Talk:Self-replication

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I added a line mentioning memes, and then a few minutes later someone else removes it with no explanation. In what way are memes not relevant to an article on self-replication? Bryan Derksen

I did not remove the sentence, but perhaps someone removed it because the article is about real things that self-replicate, and memes are not real things but rather either 1) a metaphor or 2) an analytic construct based on a particular theoretical model. Cells are material things that can be observed objectively. Memes are not material objects, they are ideas. SR
But then why are Computer viruses still included? Memes may not be "physical," but they have tangible characteristics that can be studied in an objective manner. See, for example, the paper linked to from the Chain letter article. Bryan Derksen
The title of the article "self replication" refers to the abstract concept, not about any manifestation thereof. It is wrong to remove reference to any given manifestation from the article but, it is not wrong to separate the concept from the example manifestation. Put "meme" and all other examples in an "Examples" section. William R. Buckley 20:10, 24 November 2006 (UTC)

I agree--ideas may not be "material" things, but they're certainly "real" by any reasonable definition of that word: they have physical expressions and physical effects on the world. Things like musical tunes and scales, languages and idioms, methods of doing things from cooking to business, games, holidays, and many other things have distinct effects on people's lives. --Lee Daniel Crocker

Fair enough. But why then use the word "meme?" Why not use the more common, but apparently equally appropriate, words "thoughts" or "ideas?" SR
For the same reason I wouldn't use the word "chemicals" when I'm talking about genes; meme is a specific technical term that applies to the specific type of thought or idea that is relevant to the concept of self-replication. Bryan Derksen
Fair enough -- but honstly, I am still unclear: is a meme a class of ideas, or is it a complex and organized set of ideas, the whole being greater than the sum of its parts (you seem to be suggesting this)? I went to the "meme" article and frankly do not feel that it answers my question, and explains this, clearly. Perhaps you will have time at some point to develop that article to make this clearer, SR
I wrote the bulk of that article, and I tried to be as clear as possible while sticking to the original meaning of the term and not the wild extrapolations people are prone to heaping on it. It's really quite a simple idea--a meme is simply an idea that gets passed on, possibly in mutated form, from one person to another. They can be as simple as things like handshakes and bows, or as complex as Catholicism.
Taking a look at it now. I think the key concept of a meme is that it is a "unit" of thoughts/ideas that is passed on as a single entity, such that subdividing it results in something that isn't "functional." This is an analogue to how a gene is a unit of heredity; a single gene encodes some characteristic, and groups of genes can encode some characteristic, but "half a gene" doesn't do anything and isn't even particularly meaningful as a concept (half of a gene's DNA sequence may be meaningful and functional, but that's not what pure theoretical genetics is focused on). For example, the idea "green M&Ms are aphrodisiacs" is a meme; it gets passed around as an urban legend among people. But the idea "green M&Ms" isn't a meme, or at least isn't a particularly _functional_ meme, because it doesn't get passed along as a self-contained unit. You may get people standing around water coolers and saying "by the way, have you heard that green M&Ms are aphrodisiac?" to each other but you don't get them saying "by the way, have you heard of green M&Ms?"
Hope that little ramble was helpful, and accurate. :) Bryan Derksen
Well, this is very helpful -- but still unsatisfying. It sounds like you are talking about a "proposition." At least, this is the term people have beenusing to refer to things that people think that are passed along as a single entity, which can be subdivided into different parts (e.g. facts) although those parts do not convey the meaning (or have the function) of the proposition. If I understand you correctly, it seems kind of silly to invent a new word to replace a very good word that people have been using for thousands of years. If youmeans omething different, I guess I still need clarification. SR

I originally removed the line because I believe that meme theory is not currently a scientifically accepted theory. I may be wrong. Also while a meme (such as the chain letter) might be "replicated", there is certainly no way that it can be "self-replicating". It can take no action of itself. No matter how long that chain letter stays in my wastebasket it will only remain one letter, not become several. --rmhermen

You are mistaken; some aspects of memetics are very speculative, and not taken seriously by many scientists. But one could say the same of psychology or astrophysics. The basic concept itself, that ideas can be self-replicating, is almost tautological, and not really subject to doubt. It is the often wildly extrapolated consequences of that fact that gives memes a bad name in some circles, but good peer-reviewed journals of memetics exist, and certainly Dawkins himself is the very paragon of "serious" science. --LDC

Even if I stretch the idea of self in self-replicating to include chain letters because they contain in appeal to replicate them in their text, somewhat similar to the code in a computer virus, I don't understand how an ordinary simple idea, like the "green M+M's are aphrodisiac" above, can be "self"-replicating. Certainly replicated and replicatable but how is it self-replicating? --rmhermen

