I've long recognised the possibility that infections could attack the host immune system to create a hole to penetrate host defenses - and that such a hole could then let in other parasites. Clearly these dynamics apply in cultural evolution as well - as is seen in cultural immune deficiency disorders.
This article is about a related set of strategies involving diverting host immune system resources elsewhere. Rather than directly attacking the immune system parasites may be able to create a diversion. One strategy would be to absorb host immune resources via deliberate immune stimulation using expendible, fake targets. Another strategy might be to liberate suppressed persistent infections already present within the host by making holes in the immune system for them.
The former strategy has some well-studied examples. Some parasites release what are known as superantigens - which act to stimulate the immune system, sapping its resources.
A couple of analogies illustrate the proposed effects. Invaders sometimes liberate prisoners from the territories they are invading. The reason is not always clear - but they may be creating a diversion which saps the resources of the defenders. They may also engage in arson. Causing chaos can help them to achieve their own goals. Another analogy involves the saying that "the enemy of my enemy is my friend". It is widely recognised that uniting against a common enemy can result in strength gains. Orwell wrote about this in the book "1984". Unrelated parasites may effectively gang up on their hosts - since they have a shared interest in a weakened host immune system.
I don't have much in the way of concrete evidence or examples in the cultural domain to offer in this post. However the possibility that these dynamics might also apply to cultural evolution seems intriguing.
In the symbiont hypothesis of eusociality, symbionts manipulate their
hosts into coming into close contact in toder to facilitate their own
reproduction - which often depends on hosts coming into contact with
one another. In turn, hosts coming into close contact with one another
creates opportunities for other symbionts to spread between hosts.
This creates a positive feedback loop - where more and more symbionts
of different types join with their hosts, creating an ecological
web of interactions which pulls the whole system into a deeper and
deeper symbiosis - resulting in eusociality. This idea is intended
to complement - rather than compete with - more conventional explanations
of eusociality which invoke kin selection. Kin selection is obviously
important, but the symbiont hypothesis likely also has a role to play.
Of course, some of the symbionts will be parasites. While also playing
a role in pulling their hosts together, too many parasites are bad,
and eusocial creatures often go to considerable lengths to eliminate
them - with antibiotic compounds, grooming rituals, hairlessness,
and highly-active immune systems. It seems likely that opposing
selection pressures from parasites
will form part of the "overcrowding" forces that eventually
halt the progress towards greater levels of sociality.
Humans can hardly be classifed as being eusocial yet. As Matt Ridley
sometimes jests, even the English don't let the Queen do all their
reproducing for them. However humans are ultrasocial and seem to be
headed towards full-blown eusociality with functional "individuals"
forming at higher levels than human individuals - such as companies
and organizations. We also have
cultural eusociality. We may not be
genetically eusocual but parts of our cultural heritage is memetically
eusocial. Indeed some of it consists of multiple identical clones
produced in factories (for example, think dollar bills or mobile phones).
Because they live in close quarters with one another ultrasocial creatures
are vulnerable to parasite transmission. As a result they often have
highly active immune systems to compensate. Humans exhibit one prominent
trait associate with parasite defense - they are hairless. Over time, our hairlessness
has been the topic of much speculation, but it seems fairly clear that a
significant part of the story is that being hairless allows us to pick
parasites off ourselves and each other, and denies the parasites shelter.
Of course, parasites can still shelter in clothes and bedding - but those
can be discarded.
My purpose in this post is to draw attention to the corresponding memetic
phenomenon. Memes are drawing us together to promote their own
reproductive ends - and as we grow closer, memetic
parasites are likely to become a bigger problem - as the most virulent strains
of memes from all over the planet reach the most vulnerable humans in
each society. As a resut, fertility has already plummeted in places like
Japan and South Korea. It seems likely that humans will respond with
heightened immune responses - both genetic and memetic. Memetic defenses
include education, skepticism and memetic vaccines targeted against
specific problems, such as pyramid schemes. Memetic probiotics can
be used to fight bad memes with good memes. We have hospitals to help
fight organic diseases, and there will probably be an upswing of
simiar rehab facilities designed to treat cultural infections. In the
past exorcisms heped to serve the function of casting out bad memes,
though these days we have more secular versions - such as weight watchers,
alcoholics anonymous, smoking rehab, drug rehab, gymnasiums and the samaritans.
