Feb 12, 2008 9:09 AM

Complexity Theory Takes Evolution to Another Level

One hundred and ninety-nine years after Charles Darwin was born, and 149 years after he published On the Origin of Species, some scientists say that the theory of evolution is due for a revision. Not a religiously inspired revision — intelligent designers need not apply. Nobody suggests that genetic mutation and natural selection aren’t responsible […]

One hundred and ninety-nine years after Charles Darwin was born, and 149 years after he published On the Origin of Species, some scientists say that the theory of evolution is due for a revision.

Not a religiously inspired revision -- intelligent designers need not apply. Nobody suggests that genetic mutation and natural selection aren't responsible for the evolution of birds from reptiles or humans from tree-swingers.

But a growing number of scientists do say that neo-Darwinian evolution doesn't explain certain jumps in biological complexity: from single-celled to multicellular organisms, from single organisms to entire communities.

The jumps -- saltations, in complexity parlance -- appear to be non-linear emergent phenomena, the result of networked interactions that produce self-organization at ever higher levels. From this perspective, Darwinian evolution is a mechanism of a higher universal law, perhaps even a variant on the second law of thermodynamics.

I've got an article in the pipeline on the union of complexity theory and evolutionary biology, and over the next few days will publish outtakes from the interviews here. One interviewee was Carl Woese, a titan of 20th century microbiology, who with colleague George Fox reorganized the organismal kingdom from five branches to three.

Woese's experience with bacteria led him to look for an evolutionary framework larger than that provided by Darwin and his intellectual descendants. Bacteria -- which may account for up to half of Earth's biomass -- swap genes without reproducing; with millions residing in a teaspoon of seawater, Woese sees them in terms of networked communities rather than individual cells, and interprets their evolutionary history as driven by the non-linear self-organization that's now being studied at all biological scales.

It's a rough analogy, but if you knew a lot about individual stars, it's doubtful you could predict the existence of galaxies. When the larger unit is sufficiently integrated, the individual unit is not as individualistic as you think. [...]
The prokaryote concept is a bunch of crap, and stood in the way of the development of microbiology for 80 years. Only now is microbiology emerging, and people like you can hear what I'm saying. These concepts are not based on the individual organism, the individual species. The individual unit in microbiology is not the cell; the primary unit is the organismal community. Cells develop in organismal community; they don't give rise to them; the evolution of the cell takes place in the framework of this community. The individual organism more tightly coupled to the whole than we recognized. [...]
The world of animals and plants began with eukaryotic cells, as you know; what the history of the development of the eukaryotic cell is, I don't know, but it's clearly a more complex entity than either the archaea or the bacteria. There's something we're going to find about the eukaryote that's very special, and captures the essence [of emergence and complexity at the heart of evolution.] [...]
Evolution is a process that manifests itself at a level-independent way. You've got these basic cells, viruses along with them -- and then the multicellular world, the same evolutionary scenario played out, but the dynamics are shown to be the same; then you go to society and see the same dynamic playing out again -- but it's not the darwinian dynamic. It's the pre-Darwinian dynamic, when individuality had little significance, and everything was in distributed interaction. [...]
Saltations are state changes. The simple example would be something like a magnet heated up to a high temperature where the iron dissolves;
the magnetic properties are gone; then when you reach a critical temperature in cooling down, the magneticism reappears in a very short temperature change.
The property is gone in the individual iron atoms, but when they behave collectively, you see the property of the whole. That's a very simple example.
The microbial world is where I work; [saltational evolution] predicts that there should be properties of the collective thing, that arise as the thing collects. [...]
Twentieth century biology was structured according to a linear
Newtonian worldview. Linear thinking is not the kind of thinking that's needed to study evolution. It doesn't help you understand the nature of systems. Molecular biologists were so set about linearity that when the gene came along, they took the gene to be the be-all and end-all of basic biology. That comes out of thinking in terms of particles and linear interactions.... I see evolution as the quintessential non-linear dynamics problem.

It's heady stuff, and a lot of the hard science that Woese explained didn't come out well enough in transcription to make sense here. To understand him more completely I highly recommend reading "A New Biology for a New Century," published in 2004 in
Microbiology and Molecular Biology Reviews. It's a visionary blend of history and microbiology, and shows that Woese is that rarest of all organisms: a brilliant scientist who can really write.

Update: a follow-up post, "Evolution as Biological Thermodynamics"

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