Life's creation conundrum

[CharonY]

Skeptic, you are proving my point. Their existence had an effect on local cycles.

However, I am talking more globally. If something that is totally different in metabolism from any known biological entity exists in any significant amount, it should have a profound impact on biogeochemical cycles. Yet there is no evidence of it. Is it possible that in some remote place a very limited amount of alternative life do exist? Well, I cannot deny that. But if we limit the conditions that much to that we are slowly degrading towards the invisible unicorn argument. Of course there may be something in the ocean. However even from deep-sea studies so far no evidence have been provided. Granted, there were some mysteries, including e.g. anaerobic oxidation of methane. Yet eventually the consortium responsible for it was found.

[Aitor]

Actually we don't know if other life forms share our planet with us. it's pretty obvious that complex life can all be traced to a common ancestor but something very few people know is that when we search for life forms on the earth as in bacteria we only search for life like us. The tests we use cannot detect life that is not like us.

 

http://discovermagazine.com/2007/jul/aliens-among-us

 

 

Moontanman, you're a genius! Your link yields the perfect article for this blog. I feel I have asked a very sensible question, worthy of investigation.

 

CharonY, I admit that I know not of a place on Earth where bacteria or similar unicellular organisms do not live. I guess the "we ate all the barbarians" assertion might be true!

[insane_alien]

this isn't a blog aitor,

[Mr Skeptic]

Skeptic, you are proving my point. Their existence had an effect on local cycles.

 

No, they killed fish. In a researcher's tank. That's more than just metabolic activity, and extremely noticeable. Once they knew it was there, they looked for it until they found it. If instead it simply metabolized a portion of the fish's waste products, with known bacteria responsible for most of that metabolism, it is quite likely they would be unknown today.

[CharonY]

Still the same argument. If something is there in a significant amount it should do something noticeable. The current argument is that there should be something that we look for that is not visible to the naked eye nor easily detectable with other optical or microscopical techniques, either does not contribute to metabolic cycling or only does it to an inconspicuous amount, is only present in areas that are hard or impossible for us to reach.

The point is not that we did not find a specific species as in your example, but we have no evidence of a single organism like that.

[Moontanman]

CharonY, I see your point but I think you are assuming we are looking a lot harder than we really are. You assume all metabolic products are products of existing metabolisms, seen or unseen, or that strange metabolisms would produce some odd chemicals we don't see. There is no reason that radically different organisms have to be obvious to our tests. As far as i know all we test for is DNA, there is no way to look at a microbe, naked eye or microscope, and know if it is DNA life. I see no way to tell if there is life other than DNA life on the earth below the level of complex life, no reason to think it might not be part of the ecosystem to the extent it's metabolic by products are considered natural or part of the whole we do see. .

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The point is not that we did not find a specific species as in your example, but we have no evidence of a single organism like that.

 

No the point is we don't have any way to know if there is one or an entire complex of organisms like that. No way to know, absence of evidence is not evidence of absence.

[CharonY]

You seem to be under the assumption (as Davies is) that all biologists are looking for DNA. That is not so. In fact this is just a relatively recent technique. An organism, regarding whether it does possess DNA or not should do something measurable. However, each and every organism we were able to identify does possess DNA. If they are a significant number of alternative lifeforms around, we should be able to see even one single example of it by now.

 

If we assume they are present and even plentiful, but we are just no able to see them, well what is the difference to the invisible unicorn, or Nessy?

[Mr Skeptic]

Back in the day, would not the same have been true of radio waves? What do you mean, waves all over the place and passing through me and I can't see them cause they're the wrong color? Crazy talk!

 

All I am saying is that we can't discount the possibility of life different from our own going unnoticed right under our very noses. Let me ask you this: since the advent of DNA profiling of materials (ie, mechanically rupturing cells, doing PCR, and examining the DNA), how many more bacteria have we found that would likely have gone unnoticed but for that one technique? It's not like these guys were announcing their presence before that, and this technique depends on the knowledge we have of their internal structures.

