

When Guy Hoelzer runs computer simulations of organisms living in the modeling equivalent of a featureless plain, he sees them break into different species – *even though there's no reason for natural selection to take place. *

That preliminary but tantalizing finding hints at some larger phenomenon driving the mechanisms of neo-Darwinian evolution. Hoelzer thinks the phenomenon is self-organization: combine energy with complex networked interaction and order will emerge.

In the abstract of "On the logical relationship between natural selection and self-organization," published in 2006 in the Journal of Evolutionary Biology, he described natural selection as "a mechanism that coordinates the coevolution of species in an ecosystem to effectively capture, process and dissipate solar energy into the earth's shadow ... an emergent process founded on the same thermodynamic imperatives that are thought to underlie all self-organization."

I came across that paper while researching an upcoming article on the application of complexity theory to evolutionary biology, and was fortunate enough to interview Hoelzer. (Another interview, with microbiology titan Carl Woese, came out in Wired Science yesterday.) Here's what he said:

The idea of self-organization as a natural engine of activity seems like a relevant thing for evolutionary biology. But at least in this country, I detected a large resistance to this idea from evolutionary biologists devoted to exploring Darwinian theories of evolutionary biology and adaptation. I never saw them as being in conflict – but that was the feedback I was getting. In the paper we explored the relationship and came to conclusion that Darwinian natural selection is a mechanism of self-organization in the biosphere. We saw these concepts as tightly linked: the idea of natural selection embedded within self-organization. The way I think about it in the biological sense is from thermodynamic point of view, which is the same way chemists think of self-assembly in molecules. It's a somewhat outcome-driven process: the precise mechanisms that get you to that outcome are less fundamental than the outcome achieved. You're maximizing the rate of entropy production and so on. In a biological system, if the function is to break down gradients and increase the rate of entropy production, natural selection is an effective evolutionary way to get there. It coordinates the ecological roles of species such that the ecosystem persists and processes a great deal of energy. This particular perspctive works at all scales. That in fact is part of the idea here: to extend thermodynamic thinking up to the scale of ecosystems and the biosphere. It's not inconsistent with the Gaia idea. I'm doing some very early research at the single-species level, where

I'm doing computational modeling of population genetics. It involves a different approach from traditional mathematical modeling: it allows us to spread a population across a large [and uniform] space in the computer model. One thing I find is that as mutation occurs in the system, it drives genetic divergences in a spatially localized way. I get spacial self-organization. One sub-species dominates in one place;

a different sub-species in another place. If I allow genetic incompatibilities to evolve through mutation, we get speciation.

Speciation is a process of self-organizaiton of the gene pool; in this case, it's not driven by adaptation to environmental conditions. It's as if – to put in teleological language – its as if these populations are inherently, internally, a machine of diversification that creates types that are spatially localized. If you add environmental variables, does it chage? It's early in the project – but I want to address that. There's no doubt that environmental variation will impact the process, but I doubt that it will overwhelm it. I think this internal dynamic, which is a matter of self-organization, is omnipresent and universal. I see it as physics – my own point of view is that chemistry is a subset of physics, and biology a subset of chemistry, so these scales of organization of matter are all aspects of self-organization and driven by physics. What are the drivers? From a thermodynamic perspective, if you have a dynamical system composed of lots parts, it seems to rather generically have this tendency to self-organization.

That builds higher levels of organizations, from (perhaps) strings to subatomic particles up to macromolecules, to biomolcules, cells, multicellular organisms, species, ecosystems and so on. I think there's quite a wave of work being done in this area that may not be appreciated by some evolutionary biologists until it's washed over the field. I think we'll wake up one day and turn around and say,

"Wow! We lived through a revolution in our thinking of evolution. We won't realize until it's done. But I don't see ideas about self-organizing complex systems as competing with our traditional Darwininan evolution, but extending them and putting them into a thermodynamic context. I'd hope that my colleagues would see this as a point of view for deepening understanding.

If this interests you, be sure to check out the Carl Woese interview. Another Woese tidbit: he called evolution a variation on the second law of thermodynamics, of the progress from high to low universal energy, to a point where even atoms fall apart. Maybe that's not what's going to happen, he said: maybe "the universe is going to decay into all these wonderful sculptures."

When would it stop, I asked?

"When does an algorithm stop?" replied Woese. "Certain algorithms continue to change in their state. They go on and on. You wouldn't ask when an algorithm has run its course. Evolution is like that."

Image: The current evolutionary stage of our Charles Darwin Photoshop Tennis Contest

See Also:

Science Journalism 2.0: Pop the hood on Wired Science....