Thanks for the comments
it's been a while since I posted this! I let go of this evolution project because it was always crashing..
If anyone's curious, the idea (the first step, at least) was to make every point of the sphere oscilates (with a physical force), each with it's own set of parameters, like frequency and such. Every parameter would be randonmly generated only once. Then the physics engine would just let the ball move randomly by itself.
The interesting part: This would be done, say, ten times. Each with a new set of randomly generated parameters. Then the 'experiment' would be repeated (ten more balls) but the random parameters would be biased towards the balls that moved farther, in the previous experiment. This, I belive, would select the balls that actually move on the ground in some direction, and we would eventually see balls that could move itself. All generated by randomness! (of course, I don't have a clue about the number of times this had to be repeated in order to see something meaningful)
Btw, I can't see this thread in the forum for some reason o_O