[Aitor]

Let us look at the problem another way.

 

For a different life form to exist without us being able to realise it is there, what should it be like and not like?

 

So far, we saw that it should have no measurable effect on our environment so we don't notice. It is has a measurable effect on the environment, it exists where nobody looks. And whatever it does, it must be small and probably in small numbers to evade detection, unless it consists of things that we do not see as life (rock? gaseous substance? etc?).

 

Also, it should not be DNA based, as this is the criterion that defines our life type. So how else could it pass on its legacy of adaptations?

 

Finally, which different internal structure could its cells have, assuming it has cells, so that scientists don't know what to make of it to test for genetic material?

[CharonY]

Let me ask you this: since the advent of DNA profiling of materials (ie, mechanically rupturing cells, doing PCR, and examining the DNA), how many more bacteria have we found that would likely have gone unnoticed but for that one technique?

 

You got it backwards. Microbiology was always about combining functions with bacterial communities instead of collecting more sequences (this is a new thing, starting roughly a decade ago). While it is true that we get a higher resolution of the community, it was always the case that metabolism had precedence. You are thinking in terms of finding bugs akin to going into the woods and trying to find a new rodent/insect whatever. But on that scale the reverse is true. For instance, there is evidence for methanogenesis in rice paddy. So they start looking for bugs that could be responsible. They do not randomly fish sequences and leave it at that. You will note that bacterial species are usually defined by purified isolates rather than the existence of mere sequences. So merely based on 16s sequences roughly zero new bacterial species have been identified.

[The Bear's Key]

Evidence suggests that life appeared very soon after the Earth formed. Right. This means that life can form easily. OK so far. But

if life formed so easily, why has it appeared only once in Earth's history?

Great question. If the mechanism for life to newly begin was around once, has that mechanism simply vanished?

 

It could just either be spawning new life all the time -- in one's closet or pantry, under your sneaker, in an old pond, under someone's tongue -- or it could be spawning new life (or attempting to) periodically every few hundred thousand years. Depends on the mathematical chances of the event involving such a mechanism.

 

Could also be that life on Earth is predisposed to form DNA/RNA by the interaction of its physical conditions. If so -- and if the mechanism is time dependent -- the only way to test for it might be with a lab devoid of current life, with possibly a high degree of luck for getting the mechanism to repeat a spawn new life in there.

[mooeypoo]

Think of this question:

 

"If it's so easy to throw a ball straight into the hoop, how come basketball games don't just end within 2 minutes?"

 

The above question is flawed in the following ways:

 

 

1. It assumes it is easy to throw a ball straight into the hoop.
   It might not be that easy.
   
2. It assumes that the act of throwing a ball into the hoop is enough to end a game.
   There's a lot more to a game.
   

The same is true of the original question. The original question is, in itself, flawed, because

 

1. It assumes the formation of life is easy.
   It might not have been that easy, which would explain why (perhaps) it didn't happen again.
   
2. It assumes that the formation of life is enough for that life to take over enough "space" for it to be noticeable.
   Life might have actually formed independently again (as some people on the thread pointed out) but either was overtaken by the life that is already way more evolved, or died off at some point.
   

In short, the question ITSELF assumes conclusions that aren't necessarily true. And other posters in that thread showed a few examples of the two misconceptions and how they might not be true.

 

Which only shows how - in science - it's so important not only to ask questions, but to be weary on how to phrase the questions, so that the question itself doesn't imply a conclusion before one can even be tested.

 

~moo

[Moontanman]

You seem to be under the assumption (as Davies is) that all biologists are looking for DNA. That is not so. In fact this is just a relatively recent technique. An organism, regarding whether it does possess DNA or not should do something measurable. However, each and every organism we were able to identify does possess DNA. If they are a significant number of alternative lifeforms around, we should be able to see even one single example of it by now.

