The Evolutionary Theory of Cooperation and the Crisis of Democracy
Can human society learn from bacteria?
From the early days on, ideas (or their trivializations) of evolutionary theory have been used as arguments or intellectual edifices for social and economical reforms[1]. Particularly, neocapitalism seems to be based on the doctrine „survival of the fittest“: in short, the assumption is that a de-regulated system is self-optimizing due to competitive forces. It may be interesting to discuss if this idea is based on a correct understanding of evolutionary theory, and whether at all evolution is an appropriate framework to think about society, but this are not the topics of this short essay. Let us for now assume that evolutionary theory might give valuable food for thoughts about mechanisms that shape society, and in that about appropriate rules how to shape society.
It is interesting that, presumably as an answer to the global finance crisis, biologists increased their research targeting on heterogeneity in (isogenic) bacterial populations, the social life, division of labor, and in particular cooperation among bacteria. The general feeling is that we very well understand the evolutionary forces (selection) that result from competition, but we less understand the evolutionary basis and consequences of cooperation, though in nature, cooperation is as omnipresent as competition[2]. Cooperation is in the focus as this behavior can be considered as the archetype of beneficial social behavior. If we know how to stabilize cooperation, most likely we get some ideas about mechanisms that stabilize fairness and justice in society.
Bacteria, largely lacking the ability to recognize individuals and rational thinking, provide a simple, basic test system that allows to study cooperation, e.g. which conditions are required to allow or at least promote the existence of cooperative behavior in a population. This lately had resulted in the identification of a new, emerging field in microbiology, termed sociomicrobiology[3]. There is some hope that the results obtained here might have some more general impact, though one has, of course, to be very careful in the generalization of these results to human society.
Evolutionary theory and bacterial cooperation
In the present text, we focus on some approaches that seem to be of particular interest and potential relevance for the actual social problems.
Evolutionary stability
A central idea in the investigation of evolutionary dynamics is the term Evolutionary Stable State (ESS). A behavior/trait in a population that cannot be invaded by some rare mutant with another behavior/trait is called ESS[4]. We expect that, in the long run, a population approaches an ESS. The question we seek to answer is: Which mechanisms render cooperation as an ESS?[5] In another version, targeting on a slightly different question: Given a population of defectors (they do not contribute, but profit from cooperation) and only few cooperators — are the cooperators able to spread?
Tragedy of the commons[6]
What is the problem in bacterial cooperation? A typical situation where cooperation takes place is the production of a public good, e.g. an exoenzyme (an enzyme released from the cell into the environment that e.g. pre-processes nutrients). Assume a rare, cheating mutant, which does not produce the public good exoenzyme, appears in a world of cooperators. This mutant is not faced with cost for public good production but benefits from the public good production of the wild type. Thus, these mutants will grow faster than the wild type and eventually outcompete and replace the wild type. As a consequence, cooperation in a large, homogeneous population is generically not an ESS[7].
This argument does not allow to understand cooperation — obviously some additional factors are required.
Selfish gene and Haldanes argument
Richard Dawkins claimed in his seminal book “The selfish gene” (1976) that the entity under selection are genes; evolutionary mechanism favourize genes that spread in as many copies as possible. This idea does not imply that cooperation and cooperation do not exist, in contrary, in consequence (as Haldane already formulated earlier) a person should give up his/her own life to save two brothers or sisters (who share each 50% of his genes), or eight cousins (who share 12.5% of the genes). That is, cooperation becomes an ESS if individuals cooperate with close relatives, who share a high percentage of genes. This way out is possible if individuals recognize each other. In a world of bacteria, this argument does not lead further. However, we find cooperation among bacteria, there has to be something else.
Multilevel evolution and Cooperation
We do one step forward towards a more realistic model: a large population never is homogeneously mixing, but consists of (more of less separated) groups. That is, we have at least two levels of evolution[8]: groups and population. Each of the groups grow in size for a certain time, and then they are dissolved for a time into a large, structureless population. A small fraction out of this homogeneous, large population re-arrange into new groups and repeat the cycle.
This model captures the life-cycle of many bacteria rather well: bacteria often live in colonies, which dissolve if they become too large (such that, e.g., the nutrients become short). The bacteria go into a planktonic phase, and form new colonies.
Analyzing this model, we find two central observations: (a) the fraction of cooperators within each group becomes smaller in time (b) the groups with a large fraction of cooperators grow faster in population size than the groups with a small fraction of cooperators.
