Sunday, 15 February 2015

Evolution and inductive inference

Inductive inference refers to using knowledge to make predictions. It's the basis of the scientific method. This was once famously disputed by Karl Popper - but is now widely accepted.

Sequence prediction is a well-known type of induction problem. For example, what comes next: 3,4,7,11,? Inductive inference relies on knowledge acquisition - i.e. learning. Inductive inference is inherently fallible and probabilistic.

It is clear that evolution builds systems capable of performing inductive inference - namely animal brains. However, there's another link between evolution and induction - since both processes involve using knowledge of the past to make predictions about the future. This is perhaps not obvious, but if you think about it, every organism represents a kind of prediction about the environmental conditions it will encounter. The prediction is that the organism will encounter an environment have allows it to reproduce.

Many have linked evolution and inductive inference in this way. For example, in

Universal Darwinism
, John Campbell wrote:

The Darwinian process may be the only physical mechanism known to science capable of accumulating knowledge from experience. It performs inference and is a physical analogue of Bayesian updating.
Similarly, in Probably Approximately Correct, Leslie Valiant wrote:

To see evolution as a form of learning, we view the genome in evolution as corresponding to the hypothesis in learning.

Philosophers of science who view scientific knowledge acquisition as a form of Darwinian cultural evolution are also implicitly making the same link between Darwinian evolution and inductive inference.

So: what is the link between evolution and inductive inference? I have a couple of comments to make:

  1. The claim that Darwinian evolution is a type of learning (made by Leslie Valiant in Probably Approximately Correct), isn't really right. Darwinian evolution can also produce genetic drift - which has little to do with learning. Evolution sometimes results in knowledge acquisition and successful inferences. Other times it results in progressive knowledge loss and extinction. It depends.

  2. It is tempting to link fitness in evolution with scientific truth or accurate knowledge. However, this association is inferior in practically every way to linking fitness with popularity. Phlogiston and the aether are popular mistaken ideas. They are kept around to help show where not to tread. Death in evolution maps poorly on to falsification in science.

The idea that Darwinian evolution underlies most systems that perform inductive inference is important and under-appreciated. Those engaged in creating machines that perform inductive inference tend to associate Darwinism with genetic algorithms. Those are often seen as being just one tool in a large toolkit. They are generally used in those cases where the only thing you know about your solution space is a scalar quality metric. Knowledge of memetic algorithms paints a rather different picture. In fact, evolutionary algorithms are fundamental.

Monday, 9 February 2015

The evolutionary gene

The idea of an evolutionary gene dates back at least to G.C. Williams (1966) - who said:

In this book I use the term gene to mean 'that which segregates and recombines with appreciable frequency'


In evolutionary theory, a gene could be defined as any hereditary information for which there is a favorable or unfavorable selection bias equal to several or many times the rate of endogenous change
Williams clearly defined genes in information-theoretic terms, saying:

The gene is a package of information, not an object.


A gene is not a DNA molecule; it is the transcribable information coded by the molecule
I think that the idea of a gene as consisting of heritable information has stood the test of time. However, the idea that genes are defined in terms of their frequencies seems more suspect. Terms like "appreciable frequency" and "several or many times" lack scientific rigor. Presumably they were used in order to prevent entities which are too complex from having 'gene' status. However, there seems to be no compelling reason to build them into our conception of a gene. Similarly, invoking "selection bias" seems to define unfairly neutral genes out of existence. Again, this is unnecessary - and can be simply avoided.

Instead of Williams mutually-contradictory definitions, I have proposed defining a gene as:

a small section of heritable information
The definition makes no mention of DNA, nucleic acids - or of living systems. It is a fairly general term - and generality is usually a virtue in science.

Richard Dawkins was another early pioneer of informational genetics. Although he initially used the "gene" concept he eventually substituted "replicator" - suggesting that this concept was more clearly substrate neutral. However, the resulting replicator revolution has not gone very well - and many years later there's no science of replicators that can compete with genetics. I don't think we need two sciences of heredity. It seems better to improve the existing field of genetics than to attempt to create a new scientific field that competes directly with it.