 

 

You say significant, what number would be significant? .0001% ? if one out 10,000,000 microbes is non DNA life then that means there are non DNA life forms on our planet. Even one species of non DNA life form is significant. another question is why would you think that Non DNA life forms would be obvious by their metabolism by products? Can you look at the biosphere of the Earth and extrapolate backward that everything we see is the result of DNA life? You seem to be assuming that a non DNA life form would be producing something so strange it would stick out. I think that non DNA life forms , to survive, would have to be part of the natural cycle of life we see already and so would not stand out as different just from their by products. I suggest any life forms on the Earth would have to be a part of the same cycles we already see simply because they would have to adapt to life with DNA life forms or die out. Unless they inhabit some odd place where DNA life cannot exist and we never look there. Would we see silicone microbes being brought up by lava in volcano's? I agree that they don't have to exist but I think it cannot be ruled out completely. Nessie has been ruled out completely, sea serpents are almost certainly sighting of known organisms. The Kraken was thought to be imaginary as Nessie until we realized giant squid existed and accounted for the sightings. Looking is a good idea, it's the assuming that is bad, assuming there is non DNA life is bad, assuming it cannot be is just as bad.

 

If we assume they are present and even plentiful, but we are just no able to see them, well what is the difference to the invisible unicorn, or Nessy?

 

 

You do make a good point but I think non DNA microbes are less likely to have an obvious effect than invisible unicorns, invisible unicorns have to eat, they would leave physical traces on the Earth and if they existed they could be detected, looking for Nessie has shown it not to be real. I see no reason to just assume there cannot be any non DNA life on the earth.

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My question is:

"If life formed so early in the history of the Earth, thereby implying that it was a more likely event than we think, how come we see only evidence of 1 type of life on the Earth? Why does the tree of life only trace life's history only to one primordial life form? Why aren't there more trees of life?"

 

I think you are looking at this wrong, it's thought by many that life did indeed start in many different places and some of these did indeed die out but it is also thought that many of them merged in one way or anther to form the ancestors of life. If you must use the tree analogy think of them as the roots of the tree merging to become the trunk. RNA viruses are thought by some to be evidence of this, they are shadow, a remnant of at least one of those linages. It has been postulated their might still be RNA life forms on the earth other than RNA viruses and just not being seen as what they are or more likely being very rare or existing in places where we don't look or don't think to look. it's a complex idea and as charonY has pointed out there are lots of competing ideas and little evidence of anything but DNA life.

[Aitor]

To those who mentioned that I am going about my question in a quite wrong way, like I am a moron, I say this:

My question is meant to trigger a discussion on current debatable views of the scientific community, it is not meant to be perfect or to be free of misconceptions. It is meant to make people discuss these VERY misconceptions. There is therefore no need to demean me like I am an idiot who doesn't know what he is talking about.

 

I think people here need to be careful how they formulate their reply, as it sometimes comes across as patronising, arrogant and rude. A bit more respect, please! We debate, we discuss, we don't judge.

 

Thanks.

[Phi for All]

To those who mentioned that I am going about my question in a quite wrong way, like I am a moron, I say this:

My question is meant to trigger a discussion on current debatable views of the scientific community, it is not meant to be perfect or to be free of misconceptions. It is meant to make people discuss these VERY misconceptions. There is therefore no need to demean me like I am an idiot who doesn't know what he is talking about.

 

I think people here need to be careful how they formulate their reply, as it sometimes comes across as patronising, arrogant and rude. A bit more respect, please! We debate, we discuss, we don't judge.

 

Thanks.

Judgment is unavoidable, I'm afraid, but I think you're over-reacting here. Just because someone suggests you're looking at something in the wrong way doesn't mean they're calling you a moron, or that you don't know what you're talking about. We often fixate on a certain perspective and it's one of the great merits of a discussion board to have other perspectives pointed out.

 

I think it's quite obvious when people are being patronizing, arrogant and rude, and I see none of that here. It's important to be civil, yes, but it's also important to not be so sensitive to correction or disagreement. Learning from differing perspectives is just as valid as learning by teaching, or learning from making mistakes.

