Skip to comments.Artificial Life Experiments Show How Complex Functions Can Evolve
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."
I made the original statement. It was you that started the argument about it by accusing me of being a troll in making the statement. Now you say we agree and further say this
Give it up, son. You're just making a monumental ass of yourself.
Your statement actually describes yourself.
In a sense, you should insist on a refund. A transistor is a transistor. Absent the potential of a bias on the base your "back to back diodes" are as useless as a tit on a bull.
That's a nice straw man you've got there. "Absent the potential of a bias on the base" my hind end. Yeah, and "absent a battery a radio is just a hunk of metal and plastic". Like that disproves that radios work? Your squirming aside, if you take two PN junctions (diodes) and join them P-to-P or N-to-N, you will indeed have constructed a working transistor (although not a practical one if the middle of the "sandwich" is too thick). I presented specific facts and argument in the post to which you are responding, and I note you haven't attempted to refute a single one of them -- the best you can do is mouth off and make personally insulting remarks. Typical.
Take your sophistry elsewhere, we're not in the market today.
Did you take a course on "bull" in college as well? I hope the doping lecture was for the benefit of the general public because if it was intended for me, I can only chuckle.
I'm sure that *is* all you can do. Many of the rest of us are capable of a higher level of discourse, however.
I don't know what your problem is, but kindly do not continue to share it with us unless you've got something worthwhile to add to the conversation.
No doubt that is how you use it or many others. But then why address it to all, more than one, or any other specific person(unless it is just convenient) when it is much easier to just leave the "to line" blank?
It seems to me that part of judging the quality of arguments involves some knowledge of the topic at hand. (This is not a criticism of you, merely a statement of opinion.)
You don't have the requisite male anatomy to admit when you're wrong.
A battery is the source of potential dipstick, the base or gate of a transistor is an inherent component of same.
I repeat, get a refund forthwith.
I studied college level EE for five years, but that was 30 years ago, and I've been doing mostly micro-electro-mechanical systems (MEMS) for the last 20 years.
Like General_re, I've forgotten most of what I knew.
The core argument isn't a quibble about diodes and transisitors, it's whether a useful circuit can be designed by an evolutionary process.
The answer to that question is yes.
Well, it may be to you, but here we are discussing a specific circuit. Since you have a background in the subject, you might have some opinion as to the evolved circuit and how it functions. Specifically, how it functions compared to the patented circuit in the environment and uses for which it was designed.
Well, your honesty and integrity cannot be challenged.
In a million turn 10K pot.
Computers are very good at iteration given a problem, a desired solution, a dbase and a good programmer.