And they are very different and may well have different answers.
1:Is it there? Since we know it exist one place in the universe a "no" answer seems strange (giving earth a special and unique place?)A rather weak assumption.
The second question could be:" Is all life rather "similar"(of course there may be difficulties defining basic "similatity" versus "difference" since it would be rather absurd to believe all worlds are exact copies of earth. How "similar"? Still I think most of us could imagine both a world we would agree is "basically earthlike" and one that is not.)?
None of the possible answers to the second question(basically yes or no) says anything about earth being "unique", but are different views about the nature (or perhaps laws) of life and the universe. So it may be (or not)it is all very much like at earth.

Degrees of similarity:

1. DNA/proteins

2. Some other organic molecules, but still carbon/water

3. Different basic elements and/or solvents, but still chemistry

4. Not chemistry-based at all -- magnetic structures inside stars, or something like that (if they exist in or even on Sun right now, we could be looking right at one and never guess it is alive)

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Fiction has to be plausible. Reality is under no such constraint.

ARE there ARE two questions. Not IS.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

I like No 4! won't go sunbathing nude again you never know who is watching!

I don't have a copy of it at the moment, but sci-fi writer Isaac Asimov (who was also a professor of biochemistry ) wrote an essay in the '60s or '70s where he took every planet in the solar system and suggested a unique but possibly viable chemistry that might work in each of the differing environments.

You might want to look it up....

Intelligent life is as likely to have red (iron) blood, two hands with five fingers each as it is to have legs like a crab and it's blood be based on copper.

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I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Mine: "Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that."

Heinlein's: "Staying young requires the unceasing cultivation of the ability to unlearn old falsehoods." "Freedom begins when you tell Ms. Grundy to go fly a kite."

I would like to say not.

Perhaps not. At a sufficiently high level of categorization evolution will have generated many "body plans" for the biota in each of the compatible environments. Those with DNA structures, iron blood transportation, two manipulators, and two locomotors will have competitive advantages (optimal "brain" loading) in the march to technical competence and result in not being significantly different from us.

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For those inclined to oppose human meddling with the structure of the universe or the composition and configuration of objects and groups of objects within the universe, consider:
Whether there is a limit to the magnitude of a modulation of chaos below which order remains invariant? Or, is order but a fiction invented by perspectives applied over finite, however large, time intervals?

Perhaps your definition of 'not significantly different' is significantly different to mine. I would suggest that since all categories of life on this planet are endemic to our planet, that is to say, not found anywhere else, we will certainly be significantly different to life elsewhere.

To put it explicitly; there are no, and there will never be, any members of the kingdom Animalia anywhere else in the universe unless they travel from Earth in some way.
There are not, and there will never be, any members of the phylum Chordata anywhere else in the universe unless they travel from Earth in some way.
there are not, and there will never be, any members of the class Mammalia anywhere else in the universe unless they travel from Earth in some way.
there are not, and there will never be, any members of the order Primates anywhere else in the universe unless they travel from Earth in some way.
there are not, and there will never be, any members of the species Homo sapiens anywhere else in the universe unless they travel from Earth in some way.

There may be animal-like, vertebrate-like, mammal-like, and human-like (or humanoid) species out there, but in my opinion they get increasingly unlikely as the level of complexity increases.

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Orion's Arm . The Starlark . Voices: Future Tense . OA Flickr set

Is there any way we can confirm, at this point, that the life on Earth is not also found elsewhere?

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"You miss 100% of the shots you don't take" - Wayne Gretzky

Technically, we could never, ever, ever "confirm" that...

So we'd best not make absolute statements like "there are not, and there will never be, any members of the species Homo sapiens anywhere else in the universe unless they travel from Earth in some way," then.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

Oh I think the probability of Earth related life existing elsewhere without either coming from Earth or being the origin (don't ask me how) of the life here is really very small indeed (and that's very, very small).