[Moontanman]

To those who mentioned that I am going about my question in a quite wrong way, like I am a moron, I say this:

My question is meant to trigger a discussion on current debatable views of the scientific community, it is not meant to be perfect or to be free of misconceptions. It is meant to make people discuss these VERY misconceptions. There is therefore no need to demean me like I am an idiot who doesn't know what he is talking about.

 

I think people here need to be careful how they formulate their reply, as it sometimes comes across as patronising, arrogant and rude. A bit more respect, please! We debate, we discuss, we don't judge.

 

Thanks.

 

In no way did I say or mean you are a moron, your question is difficult to answer since it proposes that life is a way that it is not. life on earth did not originate from one thing, it was almost certainly an amalgam of several things that were by themselves very different than what your question proposes was the origin of life. No one organism was the ancestor, many different bits and pieces came together to form life as we know it, so many crosses and merging and splittings it is not accurate to say one thing suddenly woke up and became life as we know it. Even today microbes laterally transfer genes commonly and the more primitive they are the more lateral gene transfers takes place. The idea that life originated from one cell is a strawman argument often used by creationist types to try to disprove evolution. I assumed you were not one of those and were seriously asking an intelligent question and I answered it appropriately.

[Aitor]

Apologies for my feeling touchy recently. I was not having a good week. I tend to have surges of paranoia when I am stressed. Rather embarrassing when it flares up.

 

Anyway, I enjoy the feedback from everyone. The original question is indeed quite narrow in its formulation and we can now summarise the results of the debate as follows:

 

Life as we know it is successful because its design has allowed it to be so over other life designs, and this explains why we cannot see other types of life.

 

Other life designs may be occurring all the time, in various places, but their less "fit" form makes them vulnerable to "attack" from the dominant life around, therefore not allowing them to expand to significant numbers to be observable and self-sustaining.

 

Current life is likely to have emerged through a rather chaotic build up from and exchanges of various "bits" that would not individually likely lead to a successful life form. When the current life finally emerged from all these trials and errors, it was able to take over everything else. However, it does not prevent this build-up process from occurring again, and it probably keeps occurring, but we wouldn't notice easily as it would not lead to anything different from what is currently observable.

 

So now, based on the above summary of everyone's wisdom so far: are we entitled to state that the most likely life design aliens would take is ours?

 

(This would almost support Star Trek writers' assumptions that aliens are biologically compatible enough to spawn hybrid progeny without any problem! What about that for lateral genetic exchange?! )

[Mokele]

are we entitled to state that the most likely life design aliens would take is ours?

 

Nope. Remember, some aspects of our success are due to selective advantage, but other aspects may just be due to plain old luck. Maybe there was a "better" form of life, but a volcano erupted and destroyed them all? Evolution and extinction depend to a surprising degree on plain old luck.

 

Also, other planets likely have different selective factors (different temperatures, levels of sunlight, mineral abundance, etc.)

 

 

As far as Star Trek, it's utterly ridiculous. We can't even spawn progeny with other apes, much less with something that evolved on another planet.

[Aitor]

Nope. Remember, some aspects of our success are due to selective advantage, but other aspects may just be due to plain old luck. Maybe there was a "better" form of life, but a volcano erupted and destroyed them all? Evolution and extinction depend to a surprising degree on plain old luck.

 

Yes, plain old luck has a large part to play, but as far as fundamentals are concerned, if some are very advantageous to have, they should come around again after an initial obliteration. It's just chemistry, after all. Anything more complex arising from that would be more sensitive to random change. We can safely assume that we won't ever meet human-like creatures from other planets as a result, even if aliens may well have our life design.

 

 

As far as Star Trek, it's utterly ridiculous. We can't even spawn progeny with other apes, much less with something that evolved on another planet.

I definitely agree!

[Tyler Durden]

Evidence suggests that life appeared very soon after the Earth formed. Right. This means that life can form easily. OK so far. But

if life formed so easily, why has it appeared only once in Earth's history?