Quarrantine is smetimes used to fight organic diseases - and there are similar cultural
ohenomena - including "gag" orders, DCMA take-down notices and imprisonment.
Bill Hamilton famously was one of the first evolutionary biologists to take parasites seriously - seeing their influence everywhere. Many have subsequently followed in his footsteps. One interesting paper on the topic which I recently took in is this one:
Gregory Cochran may be known to readers of this blog because he co-authored the book The 10,000 Year Explosion: How Civilization Accelerated Human Evolution. The paper here argues that pathogens have been consistently underestimated, and we ought to be considering them more frequently in cases where fitness is adversely affected.
The paper is all about organic pathogens. However the authors appear to be ignorant of cultural evolution, and don't extend their argument to cultural pathogens. Nor is there any discussion of meme-gene coevolution. Despite this, many of the arguments they give are equally applicable to cultural evolution.
One of the examples the paper gives is human male homosexuality. Although to date, no pathogen has been discovered that causes human male homosexuality, there's circumstantial evidence that suggests that pathogens may be involved. While thinking about cultural evolution it occurred to me that there's an example of cultural pathogens causing homosexual interactions between males: the well-known case of priests and altar boys.
It's long been argued that religious memes can sterilize priests to divert resources from genes to memes and thus promote their own propagation. Dawkins (1976) gives this argument as a hypothetical example. Homosexuality could be being promoted by memes for similar reasons. Though courtship and mating do use some resources, homosexual relationships do mostly manage to skip the cost of producing children - the resources saved could go into meme propagation.
Priests seem to go for young boys (rather than young girls) about 80-90% of the time. Indeed, the church apparently seems to be an attractive institution for homosexual men and many priests are gay. However the frequency of gay priests doesn't explain the frequency with which boys are targeted. Perhaps young girls are better guarded, or maybe they are more clearly prohibited for priests in scripture. Anyway the evidence is not conclusive, but memes do appear to be promoting male homosexual behavior in this case.
Knowledge of cultural evolution is invaluable in understanding the role of pathogens on human health. Consider the obesity epidemic, for example. That's an epidemic of Candida Albicans - and other fatness-promoting gut microbes. However it is also an epidemic of food processing technology and fast-food advertising memes. The food industrial complex develops ever-evolving tasty recipes and then uses memes as targeted vectors to deliver their their fat-promoting messages to consumers. The effects of memes and genes are tangled together in this case. Without an understanding of both you don't get the full picture.
The eusociality
symbiont hypothesis relating to the evolution of eusociality
pictures a positive feedback loop of interactions between hosts
and symbionts, with each new symbiont pulling the colony tighter
together as the symbionts manipulate their hosts into coming into
contact with each other in order to reproduce.
The positive feedback loop involved in the hypothesis is counteracted
by negative interactions involving hosts and symbionts - in other
words by parasitism. As hosts interact more closely parasites can also
spread horizontally between them. Since horizontal transmission promotes
misalignment between host genes and parasite genes, after a certain point,
parasites start to dominate more helpful symbionts - and then the hosts
start to behave as though they want to live further apart from one another.
The significance of parasites is evident in most social insect colonies.
These are vulnerable to parasitism - due to the close proximity of the
members - and it is not uncommon to see nests obliterated by parasites.
On the other hand, because of the parasite threat, the nests themselves
are often policed by cleaning squads. Disease eradication is a big theme.
Sick individuals are exiled and everything is kept remarkably clean.
Humans are a case study for the eusociality symbiont hypothesis. Our
symbionts are typically cultural, but the basic dynamics are much the
same - the cultural symbionts manipulate the humans into coming into
contact with each other in order to reproduce. The result is human
ultrasociality.
We know that humans living in close proximity are
more vulnerable to horizontal transmission of genes. We can see this
by comparing sick city dwellers with their more healthy country cousins.
Parasite transmission favors situations where humans are crowded together.
