Effects of different atmosphere on evolution

[drcathyc]

I am a science fiction writer and I need some help with developing a plausible alien species. The species has to end up technologically advanced. What would be the effect on a species that evolved on a world with 74% nitrogen and 25% oxygen (other gases remaining similar to Earth)? Thanks for your help.

 

[Mattara]

You can't predict how or if evolution is going to take place if you only take into account the atmosphere. You need to look on many other elements. If you only consider that atmosphere, you will end up with nothing.

 

[iansmith]

From the perspective that life on this planet started in atmosphere that did not have oxygen, we can only speculated how the appearance oxygen transformed life.

Oxygen create a lot of damage in part by reacting with iron to form radical. Bacteria evolved mechanisms that quenches iron, so it is less likely to react with oxygen and very few bacteria have evolved so they use some other metal, such as Mg and Mn, than iron.

Life that evolve with a greater oxygen may not be that differrent than what you see on Earth but it could also have evolved mechanisms that renders it more resistant to oxygen damage or that oxygen does not do any damages.