artificial life

[illogical]

evolution seems to provide a mechanism whereby single celled organisms can turn into intelligent forms.

but how did life begin? the experiments involving lightning and chemicals only produce complex molecules. if they added high-energy cosmic rays, would that knock aroound enough molecules to produce viruses?

early earth may have been bombarded by radiation much greater than anything that can be effectively simulated.

 

[Graham Jackman]

evolution seems to provide a mechanism whereby single celled organisms can turn into intelligent forms.

but how did life begin? the experiments involving lightning and chemicals only produce complex molecules. if they added high-energy cosmic rays, would that knock aroound enough molecules to produce viruses?

early earth may have been bombarded by radiation much greater than anything that can be effectively simulated.

I don't think we could ever know the answer. Even if we were to generate a life form under such conditions, it only demonstrates plausibility and not necessarily the true origin. In any event, cosmic radiation is so energetic that it is more likely to completely destroy complex molecules than initiate its formation.

 

[Wowbagger]

As Jackman said, we may never know the complete answer. But, we can use scientific investigation to formulate plausible theories. Most of which fall under the collection of abiogenesis theories. When I have more time, I might provide more detail. In the meantime, you can look that word up, yourself, to find out what its all about.

 

[arthwollipot]

One point to remember is that abiogenesis is not the same thing as evolution. Evolution describes how populations of organisms change, not how they appeared in the first place. Darwin's book was titled "Origin of Species", not "Origin of Life".

Abiogenesis is a largely speculative science at this time. All the evidence of that period of time has been wiped out by geological processes. It has been said that this is one of the few remaining Gaps for God to hide in. Personally I don't grant this - no other process requires a deity so far as we are aware so why should this?

There are a number of theories though, some of which are moderately plausible. It is important to remember that whatever primitive replicator kicked it all off may have little or no resemblance to the modern, metabolising cell clusters we now recognise as "life".

 

[Wowbagger]

Although abiogenesis and evolution are treated as separate subjects, by us humans, I think it is also important to remember that the two are so closely related to each other, that when the subject of life origins is brought up in a discussion about evolution, it is generally worth embarking on, at least for a little while.
After all, the difference is invisible in the "eyes" of nature.

 

[arthwollipot]

Kinda sorta. But when creationists claim "evolution can't explain the origin of life" you have to agree with them. They hate that.

 

[Wowbagger]

Kinda sorta. But when creationists claim "evolution can't explain the origin of life" you have to agree with them. They hate that.

WRONG! Any viable abiogenesis theory is likely to have emerged from an evolutionary process, similar to that which applies to life forms as we know it! We may not know which theory is the more likely to have happened. But, any abiogenesis-related theory that implies gradual "evolutionary" stages, is probably more-likely correct, than one that does not.

When a creationist brings up such a claim, I feel it is important to give them this type of response.

 

[Dorian Gray]

A better response is "neither does geography - what's your point?"

 

[neutrino_cannon]

early earth may have been bombarded by radiation much greater than anything that can be effectively simulated.

Everyone else has addressed the abiogenesis point, so I'm curious about this.

Is there any reason, given what we know about stellar evolution, to think that c. 3 billion years ago solar output was significantly harsher than it is now?

Given that there was no photosynthesis going on pre-life, I suppose there might be no ozone layer due to lack of liberated oxygen. On the other hand, I recall reading that some scientists suspect that there was a significant amount of nonbiogenic oxygen present in the atmosphere before the advent of life, so perhaps that's not true either.

 

[Soapy Sam]

If there was no ozone layer there would be more radiation reaching the surface, even if solar output was the same or less.

Note- viruses are parasitic data replicators which need to hijack the reproductive apparatus of a cell to reproduce. As such, they are likely to be relative latecomers and not a likely contender for earliest lifeforms.

There are numerous suggestions for proto lifeforms which might have given rise to organic life. Silicate templates are a possibility.

 

[Wowbagger]

A better response is "neither does geography - what's your point?"

Yeah, that's a cool, concise come-back, and all.

But, I think that since evolution and abiogenesis are so-closely linked, evolution has a smaller gap for explaining the origins of life, than geography.

 

[arthwollipot]

WRONG! Any viable abiogenesis theory is likely to have emerged from an evolutionary process, similar to that which applies to life forms as we know it! We may not know which theory is the more likely to have happened. But, any abiogenesis-related theory that implies gradual "evolutionary" stages, is probably more-likely correct, than one that does not.

When a creationist brings up such a claim, I feel it is important to give them this type of response.

As far as I am aware, self-replication is a part of the evolutionary process. What abiogenesis is actually all about is the origin of self-replication. Once that gets going, then evolutionary processes can take over. I don't think it's accurate to suggest that an evolutionary process itself was involved in getting self-replication going, because that would lead to a circular argument.

 

[Cuddles]

Everyone else has addressed the abiogenesis point, so I'm curious about this.

Is there any reason, given what we know about stellar evolution, to think that c. 3 billion years ago solar output was significantly harsher than it is now?

Given that there was no photosynthesis going on pre-life, I suppose there might be no ozone layer due to lack of liberated oxygen. On the other hand, I recall reading that some scientists suspect that there was a significant amount of nonbiogenic oxygen present in the atmosphere before the advent of life, so perhaps that's not true either.

The early Sun was about 30% less bright than it is now. There would probably be higher levels of radiation during star formation, but by the time planets has formed it would have settled down to just being a normal star, with significantly less radiation that there is now.

The early atmosphere of the Earth was formed almost entirely by volcanic outgassing, so there was very little free oxygen present, although plenty locked up in water, carbon dioxide and sulphur dioxide. Since there was no oxygen, there wasn't an ozone layer either. this site has some nice stuff about the early Earth.