The combination of (a) and (b) can lead to the paradoxical situation, that the fraction of cooperators within the total population increases, while the fraction of cooperators within each group decreases[9] (Simpson’s Paradox). However, this mechanism reliably stabilizes cooperation beyond small stochastic effects.
The assumption for the groups to grow (exponentially) fast implies that the re-arrangement is connected with bottlenecks: the bounded carrying capacity of the ecosystem does not allow for unlimited growth. The mechanism to restrict the population size relies on the reduction of the population during re-arrangement.
This mechanism proposes that cooperation needs small, growing groups with periodic bottlenecks and re-arrangement to be an invasion-stable strategy.
Interpretations, conclusions and questions
We again emphasize that we need to be careful with the extrapolation of these results to society, though we think that these simple systems reveal some of the relevant driving forces that shape society.
The reasons for the crisis of democracy have been localized in as different fields as deliberate misinformation by commercialized press and social networks, neoliberalism in economic politics, big data and information (mis)use, or a de-solidarization in consequence of social reforms of the 90‘ths, to name but a few.
In view of the results sketched above, it could very well be the case that all these hypotheses, observations and analysis, which surely have importance at their own right, could be accompaniments and side effects of a more fundamental cycle. After the last large catastrophe, the second world war, increasing wealth provided positive conditions for the development of cooperation; cooperating groups (companies, neighborhoods, communities) would prosper rapidly, better than groups consisting of persons who act selfishly, and in this way form a role model for society. An overall agreement in society that cooperation results in better life conditions for everyone has perhaps been generally accepted. In a globalized society, sensible groups seem to be more difficult to define and sustain. Growth cannot last for ever, every ecosystem has bounded carrying capacities, a given technology opens up only a certain, limited amount of resources. For which reasons ever, economic growth was replaced by weak growth and stagnation. The simple mechanisms for cooperation discussed above require growth; stagnation promotes selfish behavior and cheating. If the number of cheaters becomes larger and larger, eventually this behavior will be more and more accepted by society. The overall social values change, cooperation, fairness and justice become less important, self-centering and eroding sociality is a consequence. It is worth a hypothesis that what we see in social media, in economic politics, and in the politics of isolation in several governments is a consequence of stagnation.
If so, we are faced with a serious problem. The longing of individuals for sensible, stable groups leads most likely in a direction that is not beneficial for society. Brute force localization — as a reaction to globalization — is no way out. Moreover, growth is not sustainable. Growth may be restored after a serious crisis (much more serious than the present crisis — so far), that leads to a breakdown of society and economics. This is no way out.
If so, we need strategies to ban cheaters in phases of stagnation.
If so, we need to restore cooperation as the role model for society.
If so, the simple evolutionary forces work against us.
We need to count on our rationality, and this idea may be — at least slightly — naive.
Of course, laws that force economics to serves society, and not vice versa, are required. We need laws that prevent the most serious self-serving behavior. However, it is of higher importance to restore a general agreement in society that outlaws selfish behavior, such that the amount of cheaters reduces automatically to numbers that are bearable by society.
Is a deeper understanding of the evolutionary stability of cooperation able to help in this process, or is this hope too innocent?
Information about the authors:
The late Burkhard Hense was senior scientist at the German research Center for Environmental Health in Munich. His main research interests were bacterial communications as quorum sensing, and ecology.
Johannes Müller is professor at the Center of Mathematics, TU München. His research fields are dynamical systems and stochastic processes with applications in life sciences.
Email: jomuemathe@gmail.com
[1] See, e.g., the work of Herbert Spencer, who (and not Darwin) formulated the principle of “survival of the fittest”.
[2] A.S. Griffin, S.A. West, A. Buckling, Nature 430(2004), 1024–1027.
[3] M.R. Parsek, E.P. Gerrnberg, Trend in Microb. 13(2005), 27–33.
[4] J. Maynard Smith and G. R. Price, Nature 246(1973), 15–18.
[5] M. Nowak, Evolutionary dynamics, Harvard Univ. Press, 2006.
[6] This term originates from economic literature, Hardin, Science 162(1968), 1243–8.
[7] Ch. Hauert et al., Sciences 296(2002), 1129–1132.
[8] S. Okasha, Evolution and the Level of Selection, Oxford Univ. Press, 2009.
[9] Ch. Hauert et al., Sciences 296(2002), 1129–1132.
