Tuesday, 7 September 2010

On the origin of life

El origen de la vida - The origin of lifeImage by pericomart(pericomart.blogspot.com) via FlickrI've had this idea floating in my head for weeks now. So I'm finally getting round to putting down into words. I'm excited to finally express it but I hope I do it justice. Here goes.

We're all aware of the theory of evolution. It makes perfect sense to me how pressure for resources has lead to so much diversity in life over such a long time. However evolution does not account or even attempt to explain how life began, the origin of life, at all. It merely explains why change is the norm and that life is about adapting to change. 

What I have come to believe is that life is basically about the exchange of energy. With this exchange we can fuel all sorts of processes that have built up over time to the natural world we are used to. It also powers the amazing senses with which we get so much pleasure.However the exchange of energy must lead to processes which ultimately bring more energy into the organism so that more energy can be exchanged and the cost of converting the energy into another form must be less than the energy gained from the exchange.

It's exactly the same as the environmental problems we keep hearing about. Right now it takes more energy to get oil and coal etc out of the ground and into our cars as petrol and homes as electricity than the amount of energy actually produced. So it's taking from the environment without giving anything back to balance things out. So it's unsustainable. This certainly happened in the early days of this planet. The atmosphere was very different and the organisms that found life there eventually killed themselves off because they changed the atmosphere. So what was good for us was bad for them but they only have themselves to blame.

With this example, it strikes me that life in itself appears constant. Organisms live and die but there always seems to be something that's alive at any given point in time. This may not have always been the case but it seems so now. So the organisms that have life are constantly changing but there is always something that has life and often the death or demise of one species is required for another to live.

Studying biology I am always reminded of feedback loops. That insulin and glucagon work together to regulate sugar supply in our blood and cells. If there's too much sugar in the blood your body releases more insulin, if there's too little it releases more glucagon. Adult onset diabetes occurs when this natural feedback loop breaks down because the bodies cells no longer respond to insulin as they used to. The feedback loop that corrects this naturally is that of activity (exercise). The extra demand for sugar in the muscles forces the body to become more sensitive to insulin again correcting the diabetes and bringing your body back into balance. 

These feedback loops are so common that it's easy to feel that they are the basis of human life and most of nature. Each organism is simply a collection of feedback loops that all, in theory, balance each other to maintain life. Death often occurs when one or several of these loops is out of balance for a long time. 

This thinking lead me to believe that life itself really could be one long feedback loop. For example if you don't reproduce, then your gene pool could die. With so many humans on the planet it won't have such an impact now but back when there were only a few humans on the planet this really would have mattered. But essentially for a species to survive then it must either never die or it must produce enough offspring to replace those that are lost. For a species to grow it must naturally produce more offspring than are lost.

So the feedback loop and pattern must repeat itself. It doesn't matter what the pattern is, just that it must exist. If the loop stops then another species may thrive in its place but if nothing does then death could become permanent. I would say that life is the presence of a pattern, death is the absence of one. For example many organisms might survive but not produce viable offspring. So the life was fleeting but the death far more permanent.

The question of why all organisms need to reproduce and then die instead of living infinite lives seems simple for me as a programmer. Any application I create is only perfect for the fleeting time that it meets the needs of the environment. It's guaranteed that within just a few years the very foundation on which it is built will be out of date and require reworking. You can maintain and fix the application for many years and get good service but sooner or later the cost of reworking it becomes greater than building a new one from scratch. I generally rebuild every few years for this very reason. hence I kill my old application and framework that my new one shall live. Each new version competes better than the last because I've learnt more and the environment it's built from and sits in can do so much more.

So I believe nature has the same problem and came up with the same solution millions of years before we did for essentially the same reasons. Every organism is built with the best technology of its day. Due to constant change this technology will eventually become out of date. Thus a pattern which ensures the species is built using current and different technologies is a pattern that ensures survival of the species at the expense of the individual.

So how did it all start?
Well, it's through learning how stars created the elements that I figured out my idea for how the early patterns of life emerged. Again, the process of tars creating elements is based on energy exchange, in this case entropy. The disorder that entropy creates matches the constant change we see today. This leads to energy, at the scale of a star this is sufficient energy to change hydrogen to helium and then helium to a higher element. This process went on for billions of years until all the elements we now know of were formed. Longer still and the planets formed from the the gas clouds the stars produced.

Each step is part of multiple patterns that lead to it, fueled by energy and change. The stars are part of a feedback loop. The gases in space are drawn to each other to such a point that their combined gravity and friction ignites a furnace so hot it creates nuclear fusion. Fusion actually releases more energy than is used to create it and thus it becomes a self sustaining process, only dependent on sufficient elements to fuse together. When these run out the furnace dies and the stars dies in a massive explosion. Hence a star has a life cycle of birth, life and death and it eats elements and excretes other elements. So, while it's basically a massive chemical reaction, it's also like us in very basic ways. It ingests food/fuel and excretes waste product.

