Posted on 05/08/2003 10:11:06 AM PDT by Nebullis
Arlington, Va.—If the evolution of complex organisms were a road trip, then the simple country drives are what get you there. And sometimes even potholes along the way are important.
An interdisciplinary team of scientists at Michigan State University and the California Institute of Technology, with the help of powerful computers, has used a kind of artificial life, or ALife, to create a road map detailing the evolution of complex organisms, an old problem in biology.
In an article in the May 8 issue of the international journal Nature, Richard Lenski, Charles Ofria, Robert Pennock, and Christoph Adami report that the path to complex organisms is paved with a long series of simple functions, each unremarkable if viewed in isolation. "This project addresses a fundamental criticism of the theory of evolution, how complex functions arise from mutation and natural selection," said Sam Scheiner, program director in the division of environmental biology at the National Science Foundation (NSF), which funded the research through its Biocomplexity in the Environment initiative. "These simulations will help direct research on living systems and will provide understanding of the origins of biocomplexity."
Some mutations that cause damage in the short term ultimately become a positive force in the genetic pedigree of a complex organism. "The little things, they definitely count," said Lenski of Michigan State, the paper's lead author. "Our work allowed us to see how the most complex functions are built up from simpler and simpler functions. We also saw that some mutations looked like bad events when they happened, but turned out to be really important for the evolution of the population over a long period of time."
In the key phrase, "a long period of time," lies the magic of ALife. Lenski teamed up with Adami, a scientist at Caltech's Jet Propulsion Laboratory and Ofria, a Michigan State computer scientist, to further explore ALife.
Pennock, a Michigan State philosopher, joined the team to study an artificial world inside a computer, a world in which computer programs take the place of living organisms. These computer programs go forth and multiply, they mutate and they adapt by natural selection.
The program, called Avida, is an artificial petri dish in which organisms not only reproduce, but also perform mathematical calculations to obtain rewards. Their reward is more computer time that they can use for making copies of themselves. Avida randomly adds mutations to the copies, thus spurring natural selection and evolution. The research team watched how these "bugs" adapted and evolved in different environments inside their artificial world.
Avida is the biologist's race car - a really souped up one. To watch the evolution of most living organisms would require thousands of years – without blinking. The digital bugs evolve at lightening speed, and they leave tracks for scientists to study.
"The cool thing is that we can trace the line of descent," Lenski said. "Out of a big population of organisms you can work back to see the pivotal mutations that really mattered during the evolutionary history of the population. The human mind can't sort through so much data, but we developed a tool to find these pivotal events."
There are no missing links with this technology.
Evolutionary theory sometimes struggles to explain the most complex features of organisms. Lenski uses the human eye as an example. It's obviously used for seeing, and it has all sorts of parts - like a lens that can be focused at different distances - that make it well suited for that use. But how did something so complicated as the eye come to be?
Since Charles Darwin, biologists have concluded that such features must have arisen through lots of intermediates and, moreover, that these intermediate structures may once have served different functions from what we see today. The crystalline proteins that make up the lens of the eye, for example, are related to those that serve enzymatic functions unrelated to vision. So, the theory goes, evolution borrowed an existing protein and used it for a new function.
"Over time," Lenski said, "an old structure could be tweaked here and there to improve it for its new function, and that's a lot easier than inventing something entirely new."
That's where ALife sheds light.
"Darwinian evolution is a process that doesn't specify exactly how the evolving information is coded," says Adami, who leads the Digital Life Laboratory at Caltech. "It affects DNA and computer code in much the same way, which allows us to study evolution in this electronic medium."
Many computer scientists and engineers are now using processes based on principles of genetics and evolution to solve complex problems, design working robots, and more. Ofria says that "we can then apply these concepts when trying to decide how best to solve computational problems."
"Evolutionary design," says Pennock, "can often solve problems better than we can using our own intelligence."
You've noticed that, have you? That's because there's this sort of implicit assumption on the other side of the aisle that there are precisely two possible explanations for the origin of life - Biblical special creation, and evolution via natural selection. Therefore, the idea is that by poking enough holes in evolutionary theory, Biblical special creation becomes the default explanation. The fact that this is a false dichotomy and the fact that there is no such thing as a default explanation in science does not enter into the thought process, apparently. Theories are evaluated in light of one another, and not strictly on their own merits - the accepted theory is the theory that explains the facts better than all the rest, but obviously creationists are not particularly prepared to put their pet theory side-by-side with evolutionary theory, so that we can evaluate which one is really the stronger theory - I suspect that they know in their hearts that creationism could never survive such a comparison, and so they forswear an honest and fair fight between the two theories in favor of what can reasonably be described as a series of drive-by shootings.
That being said, Andrew is much too clever to be boxed into Biblical literalism in creation, or any other variety of universal special creation theory, which, if you drag his counter-theory out of him, I think you will see. For reasons that are largely opaque to everyone else, however, he likes to give aid and comfort to Biblical literalists and their ilk, despite not actually believing in that sort of thing himself.
Well, I'd say it would be a good thing, if, in fact, they didn't. I'm inclined to think that a good general characterization of the things you are describing is reduction to machine-like behavior of humans, who, when they are up to snuff, know better.
CB, this thread is about programming. No one is even talking about the actual source of this thread. I commented on what one of the principles of the article stated and was leventually ed to a "circuit challenge". These thread are put up for comment and they have a theme. I am now engaged in a discussion about a peripheral yet closely related item. If you don't like it then I suggest you don't participate.
You said there were no "in-betweens" so I offered you a link that indicates there are many. You have no response to this, yet you accuse me of selective reading. I assume that you will continue to read your favorite sources which claim there are no "in-betweens." No selectivity there.
My teachers have failed me?
Yes. In any event, welcome to FreeRepublic.
You are correct. I am not a literalist in relation to portions of the Holy Bible.
Indeed, and don't ever let me catch you asserting that you know both the position and momentum of a particle to the same degree of precision ;)
Perhaps that's because thay have no beliefs? We have been trying to get some of the Creationists to just state simple things such as: how old do they believe the earth to be. The Kefauver Committee got more responses.
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