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."
There are loads of transitionals. Check this out for a sampler, and discover how your teachers have failed you: Transitional Vertebrate Fossils FAQ.
We now have Cro-magnon and modern man living at the same time. Science is still trying to explain this one. In France modern man was found existing in the lowlands and Cro-man in the highlands. When scientists are asked they say they are working it out.
I think you mean Neanderthal. Cro-magnon is pretty much us. Not a significant lapse in reasoning on your part, but it does indicate a lack of familiarity with the subject matter.
But they have said so far that at the moment it seems that modern man just "appeared" out of nowhere.
No, that's your position.
As to evolution, I have seen no proof that something evolved.
You won't find proof. But you will find loads of evidence. What does the fossil record mean to you?
I do however see evidence of things created.
Wow. Stuff just pops into existence, like from a Star Trek transporter? Really?
Disprove to me the missing "Creator"
I have no interest in that one.
A lot of people investing in biotech will be disapointed...
I'm guessing the real mortality rate is the same as for the general population. One fatality per customer...
And where's the blue food?
:^)
San Francisco
It's so limiting having just two genders. You don't have enough adults around for bridge, you don't have a voting quorum, you don't have sufficient witnesses as to what was said in the heat of the moment, and you only have boring old binary homo- and hetero- sexual lovemaking. Plus courtship can't consume all your waking hours just for the scheduling alone, leaving people to wonder the street looking for amusement to fill their idle moments and generally getting into trouble. You know who I blame for this mess? Conservatives.
A list of green mammals: http://www.strangeark.com/biofortean/green.html
Does it have to be entirely green? More than 50% green by surface area?
As I said, they were not references to the topic, however, they refer to something, therefore, they are references.
I already know the 9 transistor circuit design. It is not a 9 transistor circuit as designed. It was a 5 transistor, 4 diode circuit in the patent. I read the patent.
This is not about me. I have to prove nor provide evidence for what I believe. I argue the points asserted by others. The assertion, at the moment is that a evolved piece of junk circuit performs better in an unspecified way than a patented circuit. I asked for evidence. That evidence has not been produced.
Look at the patented circuit. It has 5 transistors and 4 diodes. The circuit reproduced in the article has 9 transistors. It uses 4 transistors as diodes thus it models the original circuit but it is not the original circuit. Why do you suppose they did not use diodes in the evolution?
Why the inordinate fascination with my beliefs? The argument concerns what is demonstrated. I still see nothing but an assertion about a kludge circuit. The kludge circuit most certainly outperforms the patent circuit in entropy production but I have no evidence that it better performs the cubic function over the frequency range specified in the patent.
Further, the patented circuit makes reference to another patented circuit(6,002,291) involving 9 transistors and a resistor which "combines the outputs from three differential pairs of transistors to generate an output current that varies in a cubic-type manner in response to the input voltage. "
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