In Real or Artificial Life, Is Evolutionary Progress in a Closed System Possible? What'sNEW | Lenski et al.

Assumptions are more striking than ideas — Alexander Hiam

Evolutionary progress in life on Earth is evident in the long series of steps that lead from prokaryotic life almost four billion years ago to the variety of multi-celled eukaryotic creatures with specialized organs, tissues, systems and features that exist here today. It is driven by the accumulation of new genes, the encoded instructions for life. We would like to understand this progress.

Energy reaches Earth from the sun, of course, but encoded instructions do not. We have long believed that evolutionary progress takes place in a biologically closed system, because we thought, until recently, that life could not survive in space. We thought that space was a perfect barrier to life, making the whole planet a closed biological system.

Today, however, we know that space is an imperfect barrier to life. We now know that cells can survive in space and could be delivered in viable form to Earth's surface (NASA, 1999). We now know that dormant bacterial spores can remain viable for at least 25 million years (Cano and Borucki, 1995); it is reasonable to suppose that they are immortal (Postgate, 1994). There is growing evidence that Mars once harbored bacteria, and that rocks containing them have reached Earth (McKay et al., 1996). It is no longer certain, nor even likely, that Earth's biological system is closed.

Closed-system demonstrations of evolutionary progress in biology are not difficult in principle, but they have not been convincingly done. The most ambitious demonstration to date is a series of experiments on E. coli that have cumulatively run for 24,000 generations. Although mutation and recombination were rampant, no new genes or suites of genes with new functions were reported to have evolved. Only microevolution or sideways adaptations by mutations that enabled, disabled, or slightly changed existing genes took place (Papadopoulos et al., 1999; Vulic et al., 1999).

Meanwhile, biologists are finding more and more evidence, like viral genes in humans (Sverdlov, 1998), indicating that the lateral transfer of genes is a ubiquitous process. The biological means to make evolutionary progress in an open system are becoming well known (Lake et al., 1999).

At this point, the case for evolutionary progress in a biologically closed system depends heavily on the remotest evidence of all, the new perfect barrier to life, the big bang. If the whole universe is a permanently closed system that began in a lifeless state a finite time ago, then evolutionary progress, including the origin of life, must have subsequently happened in it. But the big bang theory is plagued with frequent surprises (e.g. Glanz, 1998). In some versions, big bangs are preceded by other big bangs ad infinitum (Guth, 1997), and ways for life to persist through big bangs have been proposed (Frautschi, 1982; Krauss and Starkman, 1999). In any case, to understand evolutionary progress biology should be able to cite firmer and more immediate evidence than the big bang!

With its basis insecure and under revision, and with an alternative becoming apparent, the theory that life makes evolutionary progress in a closed system needs additional support.

Computers, like life, rely on encoded instructions. They also exhibit evolutionary progress. Accumulated improvements have made commercial software far more powerful today than only fifteen years ago. Of course, this evolution has occurred in an open system, because people installed the improvements. But computer experiments that attempt to model evolutionary progress in closed systems are under way (e.g. Ray, 1996). The work is called "artificial life" and various other names, and the experimental environment is not restricted to conventional software. Obviously, a closed-system model that exhibited lifelike, sustained evolutionary progress would have profound importance for biology. In fact, many closed-system computer models exhibit surprising behavior or solve preestablished problems. But in spite of much honest effort, none has achieved lifelike evolutionary progress. They all remain confined within their original parameters.

Nevertheless, computer scientists are confident that an unquestionable demonstration of evolutionary progress in artificial life is imminent, because they think they are only trying to model a phenomenon already proven in biology. Many biologists, on the other hand, are under the impression that computer models have already corroborated evolutionary progress in a closed system.

Yet the phenomenon has not been unequivocally demonstrated in either medium. Until it is, one can reasonably doubt that evolutionary progress in a closed system is possible, in real or artificial life.

