How do you think life on earth started?

A. We originated here. I.e. through the normal process of evolution or intelligent design. (Whatever is your fancy.)

B. We were “seeded “on this planet by a more advance alien race.

C. We migrated here from another star system forgetting through the millennia how and where we came from.

Any variation on these ideas are welcome...

I go with A. There is enough evidence that Humans naturally evolved from earlier life forms rather than showing up in the fossil record with no prior history.

I think Panspermia is possible, but that means Earth was seeded a few billion years ago.

I pick A, and I fancy evolution.

Humans can't have moved to Earth, because we have a clear evolutionary track that shows we originate from here.

The evidence you refer to I am assuming states that we started from basic chemicals (building blocks of life) in the early stages of earth’s development and evolved to what we are today. But what if we moved her by interstellar pollination of our DNA/RNA? What if our predecessors sent their chemical signatures out amongst the cosmos towards developing planets and some of that landed here either by accident or design? Could it be possible then we are the byproduct of such a process? Maybe this is the way our ancestors realized that interstellar travel and colonization was most viable? What are your thoughts?

If our DNA was seeded on the Earth 4 billion years ago, life on Earth would have had a much different history. As it is, it took over three billion years of mutation and selection for the DNA of four billion years ago to begin to resemble our DNA.

I might have jumped the gun by using the word "DNA" but what I am more refering to is the distinct chemical building blocks that uniquely, when introduced to a developing world billions of years ago, would evolve and mutate into our distinct physical signature.

I suppose it is possible that one branch of life, such as archaea, originated on Mars and came to Earth via panspermia.

I don't see any reason to invoke some sort of alien intelligence that seeded life here, although it does make a good SF story.

__________________
"I'm as accurate as any psychic. And I'm a cartoon!" -- Squidward

"Arrrgh, the laws of physics be a harsh mistress!" -- Bender

I would like to add that the idea of Panspermia is not that hard to believe in fact there is some evidence today that supports this process may be occurring today to some degree. Remember, interplanetary transfer of material is well documented, as evidenced by meteorites of Martian origin found on the Earth. Thomas Dehel in 2006 proposed that plasmoid magnetic fields ejected from the magnetosphere may have the ability to move life bearing spores from a Earth like planet's atmosphere with sufficient speed to cross interstellar space to other systems before the spores can be destroyed.
Our own space probes may also be a viable transport mechanism for interplanetary cross-pollination in our solar system or even beyond. So the idea that spores or building blocks from other worlds creating ours I don’t think can be so easily ruled out. (Not that this is what I believe but I feel it deserves further discussion.

I agree and I would buy the tickets to the movie. They would be a amazing species though if it did. Think of the math behind such a endeavor. The probabilities!!! Beyond our knowledge by today’s standards for sure.

A. (but drop the ID, this is a science based forum )

B: possible... No evidence against it, no evidence for it, really. Ockham's hair removal device says: scratch.

C: "We"? No. I don't really see a way to fit that into our evolutionary past, except as B.

__________________
"Ignorance more frequently begets confidence than does knowledge" -- Charles Darwin
"Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
Meet the OOONG TOE.

So our remote bacterial ancestors may have come from Mars. However if this did happen they were very primitive, and evolved into every species on Earth, not just humans. There is plenty of evidence to show that all the species on Earth are related, and came from a very primitive ancestor about four billion years ago.
But once they reach interstellar space they have to reach another star- which is a very small target indeed. On average the spores would have to travel for billions of years before encountering a star- by which time the DNA would be denatured. We've had several discussions on this possibility in the past- it seems that interstellar panspermia would have to be a very rare phenomenon, and almost certainly much less likely than abiogenesis.

The transfer of life from star to star by deliberate agency (by extraterrestrials) or even accidentally (we might have evolved from the contents of their spacecraft's septic tank) is a remote possibility. Whatever we evolved from was very primitive, and would not have any predisposition to evolve into humanity (or into elephants, frogs or oak trees, either).

__________________
New Orion's Arm Site . The Starlark . Against a Diamond Sky (OA Novella Collection) . OA Flickr set

There is no way to predict what direction evolution would take. It is too dependent on random occurances, from single cosmic ray-induced mutations to planetwide extinction events.

