Question about limits of evolution:

[urbanxy]

I understand the theory of evolution does not speak to the question of the origins of life. My question is: how far back does evolution take us before "passing the baton" to other scientific disciplines (abiogenesis, etc.)? What is evolution's rear limit?

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[TeddyKGB]

Evolution, by definition, requires something that will evolve. In the case before us, that entails something that will replicate imperfectly. Thus, the first proto-organism was not produced by evolution, but the first proto-organism's slightly different offspring was.

 

[ChrisPelletier]

It's a hard one to nail. Not because there isn't evidence, but because it is hard to define "what is life?" Should we consider self replicating nucleic acids under evolution? They certianly are being selected for, but they're just compounds, much like a virus (which the general scientific community doesn't consider alive).

But this kind of question is a great one for a forum such as this to flesh out.

 

[Dr.GH]

Carl Wose argues for a "preDarwinian" evolution where the first life exists and evolved through lateral transfer of enzymes and short nucleic acid fragments.

Woese, Carl
1998 "The universal ancestor" PNAS Vol. 95, Issue 12, 6854-6859, June 9

Woese, Carl
2002 "On the evolution of Cells" PNAS Vol. 99 13:8742-8747, June 25

 

[urbanxy]

...it is hard to define "what is life?" Should we consider self replicating nucleic acids under evolution? They certianly are being selected for, but they're just compounds, much like a virus (which the general scientific community doesn't consider alive).

I would consider self-replicating organic compounds under evolution if they demonstrate descent with modification. I think this would include viruses (is this correct?).

 

[ChrisPelletier]

I would consider self-replicating organic compounds under evolution if they demonstrate descent with modification. I think this would include viruses (is this correct?).

Oh yes, i do beleive you are correct. I would consider viruses and mutatable self-replicating organic compounds able to undergo evolution.

I suppose my inquiry of life/non-life is for another debate.

 

[Blackmarch]

I understand the theory of evolution does not speak to the question of the origins of life. My question is: how far back does evolution take us before "passing the baton" to other scientific disciplines (abiogenesis, etc.)? What is evolution's rear limit?

.

Evolution itself does not explain anything about any stage of life/history.. merely the process of hereditary change, and that once there are eneugh changes between one group and another you'll get a seperate species.

This process is used as a backbone for first life theories.

 

[urbanxy]

This process is used as a backbone for first life theories.

Can you explain this some? Is evolution extrapolated backward to form a theory of life origins?

 

[Gracchus]

I suggest that biology is about cellular organisms. This definition produces some oddities. There was evolution before life, and some viruses may have evolved from cells, so we may have non-living things evolving from living things.

Like all definitions it is arbitrary, but useful as long as we remember that it is not a reality. Sociology is psychology is biology is chemistry is physics, is cosmology. It is all one thing we are studying.

 

[Blackmarch]

Can you explain this some? Is evolution extrapolated backward to form a theory of life origins?

Pretty much, but also use in the process more than just evolution theory- for example the study of species and the differences and similarities among them.

Not quite sure how it works for the conversion from non organic to proto-organic (which is a "sticky" point- the how really hasn't been sufficiently answered yet).. although from there the acids and whatever used to make the first simple protocells or amino acids, would likely have come from accidental combinations that utilised solar radiation and perhaps even CO2 to do something, and the ones that combined with other ones were more likely to have stayed around longer in form and structure then individual ones. this could be seen as a helpful error which provides better survivability and eventually through further envirenmental influence and form mutation/error one of these would have an ability to regenerate and/or replicate it self.
Eventually these processes and changes occur eneugh that a more complex form emerges, and from there, over time newer and more complex organisms are generated .. culminating in millions of years later in all the species currently on our planet