Is there any proof of life having developed in more than one instance on Earth?

I’m afraid not.

“One isn’t such a lonely number. All life on Earth shares a single common ancestor, a new statistical analysis confirms. A universal common ancestor is at least 102,860 times more probable than having multiple ancestors, Theobald calculates.”

Science News

There will be in 2–5 years. According to what I’ve heard from George Church and Craig Venter both of which have labs engineering cells from near-scratch. In terms of creating life a new.

But in terms of observing life being created anew, I don’t think we’ve seen it yet. But the places you’ve mentioned seem to have the required elements.

Yeah this breaks the golden rule of biochem, and unlocks a whole bunch of possibilities for alternative chemical life systems.

IF life developed on earth the proof is long gone. Because we’re talking about fucking molecules that had to evolve for a really really long time in order not to die. The first life, in it’s undapted form, died out a couple of weeks after it first came into existance. Because it sucked. And single molecules don’t really fossilize.

The same goes when talking about two species evolving side by side. And no proof means anything could have happened. We might have evolved from the parasites in the comet-shit of space-whales.

I think this finding coupled with the concept of Abiogenesis coupled with a billion years of earth being pelted by meteors from who knows where gives rise to the distinct possibility one or more life forms is quite possibly extraterrestrial. If a form of DNA can survive and thrive in near volcanic even highly acidic conditions, alien DNA hitching a ride on a meteor falling to earth is a distinct possibility! Fun stuff for sure.

@Zyx, not trying to start a evolution debate here, but they have more understanding of what happened than ‘none’. We can use a whole range of methods to get a fairly accurate depiction of what probably occurred.

@bluemukaki “Probably” is easy, obvious, and not what I was talking about. Of course our DNA can be traced back to a couple of amino acids that started off everything but we’ll never really know, so why wonder?

One things I do think it, as well as all the life on Earth, tells us, is that our imaginations just aren’t big enough to imagine all possible, let alone existing, life forms. This isn’t the first discovery of life ‘breaking’ the rules we wrote for it (although it’s probably one of the biggest to date)just think of all the deep sea creatures, it’s a different world there, too, where life isn’t supposed to be able to exist.—But that’s a little different, since those are clearly related to other ‘normal’ sea creatures, whereas this bacteria doesn’t.

The arsenic-backboned DNA really excites me, but I’m not sure that it alone convinces me there has been other instances of life. Although it does help support the concept, that’s for sure. Because it’s still DNA in every other aspect. But that’s just me having a hard time believing that even DNA, the way it’s created here, is necessary for life. I think that if there was a completely separate instance of life, it would be completely different. That here, Earth, the DNA form just turned out to work really well.

What it does show is that life really doesn’t have rules. We try to look at our world and go, “okay, well we’re all similar in this way, this way, this way, so those must be necessary for life!” It shows we really have no idea what makes life, so we can’t dismiss possiblities simply because they’re not the same as what we came from. We can’t even really think of the possibilities. And we can’t expect to find other life out there if all we’re looking for is our specific check list of requirements.

What does convince me of other instances, though, is of how well life has thrived here. I don’t buy the idea that it was one lucky combination of molecules never before seen, and poof! life! I think all you really need is a place where molecules can react and combine with each other, and then time. (By human standards, a very long time. Universe standards, not so much.) What’s to say the evolutionary process only started when life did? All you need is a bunch of options, and some that work, or work better than others. Actually, what’s to say evolution even works, (exactly) as it has for us, anywhere else?

Basically, I don’t think life is luck so much as a matter of time. And maybe that’s just because I don’t see how I could’ve gotten so damn lucky? I just don’t see it being so rare it can only happen one specific way that just happened to be what happened on Earth. So I don’t really need hard, cold, evidence. I don’t see it being probable at all that we’re it, or we’re the only way.

Just look at all the different forms the DNA/cell model took. We’ve got from bacteria to extremely complex multicellular organisms, and every different ‘category’ of life has thousands, millions, of very distinctly different types, here on Earth alone.
Then we have viruses, which we can’t quite decide where to put, but they have the DNA, just use it differently.
And we’ve got the mitochondria inside our cells, which look like a completely different form of cell from the one housing it. Multi-celled organisms, at the cellular level, are two different, cooperating, forms of life.

I don’t find it surprising at all that now that we’ve decided we think the base of all life is the ingredients of DNA (which I knew all the names of at one point), the phosphate-group backbone gets replaced with arsenic, one of the most deadly natural life-as-we-know-it poisons.

I guess what I’m trying to say is, no, I don’t have proof, either. But I’d be, actually, more surprised if it didn’t happen in more than one way or instance.

@DancingMind “One things”

I can’t read what you wrote now, because you made that one mistake, that one horribly impossible mistake.

@Zyx No!! Did I really??

…

Yep. And too late to fix. Gah.
After checking for typos… I miss an extra s on the second word. -_ -

@DancingMind Details….details! I appreciated your thoughts on this but will say I think our imaginations are big enough and only have been whetted by this announcement of new DNA. The possibilities of life elsewhere in this universe are now infinitely more possible and we have proof! It is terrestrial proof but it is outside the box life that no one…even Bradbury or Hawkins could have suggested other than as an alien life form. This is IMO Huge!

@DancingMind Ah, nevermind if it’s too late to edit. I read it anyway.It’s basically what I was trying to say: you can’t know for sure but the universe seems pretty damn infinite. (which means the chances of stuff not happening approaches 0)

I’ll be impressed once they find life without DNA.

@Zyx – Two words…Sarah…Palin.

After reading through the excellent link that @marinelife posted, I suspect that this bacterium will turn out to have DNA shared with the common ancestor but that it somehow found a way to swap arsenic for phosphorous in order to exploit a new habitat free from predators. If the linked study is correct, all life on Earth almost certainly shares a single ancestor. If that’s the case, then life only developed once here, or got here only once via a comet, as. @Cruiser notes. Of course, speculating that DNA arrived here in a comet just begs the question of how it developed somewhere else, and came to be in the comet rather than its place of origin.

@phoebusg I was interested here in naturally occurring life. I have to wonder if creating new strands of designer DNA and life from it is wise.

@Zyx I think the link that @marinelife posted shows that we know quite a bit more than than nothing about whether all life is related or not. From the link, “A model that had a single common ancestor and allowed for some gene swapping among species was even better than a simple tree of life. Such a scenario is 10^3,489 times more probable than the best multi-ancestor model, Theobald found. That’s a 1 with 3,489 zeros after it.”

Note that the first life was certainly a single-celled organism of very simple form. One-celled animals do not die. The prokaryotes reproduce by cell fission or budding. Current evidence says sexual reporduction is just a flash in the pan of geologic time. The Earth is over 4 billion years old, and sexual reproduction only goes back 565 million years.

@DancingMind Everywhere we look in the Universe, we get the message that reality is weirder than our wildest science fiction, don’t we? Despite its amazing adaptability once going, it is looking ever more like we all share one ancestor. If that’s true, then perhaps life forming isn’t such an inevitable thing, even on a “hospitable” class M planet like Earth.

@Cruiser There is no question but that it expands the horizons of the search for extraterrestrial life.

@ETpro I’m sorry, I’m going to say more stuff.

Statistical analasys is great for probability and stuff but why should I care about the odds. I’m reminded of Ace Of Spades by Motorhead, though that isn’t really relevant. We know nothing, though we may suspect a lot. It would be really convenient if everyone learned the difference.

Socrates>Descartes