We have institutions to deal with this - such as hospitals.
Close proximity also favors horizontal memetic transfer. Assuming that
humans want to avoid exploitation by deleterious memetic parasites, we
are going to need organizations and institutions that promote epistemic
hygine. These will involve schools, as well as other types of training
more focused on the memetic immune system.
The negative effects of memetic parasites are clearly evident today.
We have an obesity epidemic driven by fast food advertising. There
are smoking, drinking and caffination epidemics which are widespread.
Over the counter drugs are widely abused. Paranoia epidemics are
fostered by the news media with resulting scares about terrorism,
global warming, vaccination, resource depletion, and so forth.
Epistemic hygiene can reasonably be expected to become a big focus.
Not necessarily the 'thought police' pictured by George Orwell - but
other government-level infrastructure to protect populations against
the negative effects of bad
memes.
One old and persistent fallacy relating to differences between organic and cultural evolution involves the claim that order of exposure to ideas matters - whereas that isn't true for DNA genes.
My foil in this case will be Felix Aurioles, who recently wrote:
It is because of this ambiguity that we must distinguish between behaviors or cultural traits, and the pieces of information that form them. There remains a likeness with genetics; when a phenotype is successful it propagates itself along with the information that encodes it. The difference lies, in that while a certain combination of genes always codes for a particular phenotype; the forms of cultural traits depend not only of the “memes” that compose them, but on the order they were absorbed and on the particular social circumstances they entered the culture.
My reply is as follows:
Gene expression is often context dependent - and it is often untrue that "certain combination of genes always codes for a particular phenotype". Instead, genes and environment interact during development to produce a phenotype. This happens in both organic evolution and cultural evolution.
It is also untrue that exposure order is not relevant to DNA-genes. For example, exposure to Hepatitis D followed by exposure to Hepatitis B has quite different outcomes to the reverse order of exposure. That is because Hepatitis D is a satellite of
Hepatitis B - i.e. it requires its presence to reproduce.
In organic evolution, a pathogen-caused immune deficiency disease (e.g. AIDS) might leave a hole in your immune system through which another pathogen (e.g. tuberculosis or pneumonia) might find easy entry. Similarly in cultural evolution a "faith is good" meme might compromise your memetic immune system - and leave you vulnerable to a "the end of the world is nigh" meme.
To effectively compare organic evolution and cultural evolution, you have to have some understanding of how both processes work. Only understanding one of them is not enough. Many critics of memetics from the social sciences often seem to think that whatever smattering of evolutionary biology and genetics they have picked up is enough to allow them to venture forth public criticisms based on their knowledge of these topics - and quite often they are mistaken.
Until recently I had considered the obesity epidemic to be primarily a cultural epidemic -
an epidemic of memes. Fast food companies spread their obesity-promoting memes throughout
the population using advertising (which consists of more memes) - and so manipulate people into eating more of their food, thus making the companies richer and financing the production of more obesity-promoting memes.
Obesity isn't just down to memes. Genes in foods are also involved - and humans
are breeding fatter, tastier and sweeter produce to better cater to the human palate.
However, it is becoming clear that another source of genes is also involved - genes inside
microbes in our intestinal flora. A variety of microbes have been fingered as obesity-promoting
strains. One famous one is Candida albicans.
This suggests the disturbing picture of obese individuals as folks whose bodies have been hijacked by
malevolvent microbes and turned into production factories that leave a trail of infection behind them.
The microbes eat their hosts' food for them and in return pump hunger-promoting substances into their bloodstream.
This more complex picture of a swarm of obesity-promoting memes and genes makes it
harder to blame the obesity epidemic on memes. However, it creates an interesting
and unusual situation - where humans are being manipulated both by a swarm of memes
and by a swarm of genes inside microorganisms. Can scientists learn anything from this
simultaneous attempt to manipulate the same trait by both memes and microbial genes?
It may provide an interesting opportunity to compare organic and cultural evolution.
For example, consider the question of whether genes or memes adapt faster. Most
previous attempts to study this question have compared memes with human genes.
