Artificial Life Forms Evolve Basic Memory, Strategy

Calopteryx notes a New Scientist piece on how digital organisms in a computer world called Avida replicate, mutate, and have evolved a rudimentary form of memory. Another example of evolution in a simulation lab is provided by reader Csiko: "An evolutionary algorithm was used to derive a control strategy for simulated robot soccer players. The results are interesting — after a few hundred generations, the robots learn to defend, pass, and score — amazing considering that there was no trainer in the system; the self-organizing differentiated behavior of the players emerged solely out of the evolutionary process."

Comments

Re:Not really amazing...

[Anonymous Coward]

Saying there wasn't a trainer in the system is a bit of a misunderstanding really.

Evolutionary algorithms always makes use of a fitness function to define which generations are to survive and evolve and which are to die off, this is the case in the presented setup as well. Without knowing the project i'd guess they let the "teams" play against each other and let the winners survive.

If there wasn't a fitness function it wouldn't really be an evolutionary algorithm, evolution sorta implies "survival of the fittest" and all that you know :) The interesting part is observing the emergent behavior, in other words what we were not expecting to get out of the system. When the system doesn't have any knowledge of what a "defender" is, or what "passing the ball" means, it's interesting to see these well-known patterns evolve even when they are not specified, this is what matters to the AI researcher.

Other implementations of evolutionary algorithms may be fun (http://rogeralsing.com/2008/12/07/genetic-programming-evolution-of-mona-lisa/) but are not showing emergent behavior because you are asking for a specific output through the fitness algorithm. That is the main difference.

Addendum to first article is pretty good

[somersault]

In the late 1980s, ecologist Thomas Ray, who is now at the University of Oklahoma in Norman, got wind of Core Wars and saw its potential for studying evolution. He built Tierra, a computerised world populated by self-replicating programs that could make errors as they reproduced.

When the cloned programs filled the memory space available to them, they began overwriting existing copies. Then things changed. The original program was 80 lines long, but after some time Ray saw a 79-line program appear, then a 78-line one. Gradually, to fit more copies in, the programs trimmed their own code, one line at a time. Then one emerged that was 45 lines long. It had eliminated its copy instruction, and replaced it with a shorter piece of code that allowed it to hijack the copying code of a longer program. Digital evolvers had arrived, and a virus was born.

Avida is Tierra's rightful successor. Its environment can be made far more complex, it allows for more flexibility and more analysis, and - crucially - its organisms can't use each other's code. That makes them more life-like than the inhabitants of Tierra.

Actually, organisms using each others code sounds way more like our world than ones that can't leech off each other. They already pointed out viruses, and plenty of species exist today that need other species to continue to survive.. in fact pretty much all animals need to eat other lifeforms because we can't draw energy from the sun directly.

Re:Addendum to first article is pretty good

[Dunbal]

Organisms can perfectly draw energy directly from the sun, and animals and humans still do (such as vitamin D production).

      As a physician I find your statement ludicrous. While there is a photochemical step in the synthesis of vitamin D it's hardly fair calling a double bond being split by a photon as "drawing energy" from the sun. For that matter you could say that the dimerization of thymine in DNA by sunlight (which produces the genetic damage observed when a person is exposed to UV radiation) is another way we "draw energy" from the sun.

      Humans do not produce ATP from sunlight. Period.

      And I would agree with OP - all organisms, including plants, are directly dependent on other organisms. Without nitrogen fixing bacteria to fix nitrogen for the plants, and without decomposing bacteria to release minerals again into the soil, even plants would not exist. While the organisms that are set up to harvest sunlight directly from photosynthesis are the biggest input into the food chain, they can't live without the rest of it, especially the lowly decomposers. We're now all totally dependent on one another.

Re:Not really amazing...

[OeLeWaPpErKe]

The fun thing is that these robots truly have a one-track mind. They do not learn -at all- within one generation, even if they have a brain that is relatively similar to ours. The brain is configured -entirely- at "birth" by the natural selection algorithm.

And yet they display a few remarkably human traits, that seem to -but don't- indicate learning. Memory. Strategy. Having a strategy responding to the "enemy". Yet by most standards -they don't think during the game. This makes one wonder ... is the fact that humans have memory, adapt "somewhat", devise strategy really an indication of the level of thought we think humans have ?

Makes one wonder just how one-track the human mind is. Everyone likes to always accuse everyone else of "not seeing the truth" about very nontrivial problems. Are people really "seeing the truth" or just repeating what they were programmed ?

History of science definitely seems to agree with the "programmed" argument. Other histories ... even more. We are mindless automatons, we just like to think we aren't.

Tierra was - and is - really cool.

[Dr. Manhattan]

In the late 1980s, ecologist Thomas Ray, who is now at the University of Oklahoma in Norman, got wind of Core Wars and saw its potential for studying evolution. He built Tierra, a computerised world populated by self-replicating programs that could make errors as they reproduced.

I was so amazed by the results claimed for Tierra that I went and reimplemented it myself. And damned if I didn't get similar results. At the time, it blew me away that such a system could come up with novel solutions I hadn't expected or 'programmed in'. Indeed, a couple times it took me a while to even figure out how the things worked.

Re:Intelligent Design tag?

[mdda]

Actually no. The evolution mechanism is really robust.

Basically, if you have a bunch of random individuals, and the 'evolution' just mashes a bunch of the better ones together, you'll see the increase in fitness occurring. But it's not just a small effect : almost any crazy 'mashing together' method works, and the adaptation will spark off unbelievably quickly.

I know this because I did this for my PhD back in 1995. I had a choice then between going the Neural Net path, and playing around with the Genetic Algorithm/Genetic Programming stuff. Simple experiments proved that making NNs 'do the right thing' was a fairly tricky process of getting things set up right (and your formulae had to be right, etc : a fairly sensitive procedure). But the Genetic stuff was amazingly robust : almost any crazy method of crushing individuals together will produce remarkable innovation and learning (on a population basis).

But don't take my word for it, write a small piece of code yourself. The literature makes it sound like a more exact science that it needs to be. As I said, almost any 'mashup' method will work - the 'evolution thing' will simply find a way to 'protect' the important stuff.

So while this looks like 'old news' in some ways, I'm glad that they've got an eye-opening application : More people should know how much the computer guys can add to the biological evolution debate.

Re:Intelligent Design tag?

[sco08y]

I would tag this as "more proof soccer sucks." Really, soccer aficionados claim they see all these advanced movements, and that someone really does play better.

But, let's face it, they don't. They're just a bunch of people running around randomly, and occasionally someone scores by pure chance. That's why the games are always 0-0.

Seeing good soccer in random movement is part of the faith, much like astrologers see divine constellations in the random pattern of stars in the night.