Artificial Life and Competition

I’ve always been kind of interested in Core Wars. (See also the main Core Wars page, and the King Of The Hill page.) Not enough to actually compete, you understand, but enough to run a local server and let some of the more “famous” programs battle it out, and maybe to throw in one or two of my own. I am a huge geek, let it not be doubted.

Which is probably why I started reading the “Core Wars” section of the larger Get A-Life feature on SecularWeb. However, that section leads directly into the extremely interesting section on Tierra:

Ray decided to start his Tierra system off with a population of the most simple programs possible. He wrote a piece of code that simply copied itself elsewhere in memory then spawned the copy. It was 80 bytes long, so he named it 80. He spread a few 80s through the Tierra system’s memory, and started the clock.

For the first few thousand generations, nothing much of interest happened. There were a few minor mutations that didn’t break the code, but that was about it. Before long, though, there were a number of 81s–mutants with an extra byte of program code. A little later, a 79 appeared. Because the 79 had one less byte of code, it took less time to reproduce, and was more successful than the 80 or 81. It began to take over the Tierra ecosystem.

Next, something astonishing happened. A 45 appeared. Ray was initially mystified; he’d written the simplest code he could imagine and it was 80 bytes. A 79 seemed reasonable, but how could a 45 reproduce in only just over half the space? Examining the code of 45 provided the answer–and a new surprise. The 45 was a parasite: instead of reproducing itself, it hunted for the reproductive code of an 80, then called that code. It was almost like a biological virus, which reproduces by inserting its DNA into a host cell and using the cell’s reproductive apparatus to build more viruses.

There’s even more, perhaps even more interesting.

So, now I know I’m going to lose a lot of productive time over the next couple of weeks messing around with Tierra. And, I have a whole new anecdote for arguments about evolution through random changes, which is cool all on its own.