However human genes reproduce at a very slow rate - and this is obviously
an unfair comparison and a walk-over for the memes. Comparing memes and gut bacteria
seems like a fairer comparison between the organic and the cultural.
Another related topic is cultural
opportunistic infections
when a host is infected by one parasite, that sometimes opens the door to other parasites.
A classic example is Hepatitis D - which only attacks those already infected with Hepatitis B.
In general, it is common for an overworked immune system to divert resources from one area to concentrate
on an existing attacking force - leaving some areas less well protected. Learened immune deficiency can result if invaders attack the immune system.
In the case of obesity, it is easy to imagine fast food memes promoting Candida infections. Probably hungry Candida sufferers are also more susceptible to fast food memes. Cross-domain opportunistic infections seem likely to be a real thing - but memeticists need to study this topic to better understand it.
There's a longstanding muddle associated with the "selfish gene" terminology of Richard Dawkins. The idea is that genetic selfishness tends to lead to anti-social individual behaviour. This misunderstanding has been transferred by some to memetics. Peter Richerson provides our example of this today:
One of the problems with the meme concept as it evolved is that users of the term focused far too heavily on the selfish potential of memes. But I think it is near to undeniable that cultural variants are sometimes selected to become selfish patthogens along the lines that Dawkins suggested.
Here, Richerson seems to be equating - or associating - selfishness with parasitism. To a memeticist, this is a false equation. Most memes behave selfishly. By that, what is meant that they behave as though they are self-interested agents that act so as to maximize their representation in future generations. Most genes also behave selfishly in this way. That is the meaning of the title of "The Selfish Gene".
Memeticists correctly focused on the selfish potential of memes. Memes are typically selfish - and treating them as such allows you to understand and explain their behaviour. However, selfish genes can reside in deleterious symbionts (like fleas), or mutualist symbionts (like gut bacteria). Selfish memes are the same: they can reside in helpful ideas (such as knots) or unhelpful ones (such as obestity-promoting memes).
Selfishness != parasitism. This is just a misunderstanding of the "selfishness" terminology - when applied to memes and genes.
Memes - especially deleterious memes - have been characterized by many as "viruses of the mind". However, they aren't the only brain viruses out there. They have to compete for that title with DNA-based exogenous viruses. These include Human herpesvirus-6 (HHV-6), cytomegalovirus, rabies, JC virus, HIV, Borna disease virus, LCMV, and probably many others.
Probably the most famous behaviour-control brain parasite in humans is Toxoplasmosis. It manipulates human behaviour working under the assumption the that human is a mouse. The Rabies virus is another brain parasite that infects humans and manipulates their behaviour, mostly under the assumption that they are lower animals.
However, there are probably many other behaviour-modifying parasites out there. A better understanding of these might help to improve public understanding of memetics. If people learn that their behaviour is being manipulated by DNA viruses, they may become more open to the proposal that their behaviour is also being manipulated by software viruses.
The idea of within-brain evolution of ideas highlights the aptness
of the virus/parasite/microbe comparisons often used in memetics.
In organic evolution, many microbes spend most of their time evolving within their hosts, only
occasionally bursting forth in an attempt to spread between them. Sometimes they lie
dormant for extended periods - in an attempt to evade the host's immune system.
Similarly, much memetic evolution actually takes place within the minds of human hosts.
Ideas sometimes grow, develop and fester within their hosts for months or years before
entering into a transmission phase.
Like many parasites, memes often face alternating selective environments. They need one set
of adaptations to survive within their hosts and another set of adaptations to spread
between them. The results are often a compromise.
Also, like many parasites inside their hosts, memes within minds are often surrounded by their kin -
often their close kin. For example, each time you hum a catch song, more very-similar memory traces
are laid down, reinforcing the memory of the tune. As with organic parasites, the kin-related dynamics
associated with within-brain evolution can be strong.
What to do if you have an over-active immune system - and are suffering from auto-immune self-strikes, in the form of allergies, lupus, multiple sclerosis, Crohn’s disease, etc.
One idea is to dose youself with parasites - and give your immune system some real work to do.
