Trilogy of Life

I mentioned the “trilogy of life” proposed by Capra and Luisi three blog posts ago. Today I follow up with their three “perspectives” of life – before adding a fourth. (For the interested reader, this is 14.3 in their Systems View of Life book.)

 

The first perspective is structure. We can think of it as the physical “stuff” of matter – the atoms, ions, and molecules that make up living systems. The second perspective, organization, has to do with specific arrangements of structures. The authors put it this way: “The structure of a system is the physical embodiment of its pattern of organization.” Organization, then, is an “abstract mapping of relationships” between the physical structures. Organization is associated with function. They use the components of a bicycle (frame, pedals, wheels, chain, etc) – but not what they’re physically made of – as an analogy for the organization of what makes up a bicycle. In contrast, the structure of the bicycle can be made of different materials with different shapes and sizes. So bicycles might look very different structurally, but we can still identify them all as bicycles functionally.

 

What is the connection between structure and organization? In the bicycle, it’s the blueprints of the designer. Blueprints need not be “physical”, designs can live abstractly in the mind of a designer. In living cells, the fundamental unit of biological (as opposed to artificial) life, the connection is process – the third perspective. The authors call it “the activity involved in the continual embodiment of the system’s pattern of organization.” (We’ve now seen the idea of embodiment come up twice. We’ll get back to it.)

 

So what is a living system? The authors integrate these three interdependent perspectives: “[The] pattern of organization is that of a self-generating (autopoietic) network… the material structure of a living system is a dissipative structure – that is, an open system operating far from equilibrium… living systems are cognitive systems in which the process of cognition is closely linked to the pattern of autopoiesis.” You might be surprised to see the word “cognition”. While this may conjure notions of human cognition, the authors use the term much more broadly. Process, the third perspective, may involve chemical reactions, or the emergence of higher order organization in a cybernetic system.

 

As a chemist, it’s easy for me to think about structure, the first perspective. Function is a little trickier and I suppose my conception of this is mainly Aristotelian. In my jumbled mind, it’s part organization and part process, depending on the system “level” that you’re analyzing. While there may be no privileged level of causation, I find myself as a chemist constantly going back to molecular-level structure. Maybe because that’s what I find the most comfortable and what I think I know most about (I might be wrong). Capra and Luisi address this head-on. Here’s what they have to say.

 

“To give equal importance to each of these perspectives is difficult for most scientists because of the persistent influence of our Cartesian heritage. The natural sciences are supposed to deal with material phenomena, but only the structure perspective is concerned with the study of matter. The other two deal with relationships, qualities, patterns, and processes, all of which are nonmaterial. Of course, no scientist would deny the existence of patterns and processes, but most scientists tend to think of a pattern of organization as an idea abstracted from matter, rather than a generative force. To focus on material structures and the forces between them, and to view the patterns of organization resulting from these forces as secondary phenomena have been very effective in physics and chemistry, but when we come to living systems this approach is no longer adequate. The essential characteristic that distinguishes living from nonliving systems… is not a property of matter… it is as specific pattern of relationships among chemical processes. Although these processes produce material components, the network pattern itself is non-material.”

 

All that being said, the nonmaterial second and third perspectives are embodied. In a living system, you can’t cleanly separate from the first perspective. I’ve been grappling with this idea for a while, especially since my reading diet often includes neuroscience and cognitive processes related to learning. What does it mean that cognition is embodied? Can it be disembodied? Can it be translocated to a different type of embodiment? As a computational chemist, there’s a clear distinction between how I think about hardware and software. I suppose one could conceive forms of artificial life that maintain such a distinction.

 

Even as I’ve been pondering this wrinkle, the authors throw in a fourth perspective. They call it meaning – their “shorthand notation for the inner world of reflective consciousness”. I don’t quite grasp their meaning here (pun intended), but it has something to do with extending living systems to include social relations. The remainder of the book chapter goes into social theory. I think I understand what they’re saying, at least at the surface level, but I suspect that my non-expertise in this area means I’m missing a whole lot. [LINK] Hard to say. They do have one picture illustrating the “interconnectedness” of these four perspectives as the corners of a tetrahedron. This made me think of tetrahedrally-shaped methane with carbon in the center. Carbon, central to life, is perhaps not just a carrier?