Crossing the Complexity Barrier

Darwinism Evolving: Systems Dynamics and the Genealogy of Natural Selection

Depew, D. J., and Weber, B. H. ,

Cambridge, Mass.: The MIT Press. (1996).

The study of complexity and self-organization in living organisms offers a powerful, new way to understand the natural world.  It provides a profound and serious alternative to the reductionist program which has dominated biology since the early part of the 20th century.  But what does it imply for Darwin’s theory of natural selection, the bulwark of modern biological thought?  Over the past two decades, a number of researchers have shown how natural selection and complexity theory, far from being rivals, are in fact “marriage partners.”[1]

Of these studies, the one that I’ve found most rewarding is Darwinism Evolving by Depew & Weber, which gives an in-depth narrative of the thought currents around Darwin’s theory, from before Darwin all the way to the present day, using the narrative to establish and support their own approach.

They begin with an interesting take on Darwinian theory, describing how it developed in the context of both the political and scientific framework of the mid-19th century.  Politically, Depew and Weber show how Adam Smith’s view of the “invisible hand” could be powerfully translated from economics to biology.  In both cases, individuals struggle to do what’s best for them, and by doing so, blindly become agents in the natural laws of capitalism and evolution.  Similarly, the “gradualist” approach that Darwin favored in describing the process of natural selection, fit well with the prevailing political ethos of Victorian England.  They describe a chemist named W.R. Grove addressing a scientific meeting in 1866, telling his compatriots how: “Happily in this country practical experience has taught us to improve rather than remodel; we follow the law of nature and avoid cataclysms.”

Depew & Weber are not the first to note this political context (in fact they tell us how Karl Marx picked up on it as early as 1862.)  But they probably break some new ground in their linkage of Darwin’s ideas to developing theories in physics, arguing that:

… the Darwinian research tradition, while successfully resisting reduction to or incorporation within physics, has from the beginning used explanatory models taken from physics to articulate its core idea of natural selection.

They show how Newton’s laws formed a “generalized model for describing and explaining phenomena in fields beyond physics, even social systems” in the nineteenth century, and they offer a fascinating analysis of how the laws of statistical mechanics developed by Maxwell and Boltzmann had a profound effect on later, post-Darwinian evolutionary thinking.

This thesis really hits its stride when Depew & Weber follow the interactions between evolutionary thought and the second law of thermodynamics, which states that processes in a system will tend towards entropy.  They give an account of the strange life of Ronald Fisher, the first person to formally link evolution with the second law, with his view that “just as the world moves downhill by the exploitation of energetic gradients, so it moves uphill by the exploitation of fitness gradients.”  With a clear distaste for how evolutionary theories can be manipulated to support ethical idiosyncrasies, they note how “as his classmates went off to the slaughter of World War I, Fisher was writing in the Eugenical Review that although morality and aesthetics are both grounded in sexual selection, those who rightly rule in a society know that beauty is a higher value than morality.”

The linkage of evolution with the second law of thermodynamics becomes more rigorous and powerful as the story continues.  We’re introduced to Alfred Lotka’s thermodynamic theory of evolution which can be summarized as:

Evolution proceeds in such direction as to make the total energy flux through the system a maximum compatible with the constraints… In accord with this observation is the principle that, in the struggle for existence, the advantage must go to those organisms whose energy-capturing devices are most efficient in directing available energy into channels favorable to the preservation of the species.

Depew & Weber tell us how “with his vision of the unity of physics, chemistry, and biology, Lotka proposed this as a fourth law of thermodynamics.”

Perhaps the most important milestone in this narrative is the “seminal little book that appeared in 1944”, by quantum physicist Erwin Schrödinger called What is Life?, which threw “considerable sweetness, as well as light” on the subject.  Schrödinger’s breakthrough was to contrast an organic or open system with the universe as a whole, arguing that “the second law requires only that the universe as a whole must show an increase in entropy.  Eddies of order, or what Schrödinger called ‘negentropy’, could be sustained in the great flow of ever-increasing entropy.”

