Just wondering, has any new knowledge about how life started come to the fore since Stanley Millers experiment whereby simple amino acids were created from a soup of chemicals???
Specifically is it possible even today or the near future (do u think) that we will be able to produce living from the non-living?

<blockquote><I>Just wondering, has any new knowledge about how life started come to the fore since Stanley Millers experiment whereby simple amino acids were created from a soup of chemicals???</I></blockquote>
The relevance of the Urey-Millar experiment, although it remains an interesting exercise, has been downplayed in recent years because the prevailing theory amongst geologists now is that the Earth’s atmosphere at the time that life is thought to have originated (~ 4 bya) was nothing like the conditions that Urey-Millar created in their reaction vessel.

I suppose there are 2 prevailing theories that have developed over the last decade or so: the RNA World theory and the subterranean evolution theory, both of which have an ever-growing amount of supporting evidence.

The RNA world theory says that the precursors to life were autocatalytic RNA molecules (or analogues) that were able to self-replicate. These eventually became encased in lipid micelles to form a primitive cell-like entity. DNA-based cells evolved later.

The subterranean evolution theory says that the first life on Earth evolved deep in the crust of the earth and not in “primordial soup” pools of water on the surface that were first proposed as far back as Darwin. This may seem counter-intuitive as the Earth’s crust is very hot and very noxious, but there are bacteria that live in the crust as far down as we are able to drill. Furthermore, they are archaebacteria, the oldest lifeforms on the earth. These bacteria are the so-called “extremophiles” that thrive in high pressures and in temperatures at or above boiling point and can happily use the abundant sulphur compounds as an energy source. The conditions deep down in the Earth’s crust are more similar to what existed at the time life first arose than anywhere else on earth. When life first arose 4bya, the Earth was being bombarded by huge meteorites that would have vaporized and sterilized much of the planet’s water with each impact, so deep down in the crust was the only safe place on the planet for life to arise.


<blockquote><I>Specifically is it possible even today or the near future (do u think) that we will be able to produce living from the non-living?</I></blockquote>
No, we are not even close, nor will we be for a very long time.

About 18 months ago, a team managed to artificially synthesize the complete polio virus genome. When they incubated their artificial genome with whole cell extracts, it was capable of producing new polio virus particles that were shown to be infective and indistinguishable from normal viral particles (with the exception of the molecular marker they inserted into the artificial genome). So I suppose it can be said that scientists have created an infective particle from scratch. Mind you, polio is a very small and simple virus and it is not possible to use the same technique to produce much larger and more complex viruses, such as smallpox.

There is a consortium that is attempting to “sort of” artificially synthesize a bacterium. They are using a species of Mycoplasma because Mycoplasma is the smallest known bacteria with the smallest known genomes. They will attempt to artificially synthesize the whole bacterial chromosome, remove the DNA from a cell, then introduce their artificial chromosome into the cell and see if the cell can function normally. So it’s not really creating life because they need a living cell I the first place to accommodate their artificial chromosome. We are a long long long way from being able to create a living cell from scratch.

I’m sorry I don’t have refs or links to anything I’ve said here, but I’m not at my usual computer where I have all my stuff stored. I’m sure you can find info for everything I’ve said quite easily.

So I guess that the fact that we cannot yet create life from scratch would indicate that we do not fully know the science of creation (of life). For example the two theories u mention give locations on earth where life may have originated but do they give precise details on how autocatalytic RNA molecules themselves were created? Or even how lipid cell encasement came about?
These are what we must understand before we can understand how the inanimate can give rise to life.

<I>So I guess that the fact that we cannot yet create life from scratch would indicate that we do not fully know the science of creation (of life).</I>

Yes, I think it’s safe to say that. :)

<I>For example the two theories u mention give locations on earth where life may have originated but do they give precise details on how autocatalytic RNA molecules themselves were created? Or even how lipid cell encasement came about?</I>

These theories take the formation of first life back to the stage where the components needed for life can form naturally and spontaneously as a result of natural environmental chemical reactions. Phosphates can react naturally with ribose sugars. Ribose sugars can reaction naturally with pyrimidine or purine bases. Lipids with hydrophilic and hydrophobic ends will naturally form micelles in water. All these carbon molecules were present (or at least their simpler carbon components were present) at the time that life first appeared. Given some time, it’s not inconceivable at all that these molecules could come together to form a small RNA encased in a lipid shell as a result of totally random and natural processes. The whole process becomes even easier if the sugars and amino acids needed for life did not have to form from scratch from natural chemical reactions, but were instead seeded here in the first place by comets and/or meteorites. We know that our galaxy is full of hydrocarbon molecules such as amino acids and simple sugar precursors.

Of course, it the panspermia hypothesis is correct, then the formation of life of earth is a bit of a moot point – we are all aliens! :eek:

Note: I should say that the organic chemistry of the early earth is not my field, so don't take everything I'm saying as gospel. I'm just recalling stuff from memory from my casual reading on this subject.

If what u are saying is correct, then we cannot be really called aliens as LIFE still formed on our planet. Its just the inanimate sugars and amino acids that were seeded here.

So presuming these lipid shells could form naturally and spontaneously, the most important property of living matter is the ability to replicate itself. Do scientists know yet how this process came about?