OR 4 and 20 Backbones, baked into an 'I', OR Descent from What? The greatest mystery in biology now is how did life begin. Here is my hypothesis about its origin. [In science hypothesis = maybe, theory = sure thing]. I've been working on these ideas for about 30 years. This essay is very condensed and somewhat technical for many readers, so feel free to skip it. But for those who stay, it may be one of the most exciting adventures in science. We begin with what we know:
1. Darwinian evolution - descent with modification - seems to work in prebiotic (pre-life) processes. That means that certain chemicals will survive because they are better adapted to the environment. 2. Basic building blocks of life, amino acids , nucleic acids, etc.; have been recreated in lab experiments (Miller, Oro, etc.). 3. The 'RNA world' idea seems highly plausible (Gilbert).
At first versatile RNA was both codebook and catalyst. Later DNA was the codebook for life (Crick, Watson) and proteins became the enzymes,. Thus RNA was at first both the chicken and the egg - replication through the code, and metabolism through enzymes!
But there is a lot of unknown area between building blocks and RNA world that no one has filled in. And no one has evolved any overriding hypothesis that makes any sense why life happened. The best 2 arguments - and they aren't very good at all - are a. It flew in from space (panspermia) or b. It had to happen over all those millions of years (fluke hypothesis). Here is my idea:
Life is an energy moderating chemical system. It began as a reaction to - and driven by - a hot/cold cycle set up by the sun. Specifically a sun/UV/hot/dry then night/cool/wet cycle [And most likely a hydrophobic - hydrophilic split too] Life did not have an independent origin but a dependent one that was a reaction to what went before it. Example thunder only follows lightning. It can't exist outside of lightning.
Specifically: During a narrow window of opportunity on earth ( 4.2-3.8 billion years ago) when the earth was cooling, the water vapor was turning to rain, the oceans were forming, the sun was shining through the atmosphere for the first time, the atmosphere had a lot of CO2 and water, the temperature range was near 70C - 120 C (good for hydrogen bond chemistry) , and the primordial sea was full of basic building blocks (monomers); the heat cycle 'selected' those chemicals that didn't burn up in the high heat. Heat is the universal killer of all life.
In cold temperatures, chemicals just shut down or hibernates till the heat rises again. The two most notable strategies for surviving this heat cycle were coincidentally the two terms we use to define what life is - metabolism and replication. And I add that they are two sides of the same coin - two ways to keep from burning up!
The biomolecules that are truly fundamental for life are amazingly - shockingly few. They involve 20 amino acids, 5 nucleobases, 2 sugars, glycerol, an amino alcohol (choline) and a fatty acid (palmitic acid). Or in even simpler terms - assorted bases that react with assorted amino acids plus some odds and ends to help the process. AND the bulk of the important chemical reactions between the bases and the amino acids is amazingly - shockingly - mostly about hydrogen bonding - a type of very weak chemical bonds that are highly susceptible to a heat cycle (denaturing and annealing). In even more simple (and somewhat simplistic) terms the bases are components of paired nucleotide strands of code (the genome). When they separate completely to make copies (all hydrogen bonds are broken), its replication. When only part of the pair separates and is read to make proteins (some hydrogen bonds are broken), it is protein synthesis or metabolism. Replication and metabolism are all very similar, and very much connected.
Life then is 1. A specific environmental heat cycle that produces the basic building blocks and through heating and cooling makes many variations of these building blocks and selects those most favorable. 2 As earth cooled the chemical system formed by these selected building blocks, took over for the external heat cycle to maintain its optimum state where its enzymes are most productive. As replication continued, the best-adapted variants were selected. Note that excluding a few oddball species, ALL life that has ever existed, exists between 0C - 100C the limits of liquid water. Once life set up a cell membrane [that too is produced in a heat cycle - (Fox)], we have 4 options, or 4 ways for the cell to moderate energy: 1. Take in more,
2. Don't take in more - block it out, 3. Hold in more, 4. Don't hold in more - excrete it out. I contend that these 4 options have through Darwinian evolution, evolved to every aspect of every living thing, that they also relate to Karen Horney's groundbreaking psychological work on 3 types of human social behavior, that resolving 4 option problems in human behavior will resolve a vast layer of physical and psychological problems, and that using a specific therapy that I have devised may accomplish this.
Also I suggest the following model to show how fast life evolves: As adaptation fitness increases - directional and diversifying selection decreases and stabilizing selection increases - and vice versa. This also supports the idea of punctuated equilibrium (Gould, Eldredge) and my Slope and Plateau model. And that's just the outline!
Talk Amongst Yourselves or 4 word lingo that aliens will know.
In my hypothesis I suggest the concept of the 4 options - 4 ways for Darwinian evolution. And because I see them as universal to all, I think they would form the basis for a 4-word language that we and all calling aliens could understand. Let's review what they were: #1 Don't have - want (take in) #2 Don't have - don't want (block out) #3 Have - want (keep in) #4 Have - but don't want (excrete out). That's our vocabulary - 4 words we'll call 1,2,3 and 4. Begin with #3. Hold something you like in your hand. Explain to alien that this = 3. Put it on a table far away and express longing for it = 1. Hold something that smells bad = 4. Place it on a table and explain that you don't want to go near it = 2. See how it works? Those 4 phrases or word concepts really cover a lot of ground! They are a sort of sign language based on universal life biology. Maybe some day we'll be able to try it? [Alien note: at this time, we are looking for radio waves from the skies at the low end of the electromagnetic spectrum. I tend to think that aliens are more likely to send wave/messages nearer UV wavelength - which is a key ingredient to life's heat cycle. We may be looking in the wrong frequency!]
These authors are recommended or were quoted or info from them was used to write these essays: M. Olomucki, C. Wills and J. Bada, Lynn Margulis, Stephen J. Gould, James Lovelock, William K. Hartmann, Karen Horney, George O. Abell, Clifford D. Simak, Neil A Campbell, and all the posters at Sci.bio.evolution newsgroup.