Sunday, November 16, 2008

A New (er, Old) Meme on Evolution: It's Not Random, It’s Self-Correcting, and Wallace Was Right

Complexity vs. the “Blind Watchmaker": (Credit: iStockphoto/Sven Klaschik)

Princeton scientists say they’ve found chains of proteins that act like “adaptive machines, possessing the ability to control their own evolution.” These proteins, according to the scientists, are found in nearly all living organisms.

“The discovery answers an age-old question that has puzzled biologists since the time of Darwin,” says researcher Raj Chakrabarti in Science Daily. “How can organisms be so exquisitely complex, if evolution is completely random, operating like a
‘blind watchmaker’? Our new theory extends Darwin’s model, demonstrating how organisms can subtly direct aspects of their own evolution to create order out of randomness.”

I’m out of my element here with the science, but apparently the research zeroes in on a complex of proteins located in the mitochondria and offers “evidence of a hidden mechanism guiding the way biological organisms respond to the forces of natural selection.” Essentially, researchers say they’ve found that certain kinds of biological structures can “steer the process of evolution toward improved fitness.” (“Certain” = most.)

Princeton researchers: Herschel Rabitz (left) and Raj Chakrabarti are part of the research team. (Credit: Brian Wilson)

The researchers mention Darwin, but they really cite Alfred Wallace, saying that their laboratory efforts confirm an idea “first floated” by him in an 1858 essay. Unlike Darwin, they explain, Wallace believed that species themselves may develop the capacity to respond optimally to evolutionary stresses:
Wallace had suspected that certain systems undergoing natural selection can adjust their evolutionary course in a manner “exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident.” In Wallace’s time, the steam engine operating with a centrifugal governor was one of the only examples of what is now referred to as feedback control. Examples abound, however, in modern technology, including cruise control in autos and thermostats in homes and offices.

The researchers, having given credence to Wallace’s view, are now working to formulate a general theory that they’re calling “evolutionary control,” what they suspect will be the underlying cause for the self-correcting behavior in the protein chains they studied. They define this control theory as something that offers a direct explanation for an otherwise perplexing observation and indicates that “evolution is operating according to principles that every engineer knows.”

According to the Princeton news report,

Applying the concepts of control theory, a body of knowledge that deals with the behavior of dynamical systems, the researchers concluded that this self-correcting behavior could only be possible if, during the early stages of evolution, the proteins had developed a self-regulating mechanism, analogous to a car's cruise control or a home's thermostat, allowing them to fine-tune and control their subsequent evolution.

In this paper, we present what is ostensibly the first quantitative experimental evidence, since Wallace’s original proposal, that nature employs evolutionary control strategies to maximize the fitness of biological networks.”
Laura Moorhead

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