[Space] Interactions between species

[johndallman]

Originally Posted by Frost

. . . sapient life (with similar biochemistry) is relatively common.

There are several meaningful grades of "similar biochemistry":

1. We can breathe the same air. This might not be identical to anyone's home atmosphere, but it's compatible with the species of interest.
2. Same air, same water (nobody requires strange additives in the water).
3. Same air, water, and some of the same foods.
4. Same air, water and food, with nutritional supplements. Quite a lot of space opera can fit this, if you assume characters take their vitamin pills off-camera.
5. We're from essentially identical biospheres.