An Inquiry About Abiogenesis and Ancestry

[Carcharodon]

According to modern evolutionary theory (the dominant theory to explain the process of speciation), all life evolved from a single common ancestor.

The theory of abiogenesis suggests that this first ancestral organism came about from the proverbial, "primordial soup," an aqueous mixture of various organic compounds that reacted to form a self-replicating molecule (likely RNA to begin with) protected by a phospholipid (or some derivative) membrane. Side note: these membranous spheres/globules are known as protobionts and are quite easily created in a lab.

I'm over-simplifying, of course, but this isn't my main point...

Now, most people who accept this theory believe that there was one truly common ancestor, and what's more, those that don't subscribe to the theory cite the idea that the chances of these reactions occurring spontaneously (I use the term losely, not adhering to the strict chemical definition of the word) are too small to even consider plausible.

On the other hand: consider the relative scale of these reactions, and the potentially vast amounts of reagents we could possibly have had to work with. Doesn't it stand to reason that these reactions AND similar reactions would have been taking place billions upon billions upon perhaps trillions of times? The idea that the formation of these compounds was simply an isolated incident defies all logic (and, frankly, the available evidence) and gives credence to those that cite improbability as a counter-argument to the theory of abiogenesis.

Therefore, doesn't it seem odd that only one ancestral cell (or, "prototype organism," if you will) would have formed? That seems less likely to me than the idea that nothing should have formed at all from these reactions.

Thoughts, ideas?

 

[C. Lee]

The right combination could have formed together many times....that doesn't mean they all survived.....thus, the forming can be very rare....but still be accounted for as only one source (or more properly....only one surviving source).

 

[Carcharodon]

The right combination could have formed together many times....that doesn't mean they all survived.....thus, the forming can be very rare....but still be accounted for as only one source (or more properly....only one surviving source).

See, that's the stretch: that these various combinations did form, but some force or circumstance caused all of them to die but one.

Of course, it's not impossible. However, all you ever really hear about is that first cell when it comes to abiogenesis, as though scientists are absolutely certain of just one universal common ancestor. You almost never hear mention of that cell's abiogenic compatriots.

 

[Danalys]

i think it's the fact that its a replicator that makes it unique. it would use up the components that created it in replicating itself. thus making it impossible for other replicators to form in the same place that had the special conditions required.

 

[Carcharodon]

i think it's the fact that its a replicator that makes it unique. it would use up the components that created it in replicating itself. thus making it impossible for other replicators to form in the same place that had the special conditions required.

If it used up all the components, wouldn't that also prevent itself from being able to replicate down the road?

I do agree with you that the ability to replicate probably played a role, though. The mechanism would likely have been a lot more primitive than it is today as well (even by prokaryotic standards), so perhaps it required less raw materials to begin with (by that I mean enzymes, etc).

 

[Danalys]

well there's recycling of dead replicators so they can replicate more. but anyway i'm not to concerned with the details. i just find it probable that a first replicator wouild have a significant effect enough to preclude the formation of other replicators, atleast over the time scale that it would be likely for another replicator to form through abiogenesis.

 

[Kent]

Thinking about how quickly microorganisms spread when there's no competition or other problems I'd assume any proto-organism to be "first on site" would have time to grow in population (approximately exponentially in time) to the point that any newcomer would find itself severely outnumbered.

I mean, hypothetically, if there was no resistance to spreading (assuming exponential growth), a population of microorganisms could literally cover the entire Earth in a matter of days. Any head start would give the first proto-organism a definite edge in terms of numbers.

So once competition kicked in between different types of proto-organisms the one first on site would have a team much larger than any other team.

 

[Carcharodon]

So once competition kicked in between different types of proto-organisms the one first on site would have a team much larger than any other team.

...back from the dead.

That's also an interesting point...however, why would one have to necessarily wipe the other one out? I'd also imagine that mutation (and likely speciation) would occur amazingly rapidly, especially given the rather (assumed) primitive mechanisms of replication.

I guess that also raises the question of whether or not evolution or speciation was able to progress only when the parent population was greatly reduced somehow?

Jeez, it would be so great to be able to go back and study all of this somehow. t: The dynamics of the first organismal populations...there's just so much we have no clue about...

 

[C. Lee]

See, that's the stretch: that these various combinations did form, but some force or circumstance caused all of them to die but one.

Of course, it's not impossible. However, all you ever really hear about is that first cell when it comes to abiogenesis, as though scientists are absolutely certain of just one universal common ancestor. You almost never hear mention of that cell's abiogenic compatriots.

I personally have a hard time accepting that scientists say they can trace something back to one single organic enity. If you look around you...things are constantly in flux. Organisms are born, live, reproduce, die, and the process starts over again. Who species die out....there are mutations....there things not found.....the possibilities are endless.