It is worth noting that the common definition of evolution in terms of changes in gene frequencies depends critically on the use of the evolutionary gene. Without the evolutionary gene, the idea that evolution consists of changes in gene frequencies would exclude cultural and environmental inheritance - and would make no sense.

In modern times it has become fashionable to claim that evolution is too "gene-centric" - and pays too little attention to other forms of inheritance. For example, here is Robert Kadar:

We now know genes are sufficient but not necessary for natural selection because 1) genes are the likely product of selection and 2) genes are only one source of heredity among others. The gene-centric view of evolution is crumbling!
Such sentiments make no sense in the context of the evolutionary gene. Genes are the units of inheritance in evolution. All inheritance is mediated by genes - just as all messages can be represented by bits. Defining the term "gene" so that it is stupid and useless is not good scientific practice.

Another group of biologists study what they call "epigenetic inheritance". Again, this whole concept makes no sense in the light of the evolutionary gene. Inheritance is genetic - by definition. The term "epigenetic inheritance" is an oxymoron.


Memetic sterilization

Culture has helped humans conquer the planet - and there are currently over seven billion humans in existence. The average effect of memes on their hosts has generally been pretty positive.

However, memes often have a remarkably negative effect on reproductive output. In what is widely known as the "demographic transition" women in more developed countries have fewer babies. Roughly, the richer the country is, the fewer babies are made. The culmination of this effect is seen in Japan - probably the most meme-rich country in the world. There, we see sub-replacement fertility and population decline.

One possible explanation for this involves r/K selection and the idea of a superstimulus. Standard r/K selection theory suggests that organisms may be adapted to respond to increased wealth with greater investments in offspring quality relative to offspring quality - more 'K' and less 'r'. It is clear that r/K selection theory explains some of the reduction in offspring number that is produced by wealth. However, the sub-replacement fertility seen in the real world is pretty clearly maladaptive. A possible explanation is that unusually high levels of wealth could result in a superstimulus and lead to the adaptive mechanism described above operating outside its normal range and malfunctioning.

There are also theories based on memetics. The idea that memes are involved is corroborated by the strong negative correlation between the number of years of education young women receive and the number of children they have. Few things stop your eggs from being fertilized as effectively as a college degree.

In theory, memes can benefit by diverting host resources away from reproduction of the host germ line and into the production of memes. The classic example of this is priests. In some denominations, priests have no children. Instead they devote their lives to spewing out a long string of memes: spreading the word. Richard Dawkins famously covered this hypothesis in The Selfish Gene, writing:

The meme for celibacy is transmitted by priests to young boys who have not yet decided what they want to do with their lives. The medium of transmission is human influence of various kinds, the spoken and written word, personal example and so on. Suppose, for the sake of argument, it happened to be the case that marriage weakened the power of a priest to influence his flock, say because it occupied a large proportion of his time and attention. This has, indeed, been advanced as an official reason for the enforcement of celibacy among priests. If this were the case, it could follow that the meme for celibacy could have greater survival value than the meme for marriage. Of course, exactly the opposite would be true for a gene for celibacy. If a priest is a survival machine for memes, celibacy is a useful attribute to build into him. Celibacy is just a minor partner in a large complex of mutually-assisting religious memes.

Specific technologies for sterilizing humans have evolved. Barrier contraceptives prevent sperm from reaching their targets. Chemical contraceptives mess up the female reproductive system, preventing conception. Abortion has become quick and easy - and there's even a "morning after pill". Evolution linked the human reproductive drive fairly strongly to the sex drive. Contraceptives break this link. Men can have sex without investing any resources in parental care. Women can have sex without going through labour and childbirth. Many men and women apparently choose to do this.

