2.4. Adaptability of systems

The long-term persistence of a system also requires that the system is adaptable to changing circumstances. 

As complex systems are very difficult to understand, it is not surprising that adapting them to unknown changes can be overwhelmingly difficult. Even if we had the ability to change systems in any way we wanted (although no actor in complex systems has this ability), we simply do not know enough about how systems work or about future events to be able to adapt them in a meaningful way.

How then do systems adapt to changing conditions, if not through rational design? Answer: through trial and error.

Biological evolution

The millions of different species on Earth, with their own characteristics and traits, have evolved without rational design through the mechanism of natural selection. When there is genetic variation between individuals, natural selection favours those traits and characteristics that contribute to the survival and reproduction of the individual. This simple mechanism underlies all biological diversity.

Interestingly, biological evolution has also favoured mechanisms that produce variation. In sexual reproduction, the genetic information of the parents is mixed so that the offspring are different from their parents and also different from each other. However, sexual reproduction is difficult and expensive compared to clonal reproduction, i.e. the production of genetic copies. Unlike sexual reproduction, clonal reproduction does not require a search for a mate. Clonal reproduction also does not require males, which is why clonal reproduction is twice as efficient as sexual reproduction. So why is sexual reproduction still very common?

Numerous studies have shown that sexual reproduction is necessary for the long-term survival of a species (hundreds or thousands of generations). Clonally reproducing species may thrive for a few dozen generations, but in the longer term they become extinct because they are unable to adapt to a changing environment. For example, clonal species are easy prey for parasites that evolve to exploit a population of genetically similar individuals.

The overwhelming majority of all modern species can only reproduce sexually. In vertebrates, for example, clonal reproduction is only occasionally found in a few species of fish and lizards. All mammals reproduce only sexually. Thus, over the long term, the successful species have been those for which efficient and straightforward clonal reproduction is simply impossible.

Indeed, it seems that the inability to reproduce clonally has been the reason for the success of modern species. A rapidly reproducing clonal 'mutant', because of its efficiency, can indeed displace its sexual conspecific partners within a few dozen generations, only to become extinct itself a little later, when lack of variation prevents adaptation to a changing environment. Only species that are simply incapable of clonal reproduction are safe from this fate.

Cultural evolution

Cultural evolution refers to the change in behaviour, especially human behaviour, that is based on knowledge, skills and technology passed on from one generation to the next. Cultural evolution has enabled humans to survive in many demanding environments, and technological progress, which is part of cultural evolution, has made possible such things as space travel, information technology and modern medicine. The pace of technological development has been dizzyingly rapid over the last few hundred years and continues to accelerate.

Cultural evolution is much faster than biological evolution. One reason for the speed of cultural evolution is the way in which new ideas and new ways of doing things emerge. In biological evolution, new traits arise from random mutations. Only a very small proportion of new mutations are beneficial; the vast majority are harmful. In cultural evolution, on the other hand, new ideas and practices can be based on reasoning: the variation produced is therefore at least thought to be mostly beneficial. This directed variation is the first reason for the speed of cultural evolution.

The second reason for the speed of cultural evolution is that new skills can be learned and combined almost without limit. In biological evolution, beneficial mutations arise very rarely and it also takes dozens of generations before they become common in a population. Also, in biological evolution, it is almost impossible for mutations that are individually harmful but beneficial when combined to become widespread. Biological evolution therefore proceeds slowly and in very small steps. Cultural evolution is not limited in the same way to the gradual improvement of already existing things, but completely new solutions are also possible.

The more there are new ideas, the more widely they spread and the more they are combined, the faster the cultural evolution. Urbanisation - the growth and densification of human communities - is a key driver of cultural evolution. The development of technologies for storing and transmitting information, such as literacy, print media and information networks, have also played an important role. In the 21st century, the development of information networks in particular has largely removed the temporal and spatial constraints on the movement of information. Recently, however, many authoritarian states, such as China and Russia, have started to severely restrict the movement of information both within and across their borders. 

Here we again return to the modularity of the system: rapid cultural evolution is favoured by networks with many members and within which information flows easily. Unlike in biological evolution, where a mutation in one species cannot, as a rule, be transferred to another species, in cultural evolution new ideas can be easily transferred from one network to another. In a globally networked world, ideas and practices moved effortlessly across cultural and sectoral boundaries of all kinds (although in some parts of the world, the current trend seems to be towards diminishing links with the rest of the world).

Principles of adaptive systems

Complex, long-lived systems are adaptive and self-organising. Biological evolution and cultural evolution provide an excellent illustration of the characteristics that an adaptive system must have.

First, there must be modularity at lower levels of the system hierarchy, and variation among these modules. In biology, this might mean, for example, variation between individuals, in a market economy, competing firms, and in public administration, cities that can organise themselves. Modularity allows different solutions to be tried out without jeopardising the whole system if a new solution does not work.

Secondly, the components of the system must be interconnected to the extent that solutions that work can be adopted by the system as a whole. In biological evolution, this happens slowly as natural selection favours beneficial mutations. In cultural evolution, this can happen very quickly; social media, for example, spread memes almost instantaneously around the world (without taking a position on the usefulness of the memes themselves).

The third point to consider is that control of the system must be relinquished so that it can create its own workable solutions. Somewhat paradoxically, preserving the system in the long term means allowing the system to change, and to do so without knowing the end result. 

Change, however, is usually greatest and fastest at lower levels of the system hierarchy, while at higher levels of the hierarchy change tends to be slow. For example, ecosystem structure may remain relatively unchanged even if changes in species occur, and the societal system may remain for most part unchanged even if economic actors and economic structures change.

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