Sunday, 16 July 2017

Hitchhiking vs hijacking: vehicular metaphors for transmission vectors

In symbiology, "transmission vectors" are the name for symbionts that carry their partners around. So: mosquitos are "vectors" for malaria and deer ticks are "vectors" for lyme disease.

In memetics (and genetics), it is quite common to use "vehicular" metaphors when describing these. So, for example, we have:

The first two seem to cover many of the most significant cases. There's quite a bit of conceptual overlap between them. Until recently I have preferred to use the "memetic hitchhiking" terminology - largely because "genetic hitchhiking" is well-established terminology. However, in this post I want to reexamine the "memetic hijacking" terminology. I want to raise and address the question of whether these concepts compete, and whether they can coexist.

What is the difference between hijacking and hitchhiking? It is partly one of consent - a hitchhiker has permission to ride in the vehicle while the hijacker does not. Outcomes also differ - a hitchhiker rarely damages the vechicle or its owner, while a hijacker often does so. Another difference is control - hitchhikers rarely alter the destination, rarely control the vehicle and rarely eject the owner - while hijackers fairly often do these things.

With these differences in mind, it seems fairly clear that hijacking and hitchhiking are probably different enough concepts for memetic hitchhiking ...and... memetic hijacking to coexist.

At first glance, the idea of the rider having "permission" to ride in the vehicle seems irrelevant in the context of memes and genes. However, we can conveniently substitute whether the guest rider is beneficial or not - on the grounds that deleterious riders would not normally be granted permission to ride - if we "agentify" the memes or genes involved.

This gets us on to the topic of usage in genetics. There, "genetic hitchhiking", is standard terminology - and hardly anyone uses the term "genetic hijacking". However if the difference between hitchhiking and hijacking is the sign of the fitness difference the guest rider makes, then maybe geneticists should start doing so.

As you can see, I have warmed up to the "hijacking" terminology. That the contraction memejacking exists is another point in its favor in my opinion. It is true that it is a significant problem that there's no "genejacking" - but maybe there should be.

Saturday, 15 July 2017

Meme-gene-queme coevolution

We now at last have a significant academic literature on meme-gene coevolution. However few seem to have considered the dynamics of the meme-gene-queme coevolution that can be expected as a result of considering quantum Darwinism in the brain. This blog post is a brief attempt to share my thoughts on the topic.

The first thing to say is that it isn't just memes genes and quemes - Darwinian dymanics arise on multiple levels within the brain, for, for example, signals in the brain are copied whenever an axon divides, and are subect to selection and variation - producing a kind of neuronal spike Darwinism. Another type of Darwinian dynamics in the brain arises as a result of competition for resources between branching axon and dendrite tips. ideas are also copied with variation and selection within the brain - including ideas that don't normally qualify as memes because they were not the product of social learning.

One way in which we can expect the dynamics to differ from meme-gene coevolution is that culture is new on the scene, while the other kinds of psychological and neurological Darwinism have been going on for many millions of years. There will have been more time for the genes to adapt and reach a steady state equalibrium with these other Darwinian processes - while meme-gene coevolution is clearly out of balance and is still shifting.

An important way to understand the results of evolutionary processes is to consider their optimization targets. When there's coevolution there are usually multiple optimization targets, and one needs to understand how they interact by considering the power and speed of the optimization processes involved. Quantum Darwinism looks as though it could be fast, which means that we should take it seriously. Assuming that we reject Copenhagen-style versions of Quantum Darwinism in which branches of the wavefunction collapse and die, quantum Darwinism is a kind of splitting only, quasi-Darwinism - where differential reproductive succees in important while differential death is not. With this perspective in mind, the "goal" of quantum evolution appears to be to put us in the most split (and most splitting) worlds. One way to understand the implications of this is to take a thermodynamic perspective. World splitting is populatly associated with irreversible thermodynamic effects. What that means is that quantum Darwinism can be expected to behave like other kinds of Darwinism - in terms of maximizing entropy production.

I think this thermodynamic perspective helps get a handle on the significance of quantum Darwinism in the brain. If the brain ran hot, there would be lots of scope for quantum Darwinism in the brain, while if it runs cool, there's less scope for quantum Darwinism to operate. Most agree that the brain is on the cool side - considering what it is doing.

I think that genes are likely to be optimizing for cool brains, and brains that optimise for gene-coded functions. This may often pit them against quantum Darwinism in the brain. A cool brain is good news for quantum computation theories of mental function (fewer thermodynamic irreversible events means less chance of decoherence) - although those look implausible to me on other grounds. However a cool brain doesn't help the argument for quantum Darwinism being important in the brain.

