The discussion centers on developing a plausible alien species that evolved in an atmosphere composed of 74% nitrogen and 25% oxygen. It emphasizes that while atmospheric composition is crucial, it is not the sole factor influencing evolution; other environmental elements must also be considered. The conversation highlights that life on Earth initially developed in an oxygen-poor atmosphere, suggesting that the introduction of oxygen significantly transformed biological processes. It notes that oxygen can be harmful due to its reactive nature, particularly with iron, leading to the evolution of bacteria that have developed mechanisms to mitigate this damage. Consequently, an alien species in a high-oxygen environment might either evolve similarly to Earth life or develop unique adaptations to resist oxygen's harmful effects.
