How and Why

A decade ago, I read Jeffrey Wicken’s Evolution, Thermodynamics, and Information. I should say I tried to read it, but didn’t understand it. Now I’m trying again, and with some Ganti and Rosen under my belt, it’s making more sense. Like Ganti and Rosen, Wicken’s ideas were outside of the mainstream. The trio are pioneers – not understood during their time – but they’ve paved the way to a more comprehensive view of what it means to be a living system, and given us glimpses of what it might mean to transition from non-life to life.

 

Wicken’s goal is to bring together the three strands of thermodynamics, evolution, and information. Each area has its own historical development. They might make reference to each other, or more often cause confusion perhaps because we don’t quite understand any of the three well enough to forge deep connections among them. Wicken begins with the distinction between operation and genesis – essentially how and why. The two can be separated cleanly for machines: One can explain the cause and effect processes as the machine proceeds through its mechanism of operation. As to the purpose of the machine – its genesis – a reason for its existence and why it was built is external to the machine itself.

 

For an organism, on the other hand, operation and genesis are not so easily separable. We kinda sorta talk about them separately (yet in parallel), but how they intertwine is a trickier business. Wicken’s one-sentence summary: “It is characteristic of natural organizations from organisms to societies that their existences are inseparable from their operations as informed dissipative structures.” There’s a lot packed into that sentence because it adds three new pieces to the story in the last three words: information, dissipation, structure.

 

How do we even begin to untangle this? Wicken’s approach is to follow the energy flow. For that, one has to begin with thermodynamics. He will expand on this in detail, but here’s his pithy encapsulation: “All irreversible processes result from the disequilibrium brought about by cosmic expansion, between potential and kinetic forms of energy. Energy flows occurring under the impress of this disequilibrium have predictive consequences with respect to the overall form of evolution.” This will involve things I’ve mentioned before in a previous blog post: The disequilibrium comes because radiant energy from the sun hits our planet, and thanks to carbon chemistry, this energy is dissipated as heat because outer space is cold! Energy flows from source to sink with life in-between to dissipate it.

 

But the sun’s rays also fall on other planets and moons and there’s no life there that we know of – so we need to figure out how and why the environmental constraints of planet Earth allowed for the evolution of life. Thus is born a research program. I like Wicken’s description: “Research programs are conceptual spaces in which theories are nurtured, examined, and given room to grow. They can therefore only be as good as their metaphysical suppositions, which must be carefully spelled out. So too must language, terms, and definitions.” Wicken will do this throughout his book, but here’s his research program in his own words: “… to provide unifying principles for evolution – from the prebiotic generation of molecular complexity through the self-organization of living systems through their phylogenetic diversification.”

 

In discussing reductionism, Wicken writes: “Whenever one attempts to explain a phenomenon in terms of something else, it is with the presumption that the ‘something else’ is more general, more basic than the phenomenon at hand. Bringing one discipline into the explanatory orbit of the other is theory reduction… Those who believe that living systems can be explained exhaustively in terms of present physics and chemistry are ontological reductionists. Ontological reductionism has little to recommend it biologically. Organisms are organized wholes, not sums of molecular parts. The most conspicuous triumphs in the application of reductionist methodology… biochemistry and molecular biology – disciplines whose major foci have concerned the study of parts and processes or organisms in isolation from organizational settings… a willingness to whittle down the richness of the organic world to one of nuts and bolts.”

 

And this is why Wicken wants to bring in thermodynamics: “A virtue of the thermodynamic approach is that it does not lend itself to talking about chemical parts. Thermodynamics is a science of systems, dealing more with processes than static elements… Life can’t however be reduced to thermodynamics…” The second law of thermodynamics is often quoted by proponents and antagonists of the theory of biological evolution, and the common understanding of entropy relates it to order and disorder. Wicken wants to carefully define his terms and makes a distinction between order and organization. Order has to do with how. Organization has to do with why. Here is how he describes it:

 

“Organisms are not only systems of very high potential energies compared with equilibrium systems of the same composition; they are also extremely ordered, low-entropy systems. Low entropy is of itself of little biological concern [e.g. inorganic crystals are highly ordered]… Organization involves function, and the physical sciences don’t deal with function… Organized systems are characterized by structural relationships that require information for their specification… When we talk about a ‘well-organized system we are referring to how effectively it carries out certain activities, rather than to specific structural factors internal to the system. Yet, function depends on the existence of structural factors, and quantification requires that organization be looked at from their vantage point… Degree of organization would then be measured by the degree of constraint, by the extent to which interactions between components limit their individual degrees of freedom.”

 

That last sentence is essentially the thesis of Terence Deacon’s Incomplete Nature, except Wicken is both clearer and more concise despite his book being 35 years older. Wicken carefully defines constraints, and ties them to function and information. Two properties of constraints: degree and complexity. This allows him to distinguish machines and organisms: “Machines are organized for external functions, which means that their operations can be kept distinct from their existences. This allows machines to be equilibrium organizations: there is no need for them to degrade free energy to maintain themselves. This is not the case with organisms…”

 

Wicken continues: “There are two ways in which the elements of a physical system can be arranged nonrandomly. One is according to internal patterns or statistical biases; the second is according to functional considerations. The former expresses order, the latter organization and functional information. That biological organization is ordered as well as information-rich expresses a unique feature of living systems that that the machine world does not share… But at the molecular level, order and informational-richness stand in mutual opposition: order requires pattern, periodicity, or a reduction of combinatorial options; informational capacity decreases as these are imposed.” (Wicken defines order in terms of information compressibility, and complexity as “the measure of information required to uniquely specify the elemental relationships of structured systems.”)

 

Entropy lies at the heart of quantifying order and information. But like other very general concepts such as Energy and Life, it is tricky to define. Wicken distinguishes Boltzmann entropy from Shannon entropy, and discusses why they are sometimes conflated even though there are significant differences in how they are defined. (They share equations that look similar.) This provides a way to quantify the ‘how’ in terms of statistics and probability calculations, but the ‘why’ remains elusive. Wicken writes: “Information content depends on complexity but is not coextensive with it.” He will attempt to connect the how and why, but that’s the subject of a future blog post.