[RC5] Re:Tierra

Matt.Wilkie Matt.Wilkie at gov.yk.ca
Fri Jun 18 10:18:34 EDT 1999

>OK, what exatly does Tierra do? It's interesting, but I don't 
>know what it's purpose is. Maybe it's like, some thing that goes 
>around "infecting" computers with parasites? Then the parasites 
>grow, learn, and evolve into some sort of intelligence? I mean, I 
>don't get this. Culd someone please explain to me what is IS I 
>mean, I just don't get it.

Tierra is a system for researching and experimenting with artificial
(digital) life. Tierra, the "world", is a virtual computer with it's own 
Darwinian operating system. Tierran "organisms" are small  (20 to 
100 bytes) collections of the Tierran machine code which contain
simple instructions to replicate themselves; "be fruitful and multiply".
In this respect they are similar in behaviour to computer viruses. 

A Tierran denizen cannot survive outside of Tierra. It's be like you 
trying to breath in space. The Tierran virtual computer's OS does not 
share any commands with real computers. Ergo a Tierran could not
"infect" a real computer.

Tierra goes beyond virus-like activity by introducting random bit-
flipping throughout the memory space which has the effect of
mutating the Tierrans as the reproduce. This is where the evolution
aspect comes into play. There are eveolutionary pressures as well
but I won't get into that here.

The interesting thing about watching the Tierrans evolve (which means
they reprogram themselves) is that they come up with novel approaches
which the experimenters haven't thought of. One example is where
one of the species managed to compress it's operating code from the
original 80 bytes down to 42 (or something, I forget) and still accomplish
it's deeds (replicating). One of the theoritical real world implications of
is that the Tierra  system could be used for optimising human-created 
programming code.

Oh yeah, one more thing, the Tierran critters thus far produced are best
compared to single celled protozoa and bacteria. Still pretty low on the
evolutionary scale.


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