So that's the feedback loop that created the elements, but where did life come from?
The next step is that the elements have a habit of bunching together. We already know that gas clouds form. Well, larger elements also have a habit of joining together. I don't know all the details but you'd essentially need to add energy to the elements to get them moving and joining together. Over long enough periods you'd get elements joining together that could create basic structures that could create more of themselves. All based on the exchange of energy.

I'm a bit vague on this but the basic idea would be that a very simple ecosystem could exist where some elements would join together. This would then release energy and waste products, protons and other things. This would encourage other elements to join together given this new energy and waste. Basically chemical reactions would occur. The pattern being that one reaction triggers another, which then triggers another until a loop occurs. If no loop occurs the pattern dies. But eventually a pattern or several patterns must have occurred that, like the furnace in the star, just found life and wouldn't stop. Again it's a very primitive life but it's a chain of chemical reactions looped together that balance each other and become self sustaining. 
I believe this would have happened away from earth, most likely inside a meteor. There it would be sufficiently protected from the elements of space but still bombarded with radiation. The radiation providing the energy to fuel the chemical reactions taking place inside. Over billions of years the life inside would have evolved dramatically. The original elements and chemical reactions being replaced by the waste products and new feedback loops(chemical reactions) evolved in their place. Newer more complex molecules and combinations of molecules could be produced and made available.

Now the question is, what were these elements?
At first I felt it should be viruses, because I feel they developed before cells were evolved to protect the DNA in the nucleus. Before that I wondered whether DNA or RNA was actually its own lifeform and viruses were simply forms of life that chose not to form their own protective cell wall. But now I'm not sure that DNA was first. Maybe life forms began but kept dying because they had no efficient mechanism for reproducing. DNA and RNA may have come along much later as an efficient means of storing the information to create life. I say this because I wonder where the cell wall came from along with mitochondria, organelles and everything else.

Where did it all come from? However I've just realised it could be its own answer.
All these chemical reactions could have occurred in a liquid inside a meteor. The cell organs could all have developed separately at first through basic chemical reactions as previously explained. They then benefit from each others presence and at some point find even greater strength by being encased in a cell wall and using DNA/RNA to store their data and replicate themselves.

All of this could occur in a meteor or on earth, that's beyond what I know. The point is simply that the constant supply of energy to fuel the chemical processes is what lead to all this. The constant change ensured processes that didn't end in some kind of loop died out. Those that did, flourished and encouraged further evolution of the elements available for life and the processes by which energy exchange could be created. So it became a self fulfilling cycle.

The original forms of life either adapted or died due to the new environment they created. That seems to me to be the essential fact of life. It's not always the species causing its own extinction, a meteor crashing into a planet breaking open its core would change the gases and elements available to the life forms and the energy that they're exposed to. Some life forms would die, others would manage to adapt and survive. In my view one or more of these meteors crashed into earth and delivered life forms with chemical reactions that ultimately changed the envrionment and atmosphere of this planet into what it is now.

We may find that these original life forms have all died out, or they may exist among us. This may even be where the cell wall became important. As a basic protection from the outside world. When I watch videos of life inside a cell it very much feels like a walled city with all inhabitants thriving on the inside, well protected from the dangers outside. Each organelle within the cell seems just like an inhabitant of a city with their own role to play, each contributing to the overall balance and productivity.

Anywho, I feel I've explained the basis of how I feel life may have begun. It may have taken a different route but I feel that the process involves energy sustaining repeated chemical processes. As life evolves it begins to actively search out energy which leads to predator and prey and food chains. Balance is constantly being sought because new life can be created on the waste of others but any balance that is achieved can be upset by any number of events. Death occurs when the patterns of life that produce energy exchange stop. We see this when the sun is blocked by a meteor crashing to earth and creating a huge dust cloud, or when all the food an organism uses for fuel gets used up.

It explains for me why crocodiles have hardly changed since dinosaur times. Essentially because they're so efficient with energy they feel no pressure to change, yet mammals who are so wasteful of energy feel constant pressure to change.

So if you feel I've missed something that's glaringly obvious, or just don't agree with what I'm saying then please post a comment. I've just put down what makes sense to me. I can't claim it's correct it just seems to explain so much to me.

I also like that it's essentially very simple. It says that the origin of life is in energy. Life exists when energy is being changed to a different form in a pattern that repeats itself over time. The presence of life inevitably changes the environment around it. Often to the point where energy giving processes become difficult. This creates pressure to evolve. Either existing or new organisms will find life and convert energy from the new environment that is created. This in itself is a repeatable process. one which must have failed on all planets except our own. Unfortunately it suggests that life has begun and died all around our universe. It may still thrive elsewhere, but to our knowledge this is still the only planet where the patterns of life have yet to stop running.

edit 12th november 2010
in Horizontal and vertical: the evolution of evolution I think they're arriving at some of the conclusions I have and in my post evolution is everywhere I've added to this concept further. 
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