Principia Memetica
Introduction
This paper discusses memetic replication and behavioural processes that are fundamental to evolutionary systems.
Contents
Replication
Mutation
Evolvability
Intermemetic Interactions
Altruism
Mutualism
Competition & Predation
Laws of Thermodynamics:
1. Transduction between states conserves energy.
2. The probability of transduction depends on the number of potentially stable states.
The stability of a given state is defined by the probability of transduction to and from other states.
Any state which increases the transduction of other states into replicas of itself is a replicator.
Replicators can be divided into various forms, although such divisions are not necessarily distinct:
The environment of a meme includes any state that influences memetic stability.
A meme is not an ontologically discrete unit, but can include complex systems, the constituents of which may not exhibit replicative properties when separated. The behaviour discussed in this section can therefore be applied to non-memetic evolutionary systems such as biological and artificial life. Interactions can develop between these systems, for example, memetic dependency on a biological/artificial host.
The division between a meme and its environment is defined by heritability and may not be distinct. As with all other memetic properties, heritability is ultimately environmentally determined.
Some environments may promote variation of a meme itself or errors in replication accuracy. In some memetic systems this is may prevent further replication. The rate at which such lethal mutations occur can be subtracted from the replicative reaction rate to give replicative success, or the growth rate of the meme population.
There is a probability that replicative properties will be retained by a meme following mutation.
Neutral mutations are those which have no effect on replicative success. The neutrality of a mutation can change with environmental variation.
When a non-lethal mutation occurs, a new meme population is created. Darwin (1859) states that in a system involving hereditary units, which can vary in terms of replicative success, evolution is inevitable.
However, a meme which can only undergo costly or neutral mutations will not evolve, it will simply be maintained by selection. Therefore the variation of replicative success must include potentially beneficial mutations for evolution to occur. This potential for beneficial mutation is often termed evolvability.
Evolvability
The adaptability of a meme can be defined as its capacity to survive environmental variation. This can be divided into short-term adaptability, involving behavioural responses, and long-term adaptability, or evolvability. As an evolutionary system ages, increasingly higher-level selection processes determine which replicator populations survive (Dawkins 1989). The rate of adaptation to such processes will depend upon the pressure exerted by long-term environmental variation.
The evolutionary rate, and hence adaptability to long-term environmental variation, is determined by mutational and replicative rates.
Evolution relies on mutation, yet mutation can reduce success. Therefore, a threshold exists for an optimum evolutionary rate, dependent on the cost of mutation and environmental variation. Repair mechanisms will evolve to reduce the most severe mutations and hence optimize this threshold.
A significant part of a meme’s environment will be replicas and, following mutation, other populations of memes. The interactions between different populations are dynamic and complex (Game theory). Stable interactions are known as an evolutionary stable strategy (ESS) and new memes have to overcome this stability to survive. The interactions between evolutionary systems can result in run-away selection pressures.
The influence of a meme on the success of its replicas is termed indirect fitness. Inclusive fitness represents a combination of direct and indirect fitness.
Altruistic memes will only spread if the direct cost is less than the indirect benefit. In biological systems this is known as Hamilton’s Rule (Hamilton 1964).
Altruism is any costly behaviour that benefits another meme. The pressure generated by replica interactions is kin selection. Parental care is a form of kin selection involving direct descendents.
The efficacy of altruism is dependent on its specificity towards kin as opposed to parasitic non-altruists. This leads to run-away selection of kin recognition and parasite evasion.
Therefore, the amount of altruism displayed between memes will depend on the probability of relatedness.
When the success of one meme is increased by that of another, pressure exists to optimize this interaction. A threshold will exist for how much one meme can gain from another without influencing it in some way. Further optimization requires either a negative or positive influence.
If one meme benefits from the by-product of another, then optimizing the success of the host population may indirectly benefit your own. A bi-directional positive effect will result in symbiosis up to a threshold level of interaction. The selection pressures for symbiosis are dependent on the strength of indirect positive interaction. Memes in a symbiotic relationship are often refered to as a meme complex, or memeplex.
The indirect flow of replicative success is heavily influence by the number of memes involved. The introduction of a third benefactor allows exploitation of mutual systems.
The reciprocity of mutualism is the temporal delay between the reception of benefits by those involved. Increasing reciprocity involves a greater risk and slower rate of benefit transfer.
Mutualistic relationships are not limited to intermemetic interations. Such relationships can develop with other types of replicator, such as genes.
If one meme reduces the success of another (bottom-up control), there is pressure for the inhibited meme to evade or retaliate. As with mutual effects, these indirect phenotypic interactions are heavily determined by the number of memes involved and their interaction strengths. Evasion becomes favourable over retaliation the more memes that are involved.