The M&M thing resulted from a digression on the subject of what memes are, not what self-replicating things are. I never intended for it to be taken as an example of a self-replicating meme, it's just an idea which forms a "unit." Bryan Derksen
There are memes, which are individual ideas which can be replicated (with a chance of mutation) between retention systems (i.e., "It's wrong to use birth control."), and meme complexes, groups of interdependent memes which are passed on more or less as a group (i.e., Catholicism). Memes and meme complexes are best exemplified by the phrase "monkey see, monkey do": one retention system (a human, for instance) communicates an idea or a set of ideas to another retention system, either by language or demonstration; the other retention system decides whether or not it's a worthwhile meme, and either discards it, mutates it, or internalizes it, generally based on the perceived benefit of the idea (Green M&M's cause mating; mating is good). The meme or meme complex then is subjected to natural selection and, on the aggregate, either flourishes or dies off. Some (like Catholicism) flourish because they are prone to reproduction; others (like the Heaven's Gate cult) die off within a single generation, just as a genetic defect which causes the host to die before reproduction would die off in a single generation. THERE! :-D --pluggo 09:19, 10 February 2006 (UTC)
Viruses and computer viruses also cannot replicate entirely on their own, but they do cause their own replication when placed in the right environment. This applies to things like animals, too; a mouse will not replicate without a constant supply of oxygen and food chemicals, yet there's no significant debate over whether a mouse should be called self-replicating. Basically, it's all a continuum, with no clear-cut dividing line.

Like rmherman, I too am confused. Ar you using "self-replicating" to refer to ANY form of reproduction that is not "sexual reproduction?" Is a Chevy Impala, rolling off an assembly line, self-replicating?

What I'm saying is that there is no way to draw an absolutely clear line between the set of all things that self-replicate and the set of all things that do not self-replicate. Yes, there are clearly some things that can be called self-replicating; cyanobacteria, etc. And there are some things which are clearly not self-replicating, such as a chunk of rock. But between those two extremes, things get fuzzy. A Chevy Impala is not self-replicating in the same sense that bacteria self-replicate, if you stick one in a field next to a pile of iron ore and come back a year later there's still only going to be one Chevy Impala. But it might be called self-replicating in the memetic sense; if you drive your Chevy Impala around town and lots of people see it and like it and order their own from Chevy, then that Chevy Impala has in a certain sense used humans as a tool to make more copies of itself. You can't separate something from its environment when considering whether it's self-replicating or not. By the same token, organisms that reproduce sexually can and usually are considered to be self-replicating, because one generally considers them as a population rather than as a collection of isolated individuals. A population of mice is self-replicating even though a single mouse on its own will die childless. A virus inside a host is self-replicating, even though in isolation it's chemically inert. Even a simple inorganic crystal can be considered self-replicating under the right circumstances; smash it to bits and drop the bits into a supersaturated solution, and soon you'll have a whole bunch of crystals similar in size and nature to the original crystal growing from the various bits. This last example is, of course, way out near the "non-self-replicating" edge of the continuum, but still in the grey. Bryan Derksen
Okay, this is interesting, but it seems to me that it is not the Chevy Impala that is replicating, but the desire for Chevy Impalas or the idea of driving a Chevy Impala. I am still not clear what is gained by calling this "self-replicating" rather than "replicating" -- espcialy since "replicating" alone allows one to consider the social proceses through which such replication occurs. You mention that a population of mice is self-replicating, but populations are socially interactive, so here you allow for "self" to include a social domain. This reaises questions about what happens to dieas within social processes, and it makes me think of Bateson's Steps to an Ecology of Mind. Also, the observation that "it might be called self-replicating in the memetic sense; if you drive your Chevy Impala around town and lots of people see it and like it and order their own from Chevy" makes it sound like you are really talking about a mimetic process, not a memetic one.
It strikes me that for you to rely on "memetic" rather than "mimetic," you do have to go on to say that "that Chevy Impala has in a certain sense used humans as a tool to make more copies of itself." Is this the crux of the matter? If it is, it seems to me that it is nice poetry but the worst kind of pseudo-science, perhaps an example of commodity fetishism
Of course, a host of people have argued that sociobiology and memetics involves a naturalization of bourgeoise ideology (Ashley Montagu, Marshal Sahlins, Richard Lewontin) -- I am not neutral and wouldn't try to contribute to an article on memes, but perhaps at some point someone can provide the defense against these charges. Certainly, the claim that the proposition (or if you prefer meme) that "cars use people to reproduce" is in some sense "scientifically," and not just poetically, meaningful requires a bit more explanation!
In addition, then, I have three suggestions, given your reflections, that I think will make this and other articles more useful to a general audience.
1) for this article, a clearer discussion of what is at stake in "self," and to what extent it relies on or subsumes social processes -- or possibly obscures and distorts them.
2) for the obviously closely related article on memes, you seem very well-suited to make some very needed revisions, including, I suggest, a discussion of how memetics is related to/different from mimetics and also Bateson's work on ideas.
3) and if you don't mind I would still appreciate an explanation of how memes are different from propositions (see my response to your earlier "ramble")
I appreciate your thoughtful willingness to engage my queries -- I still am not clear, but I also think your responses should not be limited to the talk page or this article; I really do hope you can use this as a basis to make some necessary revions of/expansion to the article on memes, SR
Well, I'll see what I can do. But keep in mind, I'm really not an expert in memetics; this whole discussion grew out of me simply adding a line merely mentioning them, since I had just finished doing the chain letters article and it occurred to me that memes should me mentioned as something that can support self-replication. I've never read Dawkins' books on the subject, or any significant papers on memetics, I've just picked up a general understanding through idle interest. This is one of the main reasons I haven't moved any of the more detailed stuff I've written here over into the main article, I have no idea what an expert would think of it. Bryan Derksen