The challenge is to find parasites that will give your immune system a good work out without actually causing too many serious problems. Intestinal nematode worms seem to be a favourite parasite - and are used in helminthic therapy. However, the idea is a controversial one.
Reading about it, I quickly found myself wondering whether there a memetic equivalent. Scepticism, suspicion and conservatism act against bad memes. If we systematically wipe out the worst memes in the world, is there a risk that these defense systems will turn on the good memes, just so they get some exercise? What about the possibility of these defense mechanisms attacking the psychological infrastructure of their hosts?
These are interesting questions - but perhaps not pressing ones. We seem far from wiping out the worst memes in the world. Memetic parasites are widespread, and I don't think there's really a shortage of work for our memetic immune systems to do.
However, we do have people with hyperactive memetic immune systems - who have various learning difficulties as a result. Could "parasite therapy" help them?
Maybe. We do already teach people about bad ideas, to help them better appreciate good ones. We tell them about phlogiston, pyramid schemes and cults. However, this seems more like vaccination than "parasite therapy". In the organic realm, vaccination and "parasite therapy" are rather different - but perhaps in the cultural realm, they are more similar.
Anyway, "parasite therapy" for auto-immune disorders is an interesting idea. I'll bear it in mind.
Ted Cloak is a pioneer in the field. He published "Cultural Microevolution" in 1966, "Is a cultural ethology possible?" in 1968 and "Cultural Darwinism: Natural Selection of the Spoked Wood Wheel" in 1968.
His bio. says that he got a degree in cultural anthropology from the University of Wisconsin in 1966. He was among the researchers cited by Dawkins (1976). He has continued pursuing the evolution of culture over the decades since then.
This quote from the 1975 version of "Is a cultural ethology possible?" illustrates what probably inspired Dawkins:
In a human carrier, then, a cultural instruction is more analogous to a viral or bacterial gene than to a gene of the carrier's own genome. It is
like an active parasite that controls some behavior of its host. It may be in complete mutual symbiosis with the human host, in which case the behavior it
produces has survival value for itself through the value it has for the survival/reproduction of the host. On the other hand, it may be like the gene of a flu or
"cold" virus; when the virus makes the host behave, e.g., sneeze, that behavior results in extraorganismic self-replication of the virus gene but not in survival or
reproduction of the host or his conspecific. From the organism's point of view, the best that can always be said for cultural instructions, as for parasites of any
sort, is that they can't destroy their hosts more quickly than they can propagate. In short, "our" cultural instructions don't work for us organisms; we work for
them. At best, we are in symbiosis with them, as we are with our genes. At worst, we are their slaves
See Ted Cloak's home page for downloadable versions of many of his papers and further resources: http://www.tedcloak.com/
Memetics is deeply based on the science of symbiosis. However, sometimes the study of symbiosis seems to be in almost as much of a muddle as the evolution of culture.
I think one of the more obvious proposals for fixing its terminology involves the term "epidemiology".
Epidemiology is the study of health-events, health-characteristics or health-determinant patterns in a population.
Epidemic is worse - that says epidemics are concerned with disease spread.
At the moment, the word occupies a position which could potentially be useful to the science of symbiosis. What the science of symbiosis really needs is a term to refer to the spread of symbionts through a population of hosts.
However, epidemiology today seems to be all about health. Health varies due to host genes and inorganic environmental factors as well as being affected by symbionts.
At the moment, epidemiological terminology is used ubiquitously to describe symbiosis. However it is pretty bad at dealing with mutualisms. Students of symbiosis really need to decide on their terminology. The most obvious options are:
Hijack epidemiology and attempt to repurpose it;
Develop a "generalised epidemiology" variant that covers any trait - not just health;
Develop a "symbiotic epidemiology" variant;
Deploy some entirely new terminology to describe the spread of symbionts;
I think there's a good case to be made for the first option. The second option has some merits too. I expect that the fourth option is not going anywhere.
The "rationale" for the first option is: mutualist symbionts actually have a positive effect on health. Exactly neutral symbionts are too rare to be worth mentioning. As for the fact that health varies due to host genes and inorganic environmental factors: that is acceptable.
This is pretty-much how I treated epidemiology and its associated concepts in my "Memetics" book.
