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."
Chordates are a phylum. Verterbrates are not a phylum, they are a subgroup of the chordate phylum. And, by the way, "phylum" is the singular, "phyla" is the plural.
I think it was about some article in Nature. If it were addressed to you, it's still in your message list. When you look at "my comments," click on "full" which is in the upper right corner of the screen. It will be there.
Well, what's the big deal? We all get called liars. If you didn't get the post pulled, I can't imagine who did. Such posts from that person are nothing new around here.
At one point, a pair of snakes came slithering down the ramp together. Noah addressed them as he had all the others: "Go forth and multiply!" The snakes looked at one another in embarassment, and then replied, "We can't. We're adders."
Well, this set Noah to thinking. He bid the snakes to wait there for a little while. Then he went down to the hold, gathered up his carpentry tools (left over from the big Ark-building endeavor 40 days and nights ago, I suppose), and then set off into the forest. He returned later dragging along a bunch of fallen logs.
Then there was furious activity: Noah was sawing, planing, hammering away at the logs. When he was finished, he presented to the snakes a newly built, rough-hewn table. Then he said to them again, "Go forth and multiply!"
"But we're adders!" the snakes moaned. Noah said, "Yes, but I've just built you a log table!"
What you have done here, in your usual jesuistic way, is substitute one field of discourse for another as suits your fancy. One may speak of a diode as an actual physical package you may hold in your hand, and solder into a circuit. One may also speak of the fundamental properties of a diode, as a mathematician would in defining it's properties. To a mathematician, (and this is whom you would ask in this discussion) a transister is two diodes close enough together for the quantum tunneling affect to take place, thereby rendering one of the diodes a controlling choke on the other diode's output. If you look at the math model, or you look at the blowup in your freshman engineering textbook, you will see that it is two diodes glued together. Anyone, even someone with as much weasel blood as you, can verify this in a few minutes in a library.
If you answer posts #1581 and #1579 in some sensible manner, I will once again answer this once again offered irrelevancy.
What you have done here is prove that you are a complete idiot. I wrote that something was something else in a sense (You apparently do not know what that means). The person to whom I wrote that replied that it was an "actuality" (his word) that a transistor was two diodes back-to-back. I replied that putting two diodes back-to-back did not make a transistor. I gave an actual example of soldering two diodes together, something that is done routinely every day in the construction of a bridge rectifier. You come back oblivious to the proper use of words and try to accuse me of following the "jesuistic way". Sir, what that points out is not my actions but rather your preoccupation with some deep seated resentment. Now get a life. I will not respond to such a blithering idiot. A junction transistor is "in a sense" two back-to-back transistors. And I quote you "One may speak of a diode as an actual physical package you may hold in your hand, and solder into a circuit. One may also speak of the fundamental properties of a diode, as a mathematician would in defining it's properties."
in a sense
adv : in some respects; "in a sense, language is like math" [syn: in a way]
| Source: WordNet ® 1.6, © 1997 Princeton University |
I'm sorry, but I saw that one coming from a mile away.....
You are now in the same rarified company as "Doctor Stocahstic" as being a purveyor of some of the worst puns ever to grace FR. Your contributiuons in this regard are, if I may be so bold as to say so, without equal. Congratulations!
;-)
"All that mattered was the defeat of the enemy. Inasmuch as all ethics were subordinate to "the larger political interest," Sidney and Bill were therefore perfectly aligned. And the deeper the stupid, petty lies of the President, the more vital it was for Sid to defend him. To any person with a moral compass outside of partisanship, this seems close to ... nuts --- It was."
Knee jerk science --- evolution !
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