Reciprocal inhibition is unstable and such interactions will be selected against. However, if a meme gains from a reduction in host success, then this parasitic behaviour would be favoured. The dependency of a parasite on specific host success (top-down control) limits the amount of negative pressure it can exert. Infectivity of a parasite reduces this dependency and allows increasing virulence to develop.
Obligate parasitism occurs when the replicative properties of a meme become completely dependent on those of another. Extreme forms of obligate parasitism involve hijacking host replicative mechanisms. The pressure for host evasion/retaliation can be reduced if the parasite can offer benefits to its host.
Before the information age, memetic replication was completely dependent on biological hosts.
Mutation may result in competition within a meme itself. By definition, this creates in two new memes. If one is an obligate parasite of the other it is known as an outlaw. Survival of such outlaw memes depends on a threshold between its self-benefit and the cost to the host.
Predation - If parasite success is independent of host success, predation may occur. This involves complete loss of prey success. Such polar interactions favour run-away selection although it is biased for prey evasion. In genetic systems this bias is known as the Life/Dinner Principle (Dawkins & Krebs 1979).
The predation of two memes on a single prey meme is a form of indirect competition. Such memes are in the same trophic level. The level of competition between any two memes depends on the number and strength of phenotypic interactions they share. Unique combinations of such interactions are called a niche.
A prey meme will gain from being surrounded by other memes in a similar predatory niche. This is the memetic equivalent of a herd and is known as dilution. There will be a proximity threshold determined by resource competition.
It should be noted that competition can occur via communication pathways. This exerts pressure for determining the legitimacy of a signal. Modes of communication often evolve that cannot be deceptive due to physical laws (e.g. sound frequency to signal size).
Competitive relationships are not limited to intermemetic interations. Such relationships can develop with other types of replicator, such as genes.
Causes of learned behaviour:
Proximate - the biological/artificial mechanisms that interact with memetic information.
Ultimate - the selective pressures that have acted upon these mechanisms to preserve successful memes.
Early memetic adaptations, for example, the origins of human language, are of great significance to further evolution. The evolution of a certain trait will determine the constraints on further adaptation.
The commonality of a trait reflects the pressure for it to evolve and the lack of constraints for its evolution. Convergent evolution represents different mutational pathways resulting in the same trait.
The evolution of similar traits is less independent if it evolved from a common precursor. Therefore, the determination of fundamental evolutionary patterns (Kauffman 1985) from the commonality of independently evolved traits (Dawkins 2004) must take such precursors into account.
Geographical isolation provides natural experiments for recent evolutionary divergence. However, the nature of memetic systems that emerge from a given environment is extremely unpredictable. The fundamental behaviour discussed in the previous sections may not occur due to constraints.
The relationships between memes and their environments are extremely complex but relevant to aspects of biology, sociology, marketing and many other areas of study. Human behaviour is determined by a combination of memetic and genetic interactions with their respective environments.
A number of concepts require further investigation::
Animal Memes - The transfer of learned information between non-human animals.
Artificial Memes – The transfer of information between humans via books, videos, and computers, and the transfer of information between computers themselves.
Genetic Evolution - Genetic evolutionary theory should be able to make novel predictions of memetic evolution.
Reproduction - Memetic reproduction more closely resembles that of bacterial transduction. Memetic equivalents of anisogamy and sexual reproduction should be considered.
Other Genetic Equivalents - The similarities between genetic and memetic evolution need further investigation. Research into the memetic equivalents to the follwing would be of value: feedback mechanisms, trophic cascades, repair mechanisms, Muller’s Ratchet hypothesis, controlled variation & speciation.
Evolvability – The existence of long-term selection processes is fundamental to understanding modern evolutionary systems. This includes controlled variation and indirect altruism.
Control Mechanisms - The effect of a mutation is determined by environmental interactions. The similarities between chemical, neural and social communication and the command hierarchies they establish should be investigated.
Darwin, C. (1859). On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life . Murray, London.
Dawkins, R. (1976). The Selfish Gene. Oxford University Press, Oxford.
Dawkins, R. & Krebs, J. R. (1979). Arms races between and within species. Proc. Roy. Soc. Lond. B. 205, 489-511.
Dawkins, R. (1989). The evolution of evolvability. Artificial Life (ed. C. Langton). Santa Fe: Addison-Wesley. Pp. 201-20.
Hamilton, W. D. (1964). The genetical evolution of social behaviour (I and II). Journal of Theoreticl Biology, 7, 1-52.