So life can be seen as a continual struggle against entropy, whereby cells, organisms or ecosystems take energy from the broader universe, organize it in ways that assist them (i.e. metabolism), and dissipate the waste back out.  This is why Ilya Prigogine, the next great thinker on this subject, refers to organisms as “dissipative structures.”

This narrative enables one to see current theories of complexity and self-organization within a full historical context.  Those who are “marrying” self-organization to evolution are, in fact, working on the fourth or fifth generation of matchmaking.  The difference now, as Weber and Depew point out, is that the new science of complexity has developed theoretical tools and data-driven applications that fundamentally change the project.  As they put it:

The first lesson to be learned from the new dynamics is that the world contains more novelty, diversity, and complexity than we had assumed…  Crossing the complexity barrier, accordingly, calls for … radical revisions in how scientific theories are to be analyzed and in how they explain when they are applied to problems… [I]t is not just physics and biology that must change to accommodate this fact but philosophies of science, too.

The implications of “crossing the complexity barrier” are far-reaching, and Depew & Weber explore some of these directions.  For example, a thermodynamically-based view of evolution leads to an understanding of evolution as occurring on multiple levels rather than solely on the individual organism (or as espoused in recent decades, the individual gene.)  It also supersedes the “competition” metaphor in traditional evolutionary narrative, as Depew and Weber explain:

Organisms will, on this account, be construed as informed patterns of thermodynamic flow.  Those populations will be fittest that best enhance the autocatalytic behavior of the reward loops in which they participate.  One advantage of this notion is that it makes it possible to contextualize natural selection to the wider array of processes in which it occurs, and to project a vision of ecological communities in which cooperation becomes as characteristic as competition, or indeed inseparably linked to it…

Not surprisingly, Depew & Weber come out strongly against reductionist thinking in general, and even more fiercely against Richard Dawkins’ particular style of that thinking, describing how he “invests his metaphors with disturbing semantic reverberations that harken back to Enlightenment themes”, giving the choice between being pawns of our genes” or “of a tyrannical Calvinist God.”  As I’ve described elsewhere, I’m in strong agreement with their view of Dawkins’ “false choice,” and the inherent limitations of thought offered by reductionism, which they describe as follows:

The problem has been that when everything is antecedently considered to be ‘nothing but’ atoms in the void, many real, important, and interesting phenomena tend to get explained away, brushed aside, eliminated, or, worse, crammed into the wrong explanatory box… Indeed… the reducing impulse undermines fairly huge tracts of experience.

The dynamical systems perspective is far from universally accepted, even by those who challenge conventional gene-centered evolutionary approaches.  Here is a critique from David Sloan Wilson, known for championing multi-level selection theory:

Embedded in the thermodynamics talk is the naive assumption that adaptation at level x … automatically leads to adaptation at level x + 1… It is… discouraging that ‘‘the emerging sciences of complexity’’ are so isolated from evolutionary biology that the mistakes of the 1940s and 1950s are being repeated.[2]

I disagree with Wilson about the “automatic” assumption.  I think the “complexity” part of modern systems thought leads to the understanding that there’s nothing “automatic” about the dynamics leading to evolution, or for that matter, leading to the life of any given organism.  But this type of dismissal, even from advanced thinkers such as Wilson, shows how far the scientific community still has to go in crossing the complexity barrier, and participating in that “marriage” of natural selection and complexity theory.

[1] See Kosse, K. (2001). “Some Regularities in Human Group Formation and the Evolution of Societal Complexity.” Complexity, 6(1 (2001)), 60-64, who calls for a “marriage between Darwinian theory and the emerging science of complexity.”

[2] Wilson, D. S. (1997). “Biological Communities as Functionally Organized Units.” Ecology, 78(7), 2018-2024.