Now, I know you are not all necessarily believers in the idea of evolution, or spontaneous evolution. This discussion has no place for debate on the veracity of Darwin's claims, nor of the existence or lack thereof of deities. This discussion requires the acceptance of presumptions, and the logical expounding of those presumptions.
This discussion will take the following assumptions as true for the sake of discussion. Anyone who wishes to refute these points, must take their discussions elsewhere. Anyone trying to turn this into a debate of religion or science outside of the suggested points, will be asked to leave the discussion, and I request that any administrator reading such flame-bait remove it.
For the same of game design theory, we are going to assume that the entire universe was created by a scientific process, and that a "designer" will have some interaction with certain bits of this process. So in actuality, this discussion will actually involve "guided evolution".
Facts for discussion:
1) The origins of life are spontaneous.
2) All life begins at a single-celled phase.
3) All life is made of carbon, and depends upon water as a medium.
4) All life breathes some sort of gas, either carbon dioxide, or oxygen.
Stages of progression:
For the sake of this discussion, we will assume that life must cross several hurdles to reach the end goal. In this discussion, the end goal of life, is to populate their galaxy.
These hurdles should include:
1) Spontaneous generation of single-celled life.
2) Progression to multi-celled life.
3) Advancement to a complex creature.
4) Ability to walk and live on land.
5) The ability to operate tools.
6) The ability to communicate complex ideas with fellow members of the species.
7) Harnessing of metal, or a metal-like substance.
8) Understanding of physics, chemistry, etc.
9) Development of spacecraft
10) Faster than light-speed travel
These are the immediate goals I can understand being necessary to progress as a species.
There are four phases to progression, development of the body, the brain, technology, and society.
I also would like to explore my reasoning for a few things:
1) Landwalking creatures may only become sentient enough to leave the planet. This is due to the fact that space exploration requires metal. Metal and carbons are only malleable in extreme temperatures, and as such, must be forged on land, as water would transfer the heat, and boil the creature attempting to mold the material.
2) Society must cooperate to become a space-faring empire. Warlike creatures would have to maintain control of their planets, and would expand slower than creatures of a hive-mind, or of a natural disposition to peace. However, aggressive creatures would naturally expand more aggressively, and be more adept at conquering. Peaceful creatures would work more slowly, but would not be distracted by insurrection and lack of strong infrastructure.
I would like to discuss alternate methods of evolution for creatures, and different advantageous or disadvantageous traits and forms for the progression of a species.