Evolutionary processes liek to "harness" each other, to bend their optimization targets towards each other. Because quantum Darwinism in the brain has coevolved for millions of years with the genes, they have had a long time to find ways to harness the power of quantum Darwinism. However, the classical way for one evolutionary process to harness another one is by altering its fitness function. The genes might find it hard to affect the fitness function of quantum Darwinism since that is tied up with fundamental physics. That is going to make harnessing its effects more challenging. Another potential way for one evolutionary process to harness the effects of another one is by influencing the variants that it chooses between. However, this mechanism seems weaker and less useful.

My conclusions here are pretty tentative, but the picture I am seeing here is that the brain might not be able to make much use of quantum Darwinism because it is an alien selection process whose optimization target can't easily be controlled. In which case, the brain might be best off attempting to minimize its influence. This would be a rather boring conclusion. Mutualism and harnessing would be a much more interesting result. However, I stress again that it is somewhat uncertain. Maybe the brain can make some use of the power of quantum Darwinism by influencing the things it selects between. Or maybe evolution is smarter than I am and has found ways to make use of it that I haven't thought of.

Monday, 3 July 2017

Ecological success and dominance

Evolutionary biology's best-known measure of success is fitness. "Fitness" has become a popular term, and as a result of its success it has become overloaded with multiple meanings - e.g. see the 1982 Dawkins book chapter titled: "An agony in five fits". Most definitions share the property that fitness measures whether an entity - or a population of entities - is increasing in number. "Fitness" usually measures the extent of that increase in some way. From the perspective of ecology, fitness isn't the only success metric in town - it just happens to be one that can be easily applied to individuals. If broadening the perspective to include populations, one could also consider the population size, its expected probability of going extinct in some specified time, it rate of throwing off new distinct populations and some measure of how well it is capturing and using resources.

The last concept is the one that this post is about. I think of it as being "ecological success". Kudzu has it. Ants have it. Islam has it. The decimal system has it. I think one reason this type of metric is not more popular and better-known is that there's no consensus regarding the best way to measure it. A thermodynamic metric seems attractive to me: since resources can all (in principle) be manufactured from available energy. Another possible metric involves weighing the systems involved - to measure their mass. This is sometimes done when measuring the extent to which humans have conquered the globe, for example.

A sister concept is "ecological dominance". It refers to extreme levels of success - where competitors are either obliterated or marginalized.

These concepts can also be applied within particular niches. Entities which are doing badly overall may be succeeding in or dominating their particular niche.

If anything, attempting to apply these concepts to cultural evolution is even harder than with organic systems. Gene-meme coevolution results in entanglement in terms of gene and meme products, which makes weighing them and calculating the energy flux through them more challenging. The most common metrics used in cultural evolution are a bit different. "Mindshare" is a common concept which is used to measure cultural popularity within a cultural niche. Assuming that a meme is either possessed by a host, or not, and assuming whether they have it or not is measurable, the mindshare of a meme can be measured for a given population. Another common metric that is used is US dollars. Cultural products sometimes have monetary value, and sometimes that can be calculated or estimated. However, some of the most common memes are free. It seems as though these memes would be unfairly disadvantaged by value-based metrics of popularity. The internet has brought with it some other common popularity metrics: views, links, clicks and likes. Unfortunately the supporting data is not always publicly available. This data is beginning to be used by scientists.

Saturday, 1 July 2017

The symbiont hypothesis: an update

I've long been promoting the symbiont hypothesis as a theory relating to the origin of cooperation and eusociality. My previous articles on the topic include:

The theory fingers symbionts as important in the origin of cooperation, sociality and eusociality and there are obvious and far-reaching implications in cultural evolution, where memes promote social interactions between hosts in order to promote their own spread during those interactions. To quote from my 2011 article on the topic:

The idea is that meme reproduction depends on social contact between humans. Increased levels of social contact between their hosts are good for memes since this results in more reproductive opportunities for them. Memes that promote human ultrasociality have the effect of pushing humans into close proximity with each other, so the memes can infect new hosts.
I'm happy to report that there's been a recent increase in the number of scientists looking into the topic, and now there's a bit more experimental evidence bearing on the issue. Some of this work is summarized in the recent popular science article: Can Microbes Encourage Altruism?. The article mostly reports on computer simulations which demonstrate the effect - which is what I was looking for in one on my 2014 articles - but the latter part of the article covers empirical evidence from a variety of sources that microbes do, in fact encourage cooperation and social behavior in their hosts - and that this can be decreased via the use of antibiotics. The article cites recent work reporting:

fruit fly larvae are attracted to airborne chemicals released by the bacteria in their guts; the appealing scent may draw the larvae toward one another
...and...

When Bienenstock exposed mice to low-dose antibiotics in utero and soon after birth, the treated mice showed lower levels of sociability and higher levels of aggression than mice in a control group
These are still early days for the hypothesis, but the topic is clearly deserving of more research.


Update 2017-07-29: the article has now been syndicated in Scientific American.