Although there is no evidence to support "seeding" from other planets or alien life you cannot rule it out as a possibility. The one problem being that all you can do then is move the question back a generation and then ask "well if so where did they come from/originate?"If you are to believe in evolution then it has to be that some time in the past, regardless where, that by chance a mutation occurred due to certain environment and situations that sparked biological life into action.

It could turn out that we maybe the first in the universe. You may then say well our planet is only 1 in countless billions of others and that it is only 4 billion years or so old, 9 billion years or so younger than the observable universe. Yes this is true but we are thinking about time in human terms rather than cosmological terms. If the universe turns out to last thousands of billions of years, anyone in the far distant future looking back at past data may conclude that life seemed to have originated here on Earth very close to the early beginnings of the universe, and that all life as they know it could have possibly originated from Earth. We could turn out to be the ones that seed the whole galaxy/universe.

This is not my personal view but its my point about the scale of time and the universe. There are so many wondrous possibilities that we just cannot make any defined judgement either way.

so what do we know...?

Well we it seems life began shortly after the environment was suitable for liquid water on earth. The evidence we have so far suggests that all life on earth is genetically linked, thus it seems that earth alone was the origin, no need for "seeding" as such. So the best conclusion we can make is that all life that we know appears to have originated here on earth by a chance occurring suitable environment and available compounds.

__________________
ooops..... wrong forum!!!

I agree. However, this does not rule out that our genetically related life is the result of "seed" dropping on Earth shortly after the environment was suitable for liquid water. But I think it's more likely that life started here.

Earth seems to have been in the best position of all the planets regarding its distance from the sun (in the Goldilocks zone) since the early days of the solar system. I don't see what Venus or Mars could have had that the earth didn't. And I don't see life traveling to earth from any farther than it's immediate neighbors.

I tend to think some form of panspermia is the process whereby earth-life started, given the apparent too narrow time frame available between a habitable Earth and an inhabited Earth. The earliest known life is quite complex and it seems farfetched that it achieved said complexity, through mutational accidents, in a few hundred million years.

__________________
"Where the telescope ends, the microscope begins. Which of the two has the greater view?" - Hugo

"Men occasionally stumble over the truth, but most pick themselves up and hurry off as if nothing had happened." - Churchill

I remain skeptical of this assertion; we have evidence for interstellar material transfer while we have no evidence of abiogenesis.

__________________
"Where the telescope ends, the microscope begins. Which of the two has the greater view?" - Hugo

"Men occasionally stumble over the truth, but most pick themselves up and hurry off as if nothing had happened." - Churchill

Maybe we all came from cyanide?

Was life founded on cyanide from space crashes?

As already noted, panspermia just ignores the problem - life had to have started somewhere, and almost certainly more than just one somewhere. Why not Earth? There may have been a trillion other earth-like planets on which the conditions were never just exactly right for life to emerge and evolve. We're here because we're here. This was the one in a trillion success (or failure depending on your opinion of the current dominant lifeform )

__________________
Andy

Manager Ukweatherworld

I think that inappropriately trivializes the importance of the question.

If life originated here on Earth, it becomes plausible that it was a fluke and that life is exceedingly rare (an alternate interpretation being that forming life is a simple, easy process, and life is very common). On the other hand, if life were seeded here, than it seems likely that the "seeds" are floating around all over the place out there, and life is likely to sprout wherever conditions allow.

It also has ramifications for the question "How similar and/or different to us would alien life be?"

If we were seeded, then it becomes likely that there are other worlds where life is carbon based and uses DNA. On a planet with a similar environment, "sown with the same seeds", it becomes plausible to think that evolution may very well produce life that is remarkably similar to us. Not identical, of course, but I'd bet that we'd find recognizable body types (fish, quadraped, biped). If life occurs spontaneously on each planet where it occurs, then the answer to this is much more up in the air.

