Could our ultimate evolutionary source lie with complex organic molecules capable of replicating themselves.

Amazing article:
http://www.cogsci.indiana.edu/farg/harry/b...t/lifestart.htm
Includes a nifty simulation of the begginings of cell reproduction on Earth.

I'd love to hear peoples' thoughts. This has interesting implications for the ability of life to arise on other planets.

Kashi

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Climate Change Australia

I have suspected (I'm not an expert in biology) that there must have been something we would call evolution before there was what we now call living organisms. It makes great sense that it all is the result simply of the laws of nature and the properties of matter.

Indeed. It's obvious that evolution can, does, and has occured. But what's a bit less known, is whether "life" can come out of nothing (i.e. just chemical compounds) when molecules randomly collide.

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Climate Change Australia

Thats probably what occured, or a huge bolt of lightning struck the ocean and created life.

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MacTalk - The Australian Apple Community - iPod, iPhone and Mac.

Large inputs of energy was probably required, if the temperature is too low the possibilities are less.

Well the higher the temperature, the greater energy atoms/molecules have to move around increasing their chance of hitting one another increasing the chance of a reaction.

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MacTalk - The Australian Apple Community - iPod, iPhone and Mac.

That's a very a good point. I guess that means all the other variables that affect rate of reaction would also have an impact on the length of time it took life to establish. Small volumes of water containing larger amounts of minerals, moving currents in the water etc.

Maybe the amount of available energy (kinetic, electrical etc.) on a planet could be a valid variable to include in the drake equation. What do you think?

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Climate Change Australia

It would be. Lightning may have been what 'started' the chemical reactions which created life on Earth. So energy is the main variable (I think) for there being life. If there was no energy, then there would be no chemical reactions.

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MacTalk - The Australian Apple Community - iPod, iPhone and Mac.

The Drake equation: N = R* x fp x ne x fl x fi x fc x L

The variables ne (the number of planets per solar system with an environment suitable for life) and fl (the fraction of suitable planets where life appears) could perhaps be more refined if we knew anything about what role the energy amount plays... or, it could be another variable on its own perhaps.

What do all the other variable mean, Parker?

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MacTalk - The Australian Apple Community - iPod, iPhone and Mac.

N=Number of communicative civilizations in this galaxy

R*=The rate of formation of suitable stars (every year)
fp=The fraction of those stars with planets
ne=The number number of planets in the habitable zone per planetary system
fl=The fraction of those planets where life develops
fi=The fraction life sites where intelligence develops
fc=The fraction of planets where technology develops (to the point where they can do and desire interstellar communication)
L=The "Lifetime" of communicating civilizations (in years)

This equation can of course not estimate the number of technological civilizations including those who cannot or wish not communicate, and not non-technological but intelligent species either, so the number of intelligent species in the galaxy should be higher than N.

Drake equation:
http://www.space.com/searchforlife/seti_dr...e_equation.html
http://www.seds.org/~rme/drake.html

Here you can enter your own values:
http://www.seds.org/~rme/drakeeqn.htm

I'm going to ask the writer of that article to comment on what we have discussed (i.e. that immense energy could speed up the process of creating the first replicating molecules).

Kashi

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Climate Change Australia

What do you mean "Immense energy"?

An ample supply of molecules with oxidative potential?
A warm planet?
A sun?
Access to different radiation types?

The neat thing about a self-propulgating system is that, once it's started - it continues until it is stopped. IF, out of the chaos, a self-ordering system starts (such as life), then it's there. The odds of occurence are minute, but the neat thing is that once something has occurred, it's done.

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Live long enough to see Space!

We can get to space as a species. The above link is information about life-extension (living longer) so that you can personally see a space-based civilization.

The MPrize (a prize to encourage life extension research now contains over 3 million dollars.

Indeed. The simulation which is part of the original link I posted here shows that. Once you have a replicator molecule (which can take a while), you're unlikely to lose it, although it is possible (if it strikes a "poison" molecule that breaks it down).

Well originally Matthew suggested that a lightning bolt could have provided significant amounts of energy to speed up the rate of collision. A thought I just had though, is that it could also provide enough energy to break apart any replicator molecules already in existence. I think it is obviously a very complicated process with many variables involved.

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Climate Change Australia

Hi, thank you all for commenting on my web-page on the origins of life.

Some readers proposed lightning bolts as a source of sufficient energy for starting up reactions that would eventually lead to replicator molecules. I would like to make the following comments:

I don't think our current state of knowledge is sufficient to understand whether plenty of energy would be beneficial or detrimental. As one reader observed (Kashi, I think), a lightning could destroy what otherwise started gradually and inconspicuously. We simply don't know (yet). What I wanted to emphasize in my article was that even though we can't know the exact details at this point, we can, however, discern the overall pattern, the general principle under which life got started on our planet. This principle, of course, is known by biologists, but they are concerned more with the exact *conditions* (e.g., are lightnings good or bad?) that would be necessary for the first replicators to appear. To me, it seems more urgent at this point to stress that the mechanism is there and is known; the particulars can be discovered in the (hopefully near) future. My motivation is more philosophical, rather than purely scientific: I want to make these ideas known to non-scientists, who often view life as a miracle (that happened with supernatural intervention). I want to tell them: look, there doesn't have to be any supernatural intervention, it can all happen naturally.