Memes whose transmission is vertical with respect to the generations of their hosts can be expected to have interests that are aligned with those of their hosts. Arguably we see such a transmission pattern with some traditional religious systems - with the Amish springing to mind as an example. However in the modern world, advances in communications technologies have led to meme transmission patterns that tend to be horizontal with respect to host generations. In such cases, we can expect to see more parasitic memes thriving - unless increased efforts are put into preventing their spread. However, in the case of contraception, the memes involved seem to be largely unopposed. It is true that some religious factions object to abortion while others discourage use of contraceptives, however overall, the fertility-reducing memes associated with "family planning" face relatively little opposition.

As an example of a sterilization meme, consider the essay Why it is important not to have children from Richard Stallman's personal site. Stallman is clearly a memetic hijacking victim. In his essay he clearly describes the competition between memes and genes and explains why he chose to propagate his memes - rather than his genes.

Memes are sterilizing humans on a massive scale. They also appear to be getting better at it. This leads to the obvious question of what the future holds. Will we see human fertility decline to the point where we see "peak human"?

I think that is the most obvious conclusion - although the supporting reasoning has relatively little to do with existing fertility trends. Instead it seems clear that the future dominant organisms will be engineered. They will, in short, be superintelligent machines. Humans might persist in such a world, but probably only as a very small piece of it. Perhaps their main role will eventually be in populating historical simulations. The machines will trace their ancestry back through us. We will be regarded as their progenitors. Human DNA will probably survive for a long time to come. However it is challenging to imagine a realistic distant future with very many "meat bag" humans in it. The current situation is just a stage the biosphere is going through before the rise of the superintelligent machines.

Sunday, 8 February 2015

Parasitic hijacking

In evolutionary theory, hijacking is an extreme form of manipulation in which one agent winds up performing actions that mostly benefit some other agent.

In order to perform a successful manipulation, the manipulating agent often has to be a close symbiont - in other words, a parasite.

To successfully manipulate its host, the nervous system is an attractive target. mind parasites. It is still possible to manipulate the host without invading their nervous system - and many parasites succeed by other techniques. They might synthesize hormones or neurotransmitters - or maybe make their hosts cough, sneeze or itch. However, these approaches don't really qualify as hijacking. One of the defining characteristic of a hijacking is that the hijacker directs many of the hijackee's actions.

The hijacking metaphor makes the most sense in the context of Richard Dawkins' characterization of the host's phenotype as being a vehicle. A parasitic hijacker may then hijack the host's vehicle and use it to its own ends.

Sometimes the victim's higher mental faculties are compromised during the hijacking - in which case the victim is often referred to as being a "zombie".

Hijacking parasites may be either organic or cultural. Memetic hijacking is a well-known phenomenon. Memetic hijacking illustrates the precise targeting that's available to cultural software. The host's motivational system can be reprogrammed to the point where they want nothing more that the success of the memeplex they are infected with. In some cases, the hosts are even sterilized by their memes - ensuring that resources that might otherwise be invested in childcare are directed into meme propagation.

Thursday, 5 February 2015

David Sloane Wilson on cultural kin selection

David Sloane Wilson has weighed in on cultural kin selection. It seems as though he's saying that he doesn't understand how it works - and is hoping others will explain it to him. The good news is that I've already published dozens of articles on the topic that explain it from a wide range of angles.

David's article suggests that his problem is that cooperative cultural interactions take place between organisms which "lack genetic relatedness, genealogical or otherwise". This seems like a basic point that is very easy to explain. Much cultural cooperation is based on shared memes. When two individuals have the same money, the same language or the same religion, they are more likely to cooperate. The more shared memes they have, the more likely they are to cooperate (on average). The idea of cultural kin selection is based on cultural evolution, kin selection acting on memes (rather than DNA genes) and symbiology and manipulation.

David says large spatial and temporal scales are part of the problem. I don't understand this problem. Consider the US dollar for example. This exists in billions of identical copies - and produces a lot of cooperation - which is all well explained by cultural kin selection - since the dollar bills are close relatives with r~=1 - and they clearly influence manipulate their hosts. The dollar's reach is global and it has lasted for quite a long time. It is not clear what the supposed problem with large spatial and temporal scales is.

