Probably a bit yeah. But there is an argument that it is hard to store a lot of chemical energy without abundant oxygen in the environment. Oxygen stores a ton of energy, and it's quite difficult to achieve comparable energy density without it. This is the basic reason why gasoline has so much more energy than batteries, and people are developing batteries that use oxygen from the air to increase energy density. I remember reading in a Wikipedia article that Earth's atmosphere before it became oxygenated would likely not have been able to support multicellular life with energy-intensive things like muscles and complex brains.

But without knowing if Europa has any life at all this is probably putting the cart before the horse.

Oceanic hydrothermal vents teem with anaerobic life which uses a lot of interesting chemistries instead, e.g. based on sulfur.

> Oceanic hydrothermal vents teem with anaerobic life which uses a lot of interesting chemistries instead, e.g. based on sulfur.

Yeah, but none of that anaerobic life is "multicellular life with energy-intensive things like muscles and complex brains." It's all bottom of the food chain bacteria.

Technically anaerobic multicellular life exists [1], but it definitely not comparable with aerobic forms.

[1]: https://en.m.wikipedia.org/wiki/Anaerobic_organism#Multicell...

It doesn't. There's plenty of anaerobic life on earth.

But none of it is intelligent. Anaerobic processes are drastically slower and less efficient than aerobic ones. I wonder if a functioning brain could even work anaerobically. 20% of our oxygen consumption is done by our brain.

If we find any life at all on Europa, intelligent or otherwise, it proves that earth is not the only planet with life. It’s an obvious conclusion but if we find alien life even in our own solar system that says something about the prevalence of alien life.

I never thought the expectation was intelligent life. Even the discovery of a single celled organism would be a truly remarkable moment for humanity.

Agreed. I'd love to find any living thing.

Unless we later discover it traveled there after an impact event on Earth.

I suspect that is extremely unlikely due to the amount of energy required to get from earth to so far out from the sun, but maybe.

EDIT: Here is a study of the probability of such a thing. It is indeed very low. https://www.space.com/alien-life-europa-enceladus-second-gen...

Don't worry about "intelligent", I don't think there's anaerobic multicellular life on Earth

(yes even plants use oxygen - they just happen to produce it as well)

There are some multicellular anaerobic organisms, such as a few species of Lorificfera. It is worth noting that they all appear to be descended from aerobic ancestors that lost their ability to process oxygen. Multicellularity is very difficult to evolve, and has only happened a few times.

The only intelligent life we know of is, and has energy demands within the bounds requiring oxygen powered metabolism.

Well... Nobody is expecting to find a civilization under the ocean of Europa. Microbial life is already alien life.

It’s not that it needs to be, it’s just that—based on our knowledge of the chemical elements—life based on some combination of oxygen, carbon, hydrogen, and nitrogen is by far the most likely.

Other forms are certainly possible, it’s just that they are highly highly unlikely to form and remain stable, and develop into complex intelligent life.

So all of that informs where you should focus your efforts on research and searching.