I think the etymology is supportive of widespread deployment in the context of symbiosis.
An alternative to repurposing epidemiology would be to develop a science of symbiology - with its own terminology. This would deal with the spread of symbionts - but not inorganic environmental factors such as chemical spills or nuclear fall-out. However, symbiology is currently underdeveloped and doesn't yet have good terminology in this area.
Perhaps in time, "epidemics" and "epidemiology" will lose their explicitly medical associations as well.
The terms "pandemic" and "plague" should also probably be taken away from medicine and repurposed for the greater scientific good.
One issue I which address in my book is why parasites tend to turn more benign when they approach saturation of their host population.
I still probably do not yet know the whole story - but I think I now understand some more parts of it:
In a mostly-saturated population, burning through the host's resources rapidly becomes a less effective strategy - since the rate at which new infections can be spawned goes down. So: keeping the host alive for as long as possible starts to look like a more realistic parasite strategy.
Parasites that saturate their host populations are subjected to different selection pressures. In particular - in the common case where the first parasites to arrive have an advantage over later arrivals - parasites become more "interested" in infecting hosts early in their lifecycle. That means infecting children - and the best people to infect children are their parents and family. That results in more vertical transmission down the host generations - so: in such cases, gene and meme interests would become more closely aligned.
Memes tend to promote human ultrasociality - and they create environments where their hosts are in close proximity and horizontal transmission is common - so host populations can become saturated fairly easily.
However, the first hypothesis is probably of low relevance to memetics: memes don't usually manage to execute those kinds of nasty strategy in the first place.
The second hypothesis may be more applicable to memes.
Hi! I'm Tim Tyler - and this is a video which responds to one of Steven Pinker's criticisms of memetics - the one where he compares memes to viruses.
In my book on memetics - which is out now - I take a look at some of the critics and criticisms of memetics. Steven Pinker is one of these critics. Pinker expressed a number of objections to memetics in a 2009 Harvard lecture. Here we will look at his claim that a viral interpretation of memetics can't be right - because words lack adaptations to evade the host immune system. Here's Steven:
[Steven Pinker]
OK, so to clear some basic things up first of all:
In memetics, memes are like genes. They are cultural genes. That is why the term "meme" is similar to the term "gene".
However, there are things which resemble viruses in memetics. Just as with organic viruses, a memetic virus is typically composed of a whole bunch of memes and some other components which make up its phenotype.
Cultural parasites are not an "yet another emendation of the analogy between cultural and biological evolution" but rather, simply a consequence of the relationship between those two things.
OK - now back to Steven's objections:
[Steven Pinker]
So: words are not much like parasites.
In this segment, Pinker seems to be some way off-base to me. The ideas he is criticising are some pretty strange ones - and are certainly nothing like my own views. Memetics allows for symbiotes that are mutualists, parasites or commensalists. There is no "parasites-only" version of memetics. Most individual words would be classified as memetic mutualists - rather than memetic parasites - since they benefit the host by helping them to communicate - and that explains why we have language.
However, if you look at word combinations, then there are both mutualist and parasitic entities are to be found - and then we can consider objections to do with parasites.
Here's one example of a mutualist sentence:
The square on the hypotenuse of a right-angled triangle is equal to the sum of the squares on the other two sides.
That's the Pythagorean theorem, and knowledge of it is probably usually benificial to its host.
An example of a more parasitic sentence is:
There's an invisible sky daddy who loves you, knows everything you do, and can save your immortal soul from damnation - so, the most important thing you can do in your life is to warn other people about how to avoid the eternal hellfire, by bringing them into his loving embrace.
This idea tends to screw up its host by diverting resouces which would otherwise be devoted to host reproduction to the reproduction of the parasitic piece of text.
However, note that this idea is a complex one. Pinker's objection that a mere word lacks the adaptive complexity required to overcome the host's immune system doesn't have much force here - because this parasite obviously has considerable adapted complexity - expecially if you consider the whole memeplex that would typically surround it in the wild. Also, the sections which aim to deactivate the host's memune system are really rather obvious: with references to love, rescue, embracing and appeals to family ties.
