Ok, now this: why do multicellular organisms (us, for example) live in groups?

Is it that we need to share microbes or we'll die? We know we need to have a healthy gut populated by a vast ecosystem of microbes - but how do we acquire them? (We get them from one another, although fully how is still not known.)

If we (or mice or cockroaches) lived in isolation, how would we acquire our necessary flora?

So who is cultivating whom?

Here's what's super fun about having science be my job. I can be pondering and then be like, "ok, so then how would I test this thing?" and 99x out of 100 it doesn't work. But every once in awhile things behave the way you guessed.

These are tubes of bacterial growth media. One has bacteria, one doesn't. They start out blue, if the oxygen gets used up, it turns pink. We knew this bacteria used a lot of oxygen but I was not expecting it to suck it down this fast.

Trying to get smarter about how oxygen is toxic to anaerobic organisms but the cool perspective shift I got smacked with right away is:

Oxygen is a super dangerous and damaging element and its actually those of us who live in it that are weird: we have all developed extensive tools (enzymes mostly) to ensure oxygen isn't tearing us to pieces.

Some organisms don't have these (in particular superoxide dismutase) so oxygen kills them.

They aren't weird, we are.