For most traditional meme enthusiasts, memes are "the new replicators" - or are practically defined in terms of the Dawkins replicator-vehicle framework. I'm reasonably convinced by the critics that this is an unsuitable foundation for a general purpose evolutionary framework.

I've gone into this in a video/essay Against Replicator Terminology and in my 2011 memetics book, but here's a handy synposis:

Part of the problem is terminology. Dawkins (1976) defined "replicator" as follows:

"A replicator is anything in the universe of which copies are made."

One issue (1) is the "replicator"-"replicatee" distinction. You would think the appropriate term would be "replicatee" - and "replicator" would be the thing doing the copying.

Another issue (2) is copying fidelity. The "replicate" term suggests high fidelity copying. The corresponding term without that implication is "reproduce". A replica is normally a type of high fidelity reproduction. The Dawkins definition steamrollers over this distinction.

These are terminology criticisms - but my last critique is scientific - rather than just being about what words refer to which meanings. The "replicator" terminology suggests a modeling framework in which two inheritied entities are either idenitical or different. It represents a kind of binary view of inherited information. That works quite well for advanced systems of herediy because those have evolved to be digital. Nucleic acid and language are both basically digital systems which involve and use redundancy and error correction to avoid contamination by noise. However, not all systems involving inherited information are like this. In particular some of the systems I am interested in are those which exhibit Darwinian family trees in a more-or-less analog media. For example, electrical discharges, propagating cracks and fractal drainage patterns. These exhibit copying (of position and other attribuutes) with variation filtered by the environment, and a good number of Darwinian models apply to these systems. However the replicator-vehicle framework seems pretty irrelevant to their study. This consideration has the effect of displacing replicators from the foundation of Darwinism. They are still applicable to more advanced systems with error detection and correction, (but see points 1 and 2). As students of cultural evolution sometimes point out, not all cultural inheritance involves error-corrected systems such as language.

My personal preference is to just grant this point to critics of memetics and move on. The "m" word is still pretty useful, replicator terminology aside.

Repology 101: Copying is ubiquitous

Copying is everywhere in biology. It is most obviously seen in DNA replication. Electrical signals are copied inside brains whenever an axon branches. Ants copy each other's paths by following pheromone trails. Copying is also the foundation of all human culture. It's reached a zenith inside computers and on the internet.

What is less widely appreciated is that copying is also ubiquitous in inorganic, non-living systems. Ripples, flame propagation, crystal growth, electrical discharges, propagating cracks, and photons hitting dust all involve copying. Copying is a fundamental part of physics. It is built into the fabric of physical law.

While there's been a science that studies copying (and some other things) in living systems (genetics) there's been little or no scientific focus on copying outside biology. It has been a dark area of science.

Repology 101: Repetition

It would be quite nice to say that repology is the science of copying - covering reproduction, replication and repetition. However, repetition is a bit of an odd-one out here - it doesn't necessarily involve copying.

Of course many types of repetition do involve copying. Any type of repeating voluntary animal behaviour, for example, involves repeated copying of information from memory neurons to motor neurons.

However, there are some types of repetition which do not involve copying - for example: spinning objects repeat their earlier configurations repeatedly - yet typically nothing is being copied during the process.

The phenomenon of repetition brings the domain of repology into question. The term 'reps' is often used as an abbreviation for 'repetitions' - raising the question of whether repology should include repetition.

I think we are better off with repology being the science of copying. Copying if of significant scientific interest - since it is part of the foundations of genetics and evolutionary theory. Repetition that doesn't involve copying seems to be a quite different topic. I think it is worth excluding it.

Repology 101: reps

An early contribution to repology took place in 1976, when Dawkins introduced the concept of a "replicator" to biologists. In 1982, he wrote:

I define a replicator as anything in the universe of which copies are made.

The "replicator" terminology has gone on to be popular, but controversial. The controversy centres around the issue of the ordinary English term "replicator" strongly implying high-fidelity copying, while Darwinian evolutionary theory doesn't require high-fidelity copying in order to work - according to standard information theory - e.g. see John Von Neumann (1952) "Probabilistic logic and the synthesis of reliable organisms from unreliable components".

Repology is based instead on the "rep". A rep is defined as follows:

Rep: anything that has been copied from something else

High-fidelity copying is emphatically not implied. Instead, copying fidelity is an attribute of the rep. High-fidelity copying is not a defining trait.

Note that the definition differs from the Dawkins definition of "replicator" is that the child is the "rep", while the parent is the "replicator". Whether an entity is an ancestor can change during the course of their lifetime, while an offspring is always an offspring. Once a rep, always a rep. DNA sequences in mules are "reps", but they do not fit the definition of "replicators" - since they are never copied from.

Reps differ from a generalized version of the concept of "gene" - since you can have inheritance and heredity without copying. If we take "gene" to refer to the basic unit of heredity, this need not refer to a copied entity. For example, I inherited my grandfather's clock. However, I didn't copy it. Reps are not the basic unit in a science of heredity.

Having side-stepped the controversies associated with the replicator concept, repology should be able to put the science of copying on a firm foundation.

Repology

I've long been sceptical about whether a science of copying could compete against genetics - or even find much of a niche in its presence.

However, I've now changed my mind about its potential viability. In particular, I've previously lamented the lack of a science of copying. Saying that the topic is part of information theory doesn't really cut it.

Since I think naming things is important, one of the things I've looked for is a name for the science of copying - and now I think I've found one: "repology".

Repology is the science of reproduction, replication and copying.

By "copying", I mean what it says in the 2013 article: What are inheritance and copying? Basically, copying involves information in one place spreading to multiple locations. It has two essential elements: Shannon mutual information and causality.

A science of copying isn't the same thing as a science of heredity. In particular, heredity consists of other means for patterns to persist besides copying - including: longevity and resisting modification. However, copying is an important component of heredity.

In terms of the Dawkins trinity (of fidelity, fecundity and longevity), repology is the science of fecundity - whereas heredity involves all three components.

My hope is that the term "repology" will be acceptable to both advocates and opponents of the replicator terminology promoted by Dawkins, Hull and Szathmary.

To dismiss a possible objection immediately, no implication that the reproduction, replication or copying involved are "high fidelity".

Repology does have some advantages over genetics. In particular, it doesn't come with useless historical baggage linking it to nucleic acids, or confining its domain to biology. It is unencumbered by such nonsense.

The most significant criticism of repology seems to me to be the idea that is is essentially the same thing as the science of heredity (i.e. a generalized version of genetics). Yet, fidelity, fecundity and longevity are somewhat different topics - and there are some benefts from a more fine-grained approach.

Repology hasn't seen very much action so far - but I'm hoping that giving the field a name will help a little with that.

References

• Tyler, Tim (2014) Repology 101: reps
• Tyler, Tim (2014) Repology 101: repetition
• Tyler, Tim (2014) Repology 101: Copying is ubiquitous