Acknowledgments

What'sNEW

S. Ciliberti et al., "Innovation and robustnes in complex regulatory gene networks" [

text], p 13591-13596 v 104, Proc. Nat. Acad. Sci., USA, 21 Aug (online 9 Aug) 2007. To study innovation systematically, one needs to take the element of surprise out of it.
29 Jul 2007: The Limits of Organic Life in Planetary Systems
John Doyle and Marie Csete, "Rules of engagement" [text | Editor's Summary], p 860 v 446, Nature, 19 Apr 2007. New genes and pathways... can plug-and-play, as long as they obey protocols.
The Golem Project by Hod Lipson and Jordan B. Pollack, last updated 3 Sep 2001. "...We have concluded that merely more CPU is not sufficient to evolve complexity: The evolutionary process appears to be hitting a complexity barrier that is not traversable using direct mutation-selection processes...."
Wolfgang Banzhaf et al., "From artificial evolution to computational evolution: a research agenda" [abstract], doi:10.1038/nrg1921, p 729-735 v 7, Nature Reviews Genetics, Sep (online 8 Aug) 2006.
15 Apr 2006: The Evolution Prize will be launched hopefully at ALife X.
Roger Brent and Jehoshua Bruck, "Can computers help to explain biology?" [text], doi:10.1038/440416a, p 416-417 v 440, Nature, 23 Mar 2006.
5 Jan 2006: "Evolution in Action" was the number one "Breakthrough of the Year" according to Science.
Brig Klyce solicits Tom Ray's current opinion on this question in an open email, 31 Dec 2005.
31 Aug 2005: Americans think public schools should teach creationism alongside evolution.
10 Dec 2004: Evolution versus creationism was the topic on CNN last week.
26 Nov 2004: The evolution of a new fruitfly gene...
26 Sep 2004: An article promoting Intelligent Design...
19 Jun 2004: Darwinism's ability to produce evolutionary progress has not been demonstrated....
2002, December 31: No evolutionary progress in a closed system!
Scientists exposed as sloppy reporters by Hazel Muir, New Scientist, 14 Dec 2002. Is this how biologists and computer modelers became misinformed?
2002, May 9: Bet on sustainable evolutionary progress?
2001, November 21: The University of Oklahoma will probe for evolutionary progress in closed systems.
2001, October 9: Funds available for research.
A Scientific Critique Of Evolution by Dr. Lee Spetner — A creationist writer makes an informed case that Darwinian processes have not been shown to produce evolutionary progress. 25 February 2001.
2000, November 23: ...The Concept of Progress in Evolutionary Biology — book review.
Essay by Jon Richfield and exchange with Brig Klyce, mostly about progress in evolution (sometimes acrimonious), in "Replies," February-March 2000.
1999, November 22: GECCO-2000, July 8-12, in Las Vegas, NV.
1999, November 18: NASA's Center for Computational Astrobiology inaugurated today.

Lenski et al.

Christoph Adami, "Digital genetics: unravelling the genetic basis of evolution" [abstract], p 109-118 v 7, Nature Reviews Genetics, Feb 2006.
Carl Zimmer, cover story: "Scientists at Michigan State Prove Evolution Works" [text], p 28-36 v 26, Discover, Feb 2005. "Avida is not a simulation of evolution; it is an instance of it."
Chet Raymo, "Evolution was, and is, a great notion," The Boston Globe, 17 June 2003. "As these computer experiments continue — and this is not the first — the insights of Darwin and Wallace become ever more compelling."
Origin of complex functions? — Brig Klyce's letter to Nature, 17 May, and a response, 22 May 2003.
2003, May 11: Computer model evolves complex functions?
2003, February 4: The latest results from a closed-system biological experiment.
2003, January 26: "Evolving Inventions,"in Scientific American.
Claus O. Wilke et al., "Evolution of digital organisms at high mutation rates leads to survival of the flattest"[abstract], p 331-333 v 421 Nature 19 July 2001. "...Competition ...favour[ed] the genotype with the lower replication rate. These genotypes, although they occupied lower fitness peaks, were located in flatter regions of the fitness surface and were therefore more robust with respect to mutations."
Survival Of The Flattest, SpaceDaily.com, 23 July 2001.
Contacting Richard Lenski, in August 2000, was not fruitful.
1999, September 26: Experimental Evolution with Microbes and Molecules
1999, August 12: New computer model of evolution
1999, July 15: A Recent Issue of Science... [1st paragraph]

References

Cano, R. and M. Borucki, pp 1060-1064 v 268 Science, 1995.

Frautschi, Steven, pp 593-599 v 217, Science, 1982.

Glanz, James, pp 2156-2157 v 282 Science, 1998.

Guth, A., The Inflationary Universe, Addison-Wesley, 1997.

Hiam, A., "Obstacles to Creativity," The Futurist, October, 1998.

Krauss, Lawrence M. and Glen D. Starkman, pp 58-65 v 281, Scientific American, November 1999.

Lake, J. et al., pp 2027-2028 v 283 Science, 1999.

McKay, D. et al., pp 924-930 v 273 Science, 1996.

NASA's "Astrobiology Roadmap," 4 January 1999: http://astrobiology.arc.nasa.gov/workshops/1998/roadmap/

Papadopoulos, D. et al., p 3807 v 96, PNAS, USA, 1999.

Postgate, John, The Outer Reaches of Life, Cambridge University Press, 1994.

Ray, Thomas, "Artificial Life," 15 July 1996: http://www.hip.atr.co.jp/~ray/pubs/fatm/fatm.html

Sverdlov, Eugene, pp 1-6 v 428 Federation of European Biochemical Societies - Letters, 1998.

Vulic, M. et al. p 7348 v 96, PNAS, USA, 1999.