system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we assume that "intelligent life" on other planets needs oxygen?

I guess looking for oxygen on other planets makes sense for our use...but why do so many papers assume oxygen = alien life?
gpt
Just about every living thing on this planet requires oxygen and is carbon based.

While we can guess at other types of life forms that are based on, say, silicon, etc - and may use, say, methane - we don't have any proof that these exist.

It is easiest to look for what we are familiar with.  If it exists here, it probably exists elsewhere.

On the other hand, we would have no real way of knowing what a methane based life form would exhibit - that we could easily test for at a distance (e.g., looking at a planets spectrum, for example).