 

Surely, if it can be produced easily, it should have come up in several places in various forms and the descendants of each life strand would somehow have left evidence of their existence. But there is only evidence of the current life.

 

The only 2 things I can suggest are that:

 

1) Life appeared at the beginning in many ways and many places on the primordial Earth, but only the current one was selected by evolution. Which then would suggest that the conditions at the time of the birth of life were so alien to what we see now anywhere on the Earth that only 1 strand managed to evolve quickly enough to stay around until the present day.

 

It also means that not a single one of the different environments on Earth today are good enough to produce life from inert material, otherwise there would be places on Earth where life comes up from non-living stuff all the time.

 

So what is it likely to take to make life from inert material? Where else in our solar system could we find these conditions? How likely would these conditions be found in other stellar systems?

 

2) Life appeared in many chemical forms, but somehow all had in common the cellular structure and the ATGCU bases of RNA, which were the sine qua non of what turns inert stuff into living structures. This would imply that if life is found somewhere else in the Universe, it would also use the same stuff and basic structure as "our life", and would be not-so-alien to us. Is there really nothing else that could yield life?

 

So, to conclude:

Am I missing something? Have scientists already managed to answer part of my Question? Has anyone ever asked my Question?

 

 

I think this is a great question. Considering the age of the universe, 15+ trillion years, why didn't the Earth contain life a lot sooner? Surely 1 trillion years after the universe "started", we would've had definite solar system and planet formation, easily. Yet....the earth is only 6 billion years old. Why isn't it older?

 

And furthermore, if Earth is only 6 billion years old, there HAS to be other life-forms in the universe, considering there's over 100 billion galaxies, each containing billions of stars and planets. And these life forms, at least some of them, MUST be more highly advanced than we are, considering how much time has passed during the universe's expansion.

 

There's at least a couple sites on Earth where the ground has turned into complete glass, suggesting very high temperatures. I'm not sure where I read it, but that's strong evidence for a high powered thermonuclear blast, and that is not part of our history. So maybe life did exist more than once on our planet, and we have the timeline wrong. I don't know...there could be a possibility of life living deep underground Earth's surface and us not knowing it (but doubtful). Visitation from other planets is possible as well, especially since humans only occupy a very tiny portion of the Earth's history, so we might not have even remembered them, or been around when they were. Who knows...after all, evidence of civilizations disappear very quickly on a planet with weather patterns, and by quickly, I mean, all it takes is a million years or so for all evidence to disappear.

 

Yet a mere footprint on our moon will stay intact for over 25,000 years.

[Aitor]

Thanks for your enthusiasm on the subject, Tyler.

 

I noticed some of your facts are a "little" inaccurate: the Universe is actually only a bit less than 14 billion years old, i.e., about 3 times the age of the Earth.

The solar system as a whole is rich in all sorts of elements heavier than lithium because it is born out of the remnants of a large star that died in a supernova many billion years ago, and it itself came from the enriched death throes of other rather primordial stars before that. After each stellar death, it takes time for the material to coalesce again to form new stars and planets, and these guys live for a few 100 to 1000 million years.

 

All this to say: this is why the Earth only came to be about 4.5 billion years ago.

 

Meanwhile, life will have appeared on other planets in other parts of the Universe. Whether some of the life forms it gave rise to had a chance to explore space around their world, let alone reach the early Earth, is quite debatable. However, life does not have to be intelligent to travel in space. Bacteria are rather suited to that activity. Maybe life on Earth was seeded by a stray meteorite contaminated with unicellular organisms or even just RNA created somewhere else in our Universe.

 

As for the glassy terrain you mention: many things can do this: the most probable would be meteorite impacts, but natural nuclear reactors (arising from a critical concentration of radioactive material) exist or have existed, and can turn their surroundings into glass through super heating.

 

Finally, I have the feeling that it may take many more years than 25000 to erase the first footprint of Man on the Moon.