Re: News: Evolution's new wrinkle.

geoproc@xxxxxxxxxxx wrote:
On 12 Nov, 00:07, Ye Old One <use...@xxxxxxxxx> wrote:
Evolution's new wrinkle
Proteins with cruise control provide new perspective

http://www.eurekalert.org/pub_releases/2008-11/pu-enw111108.php

A team of Princeton University scientists has discovered that chains
of proteins found in most living organisms act like adaptive machines,
possessing the ability to control their own evolution.

The research, which appears to offer evidence of a hidden mechanism
guiding the way biological organisms respond to the forces of natural
selection, provides a new perspective on evolution, the scientists
said.

The researchers -- Raj Chakrabarti, Herschel Rabitz, Stacey Springs
and George McLendon -- made the discovery while carrying out
experiments on proteins constituting the electron transport chain
(ETC), a biochemical network essential for metabolism. A mathematical
analysis of the experiments showed that the proteins themselves acted
to correct any imbalance imposed on them through artificial mutations
and restored the chain to working order.

"The discovery answers an age-old question that has puzzled biologists
since the time of Darwin: How can organisms be so exquisitely complex,
if evolution is completely random, operating like a 'blind
watchmaker'?" said Chakrabarti, an associate research scholar in the
Department of Chemistry at Princeton. "Our new theory extends Darwin's
model, demonstrating how organisms can subtly direct aspects of their
own evolution to create order out of randomness."

The work also confirms an idea first floated in an 1858 essay by
Alfred Wallace, who along with Charles Darwin co-discovered the theory
of evolution. 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 research, published in a recent edition of Physical Review
Letters, provides corroborating data, Rabitz said, for Wallace's idea.
"What we have found is that certain kinds of biological structures
exist that are able to steer the process of evolution toward improved
fitness," said Rabitz, the Charles Phelps Smyth '16 Professor of
Chemistry. "The data just jumps off the page and implies we all have
this wonderful piece of machinery inside that's responding optimally
to evolutionary pressure."

The authors sought to identify the underlying cause for this
self-correcting behavior in the observed protein chains. Standard
evolutionary theory offered no clues. 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. The scientists are
working on formulating a new general theory based on this finding they
are calling "evolutionary control."

The work is likely to provoke a considerable amount of thinking,
according to Charles Smith, a historian of science at Western Kentucky
University. "Systems thinking in evolutionary studies perhaps began
with Alfred Wallace's likening of the action of natural selection to
the governor on a steam engine --- that is, as a mechanism for
removing the unfit and thereby keeping populations 'up to snuff' as
environmental actors," Smith said. "Wallace never really came to grips
with the positive feedback part of the cycle, however, and it is
instructive that through optimal control theory Chakrabarti et al. can
now suggest a coupling of causalities at the molecular level that
extends Wallace's systems-oriented approach to this arena."

Evolution, the central theory of modern biology, is regarded as a
gradual change in the genetic makeup of a population over time. It is
a continuing process of change, forced by what Wallace and Darwin, his
more famous colleague, called "natural selection." In this process,
species evolve because of random mutations and selection by
environmental stresses. Unlike Darwin, Wallace conjectured that
species themselves may develop the capacity to respond optimally to
evolutionary stresses. Until this work, evidence for the conjecture
was lacking.

The experiments, conducted in Princeton's Frick Laboratory, focused on
a complex of proteins located in the mitochondria, the powerhouses of
the cell. A chain of proteins, forming a type of bucket brigade,
ferries high-energy electrons across the mitrochondrial membrane. This
metabolic process creates ATP, the energy currency of life.

Various researchers working over the past decade, including some at
Princeton like George McClendon, now at Duke University, and Stacey
Springs, now at the Massachusetts Institute of Technology, fleshed out
the workings of these proteins, finding that they were often turned on
to the "maximum" position, operating at full tilt, or at the lowest
possible energy level.

Chakrabarti and Rabitz analyzed these observations of the proteins'
behavior from a mathematical standpoint, concluding that it would be
statistically impossible for this self-correcting behavior to be
random, and demonstrating that the observed result is precisely that
predicted by the equations of control theory. By operating only at
extremes, referred to in control theory as "bang-bang extremization,"
the proteins were exhibiting behavior consistent with a system
managing itself optimally under 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," Chakrabarti said. "Control theory offers a
direct explanation for an otherwise perplexing observation and
indicates that evolution is operating according to principles that
every engineer knows."

The scientists do not know how the cellular machinery guiding this
process may have originated, but they emphatically said it does not
buttress the case for intelligent design, a controversial notion that
posits the existence of a creator responsible for complexity in
nature.

Chakrabarti said that one of the aims of modern evolutionary theory is
to identify principles of self-organization that can accelerate the
generation of complex biological structures. "Such principles are
fully consistent with the principles of natural selection. Biological
change is always driven by random mutation and selection, but at
certain pivotal junctures in evolutionary history, such random
processes can create structures capable of steering subsequent
evolution toward greater sophistication and complexity."

The researchers are continuing their analysis, looking for parallel
situations in other biological systems.

--
Bob.

The ID chaps are already loving this. Indeed, it does seem to read
like their stuff; exquisite machinery, fine tuning, etc... what does
this really mean? They even say 'randomness could not have caused
this', which we know to be a statement beloved of creationists. The
only bit which made me realise it's not related to ID was where they
talked about doing experiments and gathering data.

No, they also said that a chief aim is to identify principles of *self-organization*. Self-organization doesn't require a Grand Designer to do the organizing from the outside.


--
Steven L.
Email: sdlitvin@xxxxxxxxxxxxxxxxxxx
Remove the NOSPAM before replying to me.

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