Knowledge of the principle is also important for speculating about the nature of extraterrestrial life. If the chemical nature of matter "affords" (allows) replicators, we expect this to hold not only here, but in the entire universe (assuming the fundamental laws of matter are universal). The possibility for extraterrestrial life then becomes a question of "initial conditions". The principle (i.e., replicators) is analogous to a differential equation that describes an orbit; to have your orbiting object arrive where you want it, following your equation, you need appropriate initial conditions. Most scientists are concerned with the discovery of those conditions, rather than with an explanation of the principle. Regarding extraterrestrial life, however, we should be aware of the fact that it's conceivable that an environment can "solve the equation" (arrive at replicator molecules) starting from different initial conditions than those that prevailed 4 billion years ago on Earth. In this case, we would expect that such replicators would almost certainly have different properties than those we are familiar with (e.g.: no DNA). Or, it may be that chemistry (matter) affords only one solution: the one that leads to DNA. Then all extraterrestrial life would exhibit similar properties. In this case we would expect "mammals" and "birds" and "fish", and so on, everywhere where life appears/appeared in the universe.

What are the readers' opinions on the probability of extraterrestrial life? Sorry, I guess you have already discussed this. I just subscribed today and had no time to read what has been written. My own opinion (which doesn't matter much) is that those initial conditions must be pretty rare, else we should observe the signature of life in the part of the universe that is available to us for observation. But I would be delighted to know the opinion of others.

Thanks,
-Harry Foundalis.

Hello Foundalis, right now I have one question: do you think that in the forseeable future it will be possible to incorporate this or a similar theory into the theory of evolution? I realize that we might not be able to know exactly what happened on Earth, of course. Anyway, would such a theory be the link between physics and biology? If you know what I mean.

Hi Parker,

"Theory"? I am not proposing any theory. What I have in my page is called "armchair philosophy". That doesn't mean it's wrong -- I certainly don't mean to denigrate my own writings (I've yet to see an author who does!). But it definitely is not a theory. A theory is a system of propositions that explain experimental data. I don't have data to explain yet, ergo, no theory. Unless, of course, you consider the fact of the existence of life and its evolution as a single piece of datum, a prospect I think hardly any scientist would agree with.

The ideas in my page, however, *should be* part of the link between chemistry and biology. (I'd prefer to use "chemistry", rather than "physics", as you did, because at the level of very complex organic molecules it is the emergent laws of chemistry that are at work, rather than simply the laws of quantum mechanics; the latter stand at a lower level of description.)

How could one make a theory out of this set of ideas? One could attempt to simulate atoms and molecules in a much more realistic way than the elementary Java applet I present in my page. The more realistic the simulation, the more persuasive the argument. If one could simulate actual molecules in 3-D, and one arrived at real replicators, I guess that would count as "data", and it would be an enormous step forward in the issue of origins of life. Unfortunately, current computer speeds do not allow us to produce any realistic simulation, with the number of molecules that would be required for obtaining any result. Notice that I propose a computer simulation and not a real-materials experiment because in the former one has much more flexibility in toying with values of parameters, trying this, failing, trying that -- it can all be done much faster than real chemicals. Assuming much facter computers, of course.

What I meant was, can we form a theory that possibly would explain the origins of life similar to what your ideas did? And also, even if we through computer simulations could reach simple lifeforms and DNA, it would still only be one of many possibilities, right? I mean we wouldn't know for sure exactly how it happened, but would it still be enough?

A lightning bolt could provide the increase in energy to create a 'replicator', but you need only one replicator to replicate, if you have had enough replications by the next lightning strike at least one should survive. Allowing for more replications.

I think physics, chemistry and biology need to be used to understand the complexity of life, and how it emerges.

• Biology is life, the understanding about life.
• Chemistry explains how individual molecules interact
• Physics explains energy, and is inter-related with chemistry.

I know its a bit basic, but my list above does show that we need all three.

Explaining the origin of life and how possible it is, now seems so much more complex!

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MacTalk - The Australian Apple Community - iPod, iPhone and Mac.

Harry,

Welcome to the forum! There have been lots of posts related to the likelihood of extraterrestrial life occurring. This topic discusses possible reasons for why life is apparently not very common in the universe:

http://www.universetoday.com/forum/index.p...p?showtopic=843

It links to a great article from the Scientific American.

Kashi

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Climate Change Australia

Something from MIT regarding self replicating molecules:
http://web.mit.edu/newsoffice/tt/1990/may09/23124.html