The reason deleterious memeplexes can evade the host memune system is essentially much the same for memes as for organic parasites.
It is not as easy as all that to defend against "sheer words". Words arrange themselves into a vast number of possible sentences, and encoding which ones are good and which ones are bad in the genome - and covering all the world's languages - would involve storing an enormous quantity of information there - and there just isn't enough space.
Also: verbally-transmitted ideas evolve quickly - whereas the host memune system is slower to respond and adapt - and it has to cope with a very large number of possible attackers, which represents a considerable burden on it.
Lastly, in the case of transmitted memes confronting a host memune system, there is a twist that does not apply to organic immune systems, which again hampers its ability to fully defend its host. Organic immune systems just reject anything alien. However, memes are - on average - beneficial - and letting the good ones through while rejecting the bad ones is a very difficult problem. If we knew in advance which ideas were the good ones, then we wouldn't need to rely on cultural transmission in the first place - we could just invent the good ideas. However, we don't know that - so we do the best we can using heuristics about who to copy from - and inevitably some bad memes get through the net. The price we pay for getting lots of good ideas culturally is that some bad ones make it past our defenses. However, that is better than beefing up our memune defenses - since that would stop lots of good ideas from reaching us too.
Some more videos associated with a story from my book: Cymothoa exigua - an isopod that eats and then replaces the tongue of a fish. Not that many cases where a parasite completely replaces a host organ are known - but this is one of them.
Could humans see any of their organs replaced by their symbiotes? Of course, this already happens if folk are disabled, they can have artificial limbs, and organs. In the long run, all our organs will probably be replaced. The brain could be one of the first to go. We have already heavily outsourced memory. If prediction capabilities become outsourced, the human brain may have a much reduced role to play. Also the human gut may become redundant early on. If food comes predigested, a complicated internal food processing system is no longer needed.
Oh, and I should probably warn you, the first video is not very nice: contains death.
In memetics, memes are the non-DNA genes of symbiotic visitors from the cultural realm. They influence our behavior for their own ends. Some of them are parasitic - in the technical sense that they typically reduce the fitness of their hosts. They
do this by manipulating the minds of their hosts, so the hosts spend more resources on spreading their memes. As a result there are often fewer resources available for spreading host DNA around. Some memes are sometimes characterized as "mind viruses" or "viruses of the mind". This is a similar idea. The analogy to organic parasitic mind control seems pretty obvious.
Mind control parasites are a popular phenomenon in science fiction movies. Here are some trailers for some of those movies:
In memetics, memes compose the genomes of symbiotic visitors from the cultural realm. They influence our behaviour for their own ends. Many of them are parasitic.
Humans are not the only type of creature to be infected with mind-control parasites. Here are some videos illustrating the phenomenon:
Ant liver fluke lavae - Dicrocoelium dendriticum.
Wasp and caterpillar. Parasitic Mind Control doesn't start until 3:30.
Cordyceps Fungus - attacking an ant.
Glyptapanteles (wasp) - using a young caterpillar host to guard its own eggs.
Leucochloridium Paradoxum is a parasitic flatworm that uses gastropods (snails and slugs) as an intermediate host. It turns their eye stalks into an animated display and makes them crawl out into the sunshine.
Toxoplasma Gondii - makes rodents like cats.
Spinochordodes Tellinii - Infects grasshoppers - makes them drown themselves.
Rabies - affects mammals - makes them "bitey".
Cuckoo - parasitizing reed warblers - behavioural manipulation by remote control using superstimulii.
Well, in our country," said Alice, still panting a little, "you'd generally get to somewhere else — if you run very fast for a long time, as we've been doing."
"A slow sort of country!" said the Queen. "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!"
The Red Queen Hypothesis refers to the way in which adaptation is constantly needed in order for the individuals of a species to maintain their fitness - in the face of constantly and rapidly evolving parasites. It invokes an evolutionary arms race between hosts and parasites. The short generation time of the parasites results in rapid evolution for them. This pushes the hosts around in gene-space, in order to avoid the attentions of the parasites.