And if the direction of travel is from there to here, then the life that gets transferred (and manages to become our extensive biosphere) is not going to to be even eukaryotic.

I agree with Aginglb on this one too.

I will make absolute statements like that.

Because Although I could never confirm beyond all shadow of a doubt... That actual likelihood of it is so insignificant that to entertain the notion would be irrational.

I'm just saying maybe we should wait until we've actually visited a few other worlds before we decide what can and can't be there.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

Why?
We can make a lot of observations and base our educated guesses on a already existing knowledge.

I don't need to dip my toe in a pool of water to know water is wet.

I don't need to pick up a rock and squeeze it to see if it his hard.

In which case they are merely educated guesses.
And we have the problem that we have very little data on what conditions are like on other worlds, so making sweeping statements of what can and can't be there is just vague guesswork until we actually go and look.

I'm not saying there are worlds full of life identical to what we find on Earth out there, merely that we don't know either way at this point. It seems extremely unlikely to us that we could meet other humans out there, but we are working from very little information of what out there is like.

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"You miss 100% of the shots you don't take" - Wayne Gretzky

You quoted me without including reference.

That's considered impolite. Please don't let that happen again, either with me, or anyone else. Please use the quote button so that the poster to which you're referring is including in your response.

Thank you.

It's just proper netiquitte.

Here's the post:

And my reply:

I do tend agree with your iron oxygen system, bipedal locomotion as well as bipedal manipulation, which makes as much sense on land as it doesn't make any sense in the water, hence the reason whales, dolphins, sharks, and fish have flippers, not hands.

Yet we find several variations throughout nature, each optimizing on variations. Primates can walk, humans are the best, we can climb trees, some of us are prehensile; ants are six-legged, some with pincers, some with stingers; termites also six legged, but many with various other mechanisms.

Arachnids, the eight-legged variety.

Worms. No legs at all, just like snakes and two varieties of lizards, yet they seem to do just fine.

Birds.

Fish.

What I'm getting at is that there are many niches within the evolutionary cycles because there are many environmental conditions. Cold, hot, dry, wet, land, sea, windy, etc.

The reason that we're at the top of the food chain is because we're not really tied to any particular environment, including the vacuum of space. We've "been there, done that." Even though, technically, we weren't the first off the planet.

However, we sent those who were, and not because we thought they were better than us, but because we thought they were expendable, and we weren't.

So...

My point is that we live on a planet with a highly varied climate. It's only natural that the top of the species would originate from the species that can live in -100 to +130 temps, no lack of fresh or salt water, and with a food supply chain 24,000 miles long.

What other species on the planet can boast this?

My point is that we don't occupy a "nich."

We occupy something called "domination."

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I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Mine: "Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that."

Heinlein's: "Staying young requires the unceasing cultivation of the ability to unlearn old falsehoods." "Freedom begins when you tell Ms. Grundy to go fly a kite."

The existence of extra-terrestrial but separately evolving humans would suppose at least carbon chemistry (which we do know is amazingly diverse), that's a start; then polypeptides, fair enough, amino acids exist in space; but then the DNA/RNA with its encoding, is that unique? Is even the genetic code unique or arbitrary; then the particular "implementation" of the protein based form of life. I'd say that rather considerable improbabilities mount up.

I could go on. For goodness sake, I and others have been battered to the point of abuse for even entertaining the idea that extra-terrestrial life is not incomparably different, now we are told that we cannot rule out convergent evolution on an "astronomically" improbable scale.

I do not think it unreasonable to point out that, although there may or may not be roughly analogous biospheres, we already have enough information to suggest that it is extremely improbable that they would be fully cognate with our our own chemistry, let alone our actual phyla.

And if there were, I would say that we might make some quite astonishing deductions from that possibility.

Of course, the existence of life in the first place is highly improbable.

So rather than all this guesswork, lets get those FTL drives designed and built so we can go find out.

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"You miss 100% of the shots you don't take" - Wayne Gretzky