Then there's the in between possibility. Life arises spontaneously relatively rarely, but in the places that it does arise, it gets scattered elsewhere. In this scenario life could be relatively common, but there could be a small number of distinct "types" of life. We could be living in the carbon based neighborhood, while a different region of the galaxy is dominated by silicon based life.

All pure speculation of course. It just seems to me that panspermia vs abiogenesis has larger ramifications than just moving the question back.

The bottom line is that we as a species don't yet know how "life" on this planet originated. We are still investigating this matter.

As both a highly-trained and experienced astrophysicist and geophysicist, even I don't know how life came to be on this planet.

We are not as smart as homo sapiens to have yet come up with the answer to this question. We are not as smart, as a species, despite how many of us would like to believe we are. The inquiry on this particular issue remains a mystery to those of us who pursue this matter, looking for an answer. And that's it in a bottle.

Eric

__________________
“Out yonder there was this huge world, which exists independently of us human beings and which stands before us like a great, eternal riddle, at least partially accessible to our inspection and thinking. The contemplation of this world beckoned like a liberation.” - Albert Einstein

My Astronomy Site
My Geology Site

Why? What do you mean with plausible? If life originated here, there is no reason to assume that it thus is exceedingly rare. Why is there reason to assume that panspermia seeds are very succesful in "sprouting life"? Perhaps ours was the only planet where it worked...

__________________
"Ignorance more frequently begets confidence than does knowledge" -- Charles Darwin
"Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
Meet the OOONG TOE.

Honestly, those are just the assumptions that make intuitive sense to me. Given the lack of hard evidence either way, discussion of the topic will, by nature, involve a good amount of speculation and intuition.

But where did the seeds come from? It seems to me that panspermia would imply that life exists in at least one other place.

Thus back to the "fluke" Not really arguing, you're right, it's speculation. Fun, though, somewhat.

__________________
"Ignorance more frequently begets confidence than does knowledge" -- Charles Darwin
"Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
Meet the OOONG TOE.

Definitely.

I think the significance of panspermia really depends on what question you're asking.

If hard evidence were found tomorrow that Earth life began through panspermia, it still doesn't do much of anything useful to answer "How did life begin?".

On the other hand, it would have very significant effects on the assumptions we make when asking "Are we alone?".

I buy into this theory the most. There are small to a medium number of distinct forms of life (Remembering the Universe is massive) and that seeding within close star systems is possible for those types.

Well ours and the origin planet the panspermia seeds came from

Then that leads to my original poll question(s) on this post. If you believe it was panspermia, do you believe that it was just chance pollination or by advanced design from a race well beyond our own science, technology and mathematics to currently comprehend. Earlier, there were some that dismissed this theory so quickly and I wonder if it’s due to ego or science? I hope we are not so proud as a race that we can't accept the fact that we could be a very young species compared to other sentient life in the universe (If such life exists) and that such calculations of random events (such as evolution and the events that shaped our world/being) are not possible. Calculations I would assume would be critical when picking a planet to pollinate with one’s chemical signatures. Think of the predictions and the probabilities that we are able to accomplish in just the last 60-80 years of our technological advancements. (Such as weather tracking predictions etc...) Imagine a race that has been analyzing causality and probability for the last 1,000 or even 10,000 years?

Part of it was that your original post was confusing. Many of the initial responses assumed that when you said "we" you meant humans. Later, some of us started discussing bacteria and suchlike.

If you did mean humans in the original post,then yes, dismissing it is entirely due to science.

__________________
"I'm as accurate as any psychic. And I'm a cartoon!" -- Squidward

"Arrrgh, the laws of physics be a harsh mistress!" -- Bender

Sorry Aurora if I was unclear. I am talking about option B in my original post and that the aliens used seeding to place us here. They dont have to be humans.

That's not what aurora meant. The problem is that your OP implies that the seeding party (aliens) put humans ("we") on Earth, rather than just the start of life in general. You're doing it again in this post: "used seeding to place us here". If you mean "us" as us humans, then the idea is hard to reconcile with known evolution. If you mean "us" as the first sparks of life, then it's possible.

__________________
"Ignorance more frequently begets confidence than does knowledge" -- Charles Darwin
"Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
Meet the OOONG TOE.