Anyway, in the case of the Chevy Impala, I would consider it memetic replication because each of the people who bought an Impala after seeing the first one would become examples for yet more people. The spread of fashions and styles throughout a culture is one of the most commonly given examples of memetic replication I've come across. And as for the difference between memes and propositions, you're asking for more detail than I'm comfortable providing at this point. Put the question in Talk:Meme and see if someone more deeply into memetics can provide a satisfactory answer. Bryan Derksen

Memes do recieve scientific study, I can dig up some more references if you like (though I still think the chain letter evolution article is quite a good example all on its own. :). But even if it isn't, Wikipedia doesn't require a subject to be a "scientifically accepted theory" in order to be the subject of an article. Bryan Derksen

Prepare for extremely longwinded clarification on the nature of replicating systems and memes: Whoever mentioned the environment of the replicator was dead on. Let's look at some systems theory. We can define a system as something that exists within a domain (or environment), consists of parts that interact in various ways and has inputs and outputs. Think of a system in this sense, as a whole, greater(in effect) than the parts that it's composed of. Something that self replicates would be a type of system that causes copies of itself to come into being.
Self replicators are systems that interact with their environment to copy themselves. This is described as taking advantage of some form of reproductive machinery in the article, but all replicators do this to some extent, though it is harder to spot when it is less abstract. Bacteria as a system, takes in materials and utilizing those materials, it's internal structure and the properties of chemistry, creates copies of itself. Bacteria's replication is mostly internalized, but certainly a product of it's interactions with it's environment. Viruses utilize their environment in a more obvious manner, requiring specific systems(cells) to reproduce themselves. A little bit of abstraction takes us to computer viruses. The computer is the environment and it's a complex system (with easily identifiable points of input/output and internal structure.) A computer virus would be a structure of data that creates a replicating system when the computer processes it. It clearly exists within the domain of the computer, has to have the computer to reproduce, and it relies on the laws in which the computer processes data (structure of the processor) and other interesting environmental aspects like the operating system. There is usually a human element in computer virus's self propagation too, though unintentional: downloading and executing infected files. Most(all?) computer viruses have to have human interaction to spread, it's part of their environment and thus part of the structure of the (metaphorical? though still based on paterns of interacting matter, albeit abstractly) system of replication created by the interaction of data, processor and human.
Memes, therefore, would be patterns of thought within an individual that have properties that cause their reproduction in other humans. The environment of memes is the human mind and body, social networks and growing more abstractly, the physical wolrd(as it is with all replicators). Let's take an imaginary meme: drinking coke causes cancer, as shown by some scientific study. Ignore whether or not it's true. You hear this from a friend, and (s)he goes into enough detail about the study, that you decide to believe him/her. This creates the notion within you that drinking coke may cause cancer. Possessing this belief can cause the system that is your body to behave differently because the system that controls it (the mind) has just integrated a new functioning element. You stop drinking coke so much. You see your friends drinking coke, and you say "that stuff causes cancer" because you care about their wellbeing, and you explain the scientific study. A notion is created in some of their heads and the process repeats.
The meme is differentiated from the proposition in that the structure of it causes it to interact with our minds in a manner that is likely to produce action on our behalf that results in the replication of the meme. It's an abstraction of the same behavior as earlier: computer viruses are data structures that cause a machine to replicate themselves because of the design of the machine, viruses are structures of molecules that cause themselves to be replicated through cells because of the laws of chemistry. Indeed, if you believe that thoughts are created by chemical reactions in the brain (which governs our behavior), you can trace memes right down to particular extremely, extremely complex patterns of chemical and physical interactions within and among humans.
Anyway, a car could create a system in which it causes itself to be replicated through aesthetic->cultural->economic->physical reactions, but it's so abstract and unreliable that it'd hardly fall under the domain of what we call self-replicating systems. That's what we in the business call a bad example.
Hope that clarifies some things. -J.S. Nelson