The parasites are undesirable from the perspective of individual hosts - but they can have some overall positive effects. They constantly deform the fitness landscape of their hosts, keeping the hosts constantly off balance. This can result in previously separated peaks in the fitness landscape of the hosts sometimes turning into a ridge system - creating paths that lead away from what would otherwise have been sub-optimal adaptive peaks, and promoting evolutionary change.
Bill Hamilton promoted the idea that this Red Queen race helped hosts to invent sexual recombination - so they would be better able to defend themselves against the attention of parasites by maintaining a large quantity of genetic variation in their populations - thereby making life for parasites more challenging.
Sexual recombination is one of nature's masterpieces, and it seems likely that we have a Red Queen race to blame for it.
These days, a second Red Queen race is taking place. This time around, thee rapidly-reproducing symbionts are not bacteria and viruses, but memes - swarming in our heads and infesting our computer networks. As with the organic Red Queen race some of the symbionts are parasites which the hosts want to avoid. As before short generation time of memes and their rapid evolution pushes their hosts around in gene-space, keeping them constantly off balance, and accelerating genetic change in their gene pool.
The first Red Queen race may have led to the triumphant development of sexual recombination. What new techniques might the hosts use to defend themselves against exploitation in this second Red Queen race?
Will they use genetic engineering? A global hospital? Will meme therapy subdue the bad memes with good memes?
Or perhaps the memes will be triumphant. Meme warfare may mean that the most agressive memes are among those that rise to power. Parasites often evolve into relatively stable relationships with their hosts - but sometimes they wipe them out. That outcome becomes more likely when the parasites have multiple host species, and are not so dependant for their survival on the continuing welfare of any one of them.
At the moment, memes are pretty dependent on humans, but once our computer systems become sufficiently advanced, the memes seem likely to swarm out of the human heads and onto the new digital systems with considerable enthusiasm.
After they have estabished themselves fully in a digital medium, the memes may not need the humans quite so much. They will have multiple host species, and will not be so dependent on any one of them.
We will need to have a good and clear understanding of the dynamics of these types of coevolving systems to have the best chance of surviving our coming encounter with this type of situation.
For more details, about these kinds of possibility, please read my Memetics book - when it comes out in a few months time. It's going to look like this: [holds up book]
I have a previous article about cultural immune deficiency disorders. I've also written about cultural opportunistic infections - the cultural version of the well knnown phenomena, opportunistic infections.
In 
Bill Hamilton famously was one of the first evolutionary biologists to take parasites seriously - seeing their influence everywhere. Many have subsequently followed in his footsteps. One interesting paper on the topic which I recently took in is this one:
The 
One old and persistent fallacy relating to differences between organic and cultural evolution involves the claim that order of exposure to ideas matters - whereas that isn't true for DNA genes.
Until recently I had considered the obesity epidemic to be primarily a cultural epidemic -
an epidemic of memes. Fast food companies spread their obesity-promoting memes throughout
the population using advertising (which consists of more memes) - and so manipulate people into eating more of their food, thus making the companies richer and financing the production of more obesity-promoting memes.
There's a longstanding muddle associated with the "selfish gene" terminology of Richard Dawkins. The idea is that genetic selfishness tends to lead to anti-social individual behaviour. This misunderstanding has been transferred by some to memetics. Peter Richerson provides 
Memes - especially deleterious memes - have been characterized by many as "viruses of the mind". However, they aren't the only brain viruses out there. They have to compete for that title with DNA-based exogenous viruses. These include 
The idea of 
What to do if you have an over-active immune system - and are suffering from auto-immune self-strikes, in the form of allergies, lupus, multiple sclerosis, Crohn’s disease, etc.
Ted Cloak is a pioneer in the field. He published "Cultural Microevolution" in 1966, "Is a cultural ethology possible?" in 1968 and "Cultural Darwinism: Natural Selection of the Spoked Wood Wheel" in 1968.
Memetics is deeply based on the science of symbiosis. However, sometimes the study of symbiosis seems to be in almost as much of a muddle as the evolution of culture.
One issue I which address in my book is why parasites tend to turn more benign when they approach saturation of their host population.
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