I propose that the ultimate origins of life on this planet will forever be impossible to fully explain. I propose that this impossibility is a consequence of the infinite intelligence of the creator of life: if a God of infinite intelligence created something, we will never be able to explain its origins by natural means. We may be able to hazard a guess, or propose a natural pathway, but upon closer inspection, such explanations will always be found to be unrealistic, unworkable or both. The reason for this is simple: you cannot explain something that cannot happen. It's impossible to explain the impossible. What's more, even if we accept Intelligent Design, we will still be unable to fully explain these things. We will not be able to decipher all of the engineering, physics, mathematics or chemistry that went into the actual planning of such systems. It will be as far above our level of intelligence as the ends of the universe are above our heads. This "Argument from Impossibility" is a necessary consequence of the chasm between an infinite mind and our limited human understandings. In short - God's ways are unfathomable.
I'll give an example:
All life utilizes amino acids for the production of proteins. Amino acids are a basic building block for all cellular life. But how do we explain the origins of this amino acid based system?
In 1953, Stanley L. Miller and Harold C. Urey, working at the University of Chicago, conducted an experiment that showed that amino acids could be formed by shooting electricity through a mixture of methane, ammonia, hydrogen, and water. This experiment was hailed by many to be evidence that living things can arise from non-living elements. Unfortunately that's not how amino acids are formed in real living cells.
The mild conditions and aqueous solution within real cells are not conducive to rapid chemical reactions like those required in the Miller/Urey experiments, therefore a catalyst of some type is needed. Luckily enzymes fit the bill. Enzymes are structurally complex molecules, often highly specific, that act as catalysts for biochemical reactions within living cells. An enzyme generally catalyzes only one type of reaction.
In E. coli, (a "simple" unicellular lifeform), the amino acids aspartic acid, asparagine, lysine, threonine, isoleucine, and methionine are synthesized from the compound oxaloacetate via a series of biochemical steps - each of which is catalyzed by a specific type of enzyme. To get from oxaloacetate to aspartic acid only takes one step, asparagine requires two steps, lysine requires nine, threonine five steps, isoleucine ten, and methionine seven. This biochemical pathway is what's known as a branching pathway. This means that some of these steps are shared, therefore there are a total of twenty steps and enzymes - not thirty-four.
Here's the pathway:
Aspartic Acid* (2) Asparagine*
Aspartic β-semialdehyde (5)(6)(7)(8)(9) Meso-diaminopimelate (10) Lysine*
Homoserine (12)(13)(14) Methionine*
Threonine* (16)(17)(18)(19)(20) Isoleucine*
Amino acids are marked with an asterisk *
Each number in parentheses ( ) represents a discrete biochemical step catalyzed by a specific enzyme.
So the challenge is to explain how the current amino acid synthesis system in E. coli originated via natural mechanisms. How did each of the twenty enzymes come to be? How did each of the twenty steps in the biochemical pathway come together in the correct order to form these essential amino acids? What was the immediate precursor to the current system? What were all the intermediate steps? Remember that this explanation must account for every enzyme and every step. Also, the production of each enzyme is regulated by a hierarchy of gene expression controls. That means that individual enzymes are only produced in the amounts needed for the processes they perform. If enzymes were unregulated you would either have too many of them, wasting both energy and resources, and causing a chemical imbalance or even cell rupture, or you would have too few, which would halt amino acid synthesis. The pathway itself is also regulated. Certain substances act as chemical switches; activating or deactivating key enzymes within the pathway. This regulation generally happens at the beginning of the pathway or at key branch points (thus ensuring, again, that energy and resources are not wasted). This regulation ensures that only the necessary amounts of amino acids are produced. How did each layer of this multi-leveled regulation come about? To further complicate matters let me add here that enzymes are proteins, and proteins are made from (you guessed it) amino acids! So enzymes are required to make amino acids and amino acids are required to make enzymes. A divine catch-22!
I predict then that no one will be able to answer this challenge with any detail; even though this is one of the simplest systems, in one of the simplest single-celled lifeforms, on the planet. The synthesis of amino acids is a basic foundational system; it is not a highly complex, multicellular system such as the vision system, the circulatory system, photosynthesis, or the human brain. Those systems are orders of magnitude more complex than this one. Therefore this, and countless other origins, will forever remain an "Impossibility".