For Yung'N

Background:

I wrote a piece for Dale, posted it on Yung'N's wall, and a little conversation ensued. Yung'N asked me a few questions and I said I would respond. Here is his message to me on FB:

I got you, yes please explain to me how the first cells got "here" because that is all I wanted to know. Where did they or it come from? How did it create itself from nothing? Why? Why did they need to evolve if there was no reason to (no need for survival of the fittest then, etc)? How did something non-living evolve to living? And how come we haven't ever seen a non-living thing become alive? Just a few random thoughts.

So this is what I will set out to do with this post.  I will address:

1. How the first cells 'got here' and how they were able to self assemble.

2. Why haven't we seen anything non-living become alive?/ How did we make the jump from non-living to living?
 
             2b.  How did the first cells evolve?

So let's begin!


There are really great, though technical, pieces that really answer what you're asking here and here. However, I really want to break it down in to terms that are much easier to understand.

1. How the first cells 'got here' and how they were able to self assemble.

Think back 3.8 billion years ago. (I know, my memory is a little hazy too.) Think of what earth looked like- I represent it like we tend to represent other rocky planets; dead and lifeless. Except earth had slightly more water than our neighbors. There was also little or no oxygen in the atmosphere. And this is key- the formation of cells directly relates to properties of water and how molecules interact in the absence of oxygen. Organic molecules are "reduced" meaning (I am over simplifying greatly) that they are able to grab free electrons and able to bond to each other.

This means that over time, organic molecules could bond together forming larger and larger molecules. This also means that, a phospholipid bi-layer could form. And what is a phospholipid bilayer? This:



So why is this important? Well simply put- this is the 'skin' of the cell known as the plasma membrane.  

And there we have it; little tiny things that are somewhat similar to bubbles. Because of the properties of the bilayer- liquid H20 is able to freely move in and out. These were the first proto-cells.

I am leaving this here. That is how a cell can arise purely through environment  under the right conditions. All three of your questions blend into each other, so the remainder of this answer will be in the next part.

2a. Why haven't we seen anything non-living become alive?/ How did we make the jump from non-living to living?

             2b.  How did the first cells evolve


2a. Quick answer: Because we do not yet have the resources available to mimic the right necessary for life in a laboratory. (We can create the building blocks of life; we can even animate cells. We just aren't too sure if these were the conditions present when the earth was still young.)

 Making the jump from non-living to living is going to be hard to explain, because, put simply-right now we cannot be 100% certain how this occurred. However, that doesn't mean we don't have some damn solid ideas that are evidence- based. There are some factors that make it next to impossible (at least right now, September 2011) to recreate the conditions that were present on a young (750 million year old) earth.

To quote Darwin on the matter:

(sic) the original spark of life may have begun in a "warm little pond, with all sorts of ammonia and phosphoric salts, lights, heat, electricity, etc. present, so that a protein compound was chemically formed ready to undergo still more complex changes". (Darwin) went on to explain that "at the present day such matter would be instantly devoured or absorbed, which would not have been the case before living creatures were formed.

 [taken from wikipedia]

This in mind, here are some of the models that we have created to explain what evidence we do have. I invite you to read them, play around a little. Again, they are highly technical, so some engagement is required.

http://en.wikipedia.org/wiki/Abiogenesis#Current_models

This link deals with abiogenesis, which is the origin of life (Remember- this is different than speciation via evolution. The key difference here is that two completely different things are trying to be explained. We are still working on abiogenesis, with some amazing work being done in my home state, by the way!) However, we do know how single celled prokaryotes evolved into eukaryotes. I think this is what you meant by the "how did the first cells evolve."

2b. The evidence we have that we (Eukaryota) evolved from prokaryota is very significant- and very plentiful. In fact, the evidence is inside of each of your cells. We all know that we have our own, unique DNA- but what many people don't know is that we also carry an ancient (and unrelated to our own) DNA. This 'other' genetic material is found in the mitochondria, one of the tiny organelles in our cells that generates energy to do cellular work.

So why do we carry a second genome? Well this link, explains it far better than I can. Essentially,  through endosymbiosis, a large organism munched a smaller one, but it was more beneficial for the both cells that the smaller one wasn't digested. For example, the smaller cell's waste could give the larger cell more nourishment than simply digesting it.

This is evidence because we know that at a point in evolutionary history, two cells were able to form an become a larger organism. There existed a two- celled organism, where previously only one was possible.

Discussion:
I really hope you read this, and engage with it. But don't think I hold all the answers- do your own research, ask experts. Look at credentials. If someone is telling you something, make sure they have the evidence to back it up. Make sure they have spent more time in a lab and not in the pulpit. I am not an expert. I do not have my PhD. But I can support what I claim by citing the work of experts.

Secondly; science does not have the answer to everything- yet. We still have to work out abiogenesis, and replicate processes by which life arose, in the lab. However, this does not mean that you can just say "Ha! You can't answer that, therefore my idea on the origin of life is correct." It means that we still do not know. It means that if you want to be correct, that goddidit, you still have a load of work to do to support your claim. You still have to gather evidence- and pointing a passage in Genesis is not evidence. You have to show the actual mechanism that your god used. Because without that, your claim is just as worthless as every other creation myth on the planet.

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References:

http://www.sciencemag.org/content/316/5824/542.3.short

http://www.infoplease.com/cig/biology/eukaryote-evolution.html

http://www.sciencemag.org/content/256/5057/622.short

http://www.springerlink.com/content/x648g3r871311921/

http://www.sciencemag.org/content/283/5407/1476.short