To reiterate some by-now tired points, kin selection emphasizes close relatedness - where the process actually produces adaptations - such as the human breast. Group selection de-emphasizes relatedness. As a result advocates apply it to groups consisting largely of non-relatives - such as entire tribes - where theory predicts that the process is largely ineffective. As a result group selection has a long (and ongoing) association with junk science.

Mixing cultural evolution and group selection is a recipe for confusion. That's the very last thing the important science of cultural evolution needs. Mixing the two is not helping to educate the public, it seems more like a controversy-based marketing strategy. To me it looks like self-promotion at the expense of misinformation.

To reiterate, it is not the case that group selection explains cultural dynamics that kin selection does not. Group selection enthusiasts have spent decades looking for such cases. They have failed - and now most of them have given up. I thought David Sloane Wilson was among those who had publicly thrown in the towel - and given up this quest. This article suggests that the old group selection dream of finding new science and making original predictions still lives on. That does not seem like a good thing.

Monday, 2 February 2015

Phenotype terminology

"Phenotype" is one of the more fought-over concepts in evolutionary theory.

Richard Dawkins proposed calling the phenotype a "vehicle". David Hull proposed using the term "interactor". Gouyon, Henry and Arnould proposed the term "gene avatars".

The Dawkins "vehicle" conception has a curious history. Dawkins at first promoted it. When faced with Hull's near synonym "interactor" he said (1982):

Much the same point has been realized by Hull. (1981), but I prefer to persist in expressing it in my way rather than to adopt his terminology of "interactors" and "evolvors".

Later in "Burying the Vehicle" Dawkins wrote:

I coined the vehicle not to praise it but to bury it. This is, paradoxically, why vehicle is a better name than Hull’s interactor. Interactor comes too close to the (messy) truth and therefore doesn’t merit a helpfully decisive burial.

Dawkins subsequently went on to use the concept as though it had not been "buried" at all, for example here:

The key is to abandon the word 'fitness', replacing it with the concepts of replicators, vehicles and the extended phenotype.

These contradictory approaches to the "vehicle" term have become part of the terminology's baggage.

I find "interactor" a bit of a mouthful, while "vehicle" seems somewhat more acceptable. Hull's various criticism of the term "vehicle" seem bogus to me. For example, Hull claims that the term "vehicle" makes the organism seem too passive - like a giant robot controlled by its genes. I think Hull must have not used public transport very much. I also classify Hull's claimed distinctions between "interactor" and "vehicle" as being "mostly fluff".

Both "interactor" and "vehicle" are historically tied in a bit with the "replicator" concept - which has received its share of criticism. In particular, the etymology of "replica" strongly suggests high-fidelity copying - while in most of evolutionary theory, copying fidelity is a parameter, which can take a wide range of values. For some, this appears to have tainted "interactor" and "vehicle" by association.

"Phenotype" seems to have remained the most popular term. It has useful cousins: phene, and phenome. The terminology does have some disadvantages, though: The term "phenome" has a very muddled definition - which (confusingly) fails to mirror the definition of "genome". The terms "phenotype" and "genotype" are (confusingly) used to play multiple roles - referring to both all the traits in an organism and to a particular trait.

Like the term "evolution", the term "phenotype" doesn't come in "meme" and "gene" varieties. Just as it would be nice to have access to the terms "memevolution" and "genevolution", it would be nice to have "meme" and "gene" variants of the term "phenotype". Memeticists have proposed "phemotype" has been proposed as a term applicable to cultural evolution - but this term seems to me to be too irregular to endorse.

The Genotype-phenotype distinction neatly foreshadows the rise of information theoretic accounts of evolutionary processes. The idea is a lot like the hardware/software distinction in computer science.

For some reason, the Genotype-phenotype distinction has caused much controversy in cultural evolution. It all seems tied in to the confusion surrounding cultural genes: memes. I'm not really sure why this confusion exists - these all seem like basic, foundational concepts to me.