I'm also a little confused. To me, it seems there are two forms of self-replication described here. From my understanding, memes are self-replicating in a sense that the theoretical concept of an idea has the effect on its environment that causes it to replicate. But comparing this to a self-replicating nanobot or a virus is a little different. A virus is an entity that itself takes the initiative to gather resources from its environment in order to replicate. A "nano bot", like a (biological) virus would use a toner to do the same. Memes, however, themselves don't take the initiative, but rather the initiative for replication is done by the environment of the meme. The environment would also decide if it will or will not replicate it. A virus looking for molecular resources looks to its environment, whereas the meme is looked at by its environment. Computer viruses, when looked at from a software level, act like biological viruses, looking for resources programatically, but on a hardware level, one could argue it is similar to a meme, in that it is a set of instructions which is given its initiative from its host, the computer. Are these two types important to the classification of some concepts under "self-replication," or is there another meme related concept I'm missing that attributes initiative to "ideas?" Personally I would prefer for the article to have, at the least, a description of how there can be physical self-replication, and theoretical, because right now there's not much of a distinction. I don't mean to sound petty, but I believe there are major differences between the two. NinjaSkitch (talk) 04:58, 27 November 2007 (UTC)

Contents

[edit] mention self-hosted compilers ?

Should this article mention self-hosted compilers ?

It is often the case that a compiler is a "self-hosted" compiler. (Other compilers, in particular "cross-compilers", are not).

Writing (the source code for) a quine can be seen as a small introduction to writing (the source code for) a self-hosted compiler.

A Assembler (nanotechnology) is much more similar to a self-hosted compiler than any of the other things listed, in the sense that

See http://c2.com/cgi/wiki?SelfReproducingProgram .

[edit] empty point is self-replicating?

Noticed this point in the article - the section that talks about an 'empty program being self-replicating'.

Seems to me to be a dubious statement. Nothing is 'done', so no replication can really be said to have taken place. Yes, it's a very clever idea, but I'm fairly certain that the idea of 'replication' requires some interaction between a thing and its environment; nothingness does not create nothingness - it simply continues being nothingness, and nothing happens.

Well, the "empty program" example is self-replicating IMO in that you need that initial empty file in order to get the compiler to create another empty file. The key requirement is that compiling it should result in another copy of itself, though, so I don't think scripting languages are an appropriate example. And the bit about a "region of empty space" being self-replicating is right out, since regions of empty space don't replicate at all. I'll rewrite the paragraph and see how it goes. Bryan 15:18, 9 Jun 2005 (UTC)

[edit] Atrribution for empty program

The article formerly said:

This elegant solution was apparently only first noticed by Jonathan Finn in 2002.

This is certainly not true. For example, see [1], which is a post from year 2000 referring to someone else having earlier observed the same thing. But the observation that an empty program is syntactically correct in many languages, and that it can stand as a trivial example of a self-reproducing program, is quite obvious, and so was probably noticed decades ago.

I have removed the reference to Jonathan Finn. -- Dominus

[edit] By which a thing may act?

The very first sentence of this entry leaves me confused. "Self-replication is the process by which a thing may act, and thereby make a copy of itself." There are a whole bunch of ways in which this could be read, but I don't think any of them are accurate. Gruber76 04:38, 13 April 2007 (UTC)

[edit] Hypothetical Self Replication concept

Hi, a hypothetical self replicating machine.. it works like this… There are several, similar 2D blocks freely moving about in 2D space… when i mean a block, it’s shape is similar to the movement of knight(horse) in the game of chess.. that is the block has the shape of the letter ‘L’….

A block when it collides with another block, interlocks with it to form a composite block, …

A Block if it collides with a composite block.. it interlocks with it to form a bigger composite block…. So in this way a composite block grows in size by attracting simple blocks to collide with it..

But at a certain condition the composite block may not have any free jutting points to interlock with the incoming simple block.. at this state it splits into two parts, so that the incoming simple block can interlock with either of the split pieces….

So here the overriding conditions are:

1. if two blocks (both either simple or composite) collide then they must either interlock or the composite block must split into two..

2. when two simple blocks collide they always interlock…

So here we have a simple block which interlocks with other simple blocks to form a composite block, and further grows in size by interlocking with more simple blocks.. and when it cannot interlock with anymore simple blocks.. it spilts into two parts.. and each of these two parts start to grow in size by interlocking until they cannot interlock anymore.. then they too split…and so on..

what say? Can i add it in the page as a hypothetical self replication example?

[edit] References for von Neumann

The best reference to obtain respecting the list of components defined by von Neumann is his lecture to the Hixon Symposium. It is within his paper that von Neumann first explicates his model, and hence the nature of components; i.e. the tape (genome) and the constructor (cell). William R. Buckley (talk) 15:54, 18 April 2008 (UTC)