Abiogenesis is the most likely explanation for life.

One widely accepted scenario for Abiogenesis is the gradual formation of life from simple chemicals leading to proteins (metabolism first) or RNA, self-replicating polymers (often assumed to be RNA) and simple cells called protocells leading to complex cells with a metabolism where evolution is in full swing. It is the only credible scientific theory for life origins It is defined simply as, “the supposed spontaneous origination of living organisms directly from lifeless matter [1].” Note the definition is very broad and encompasses any credible natural/scientific explanation and there are many models for the formation of life [8]. The only other alternative is Intelligent Design, which has no explanatory power. It offers no mechanism, proofs, predictive power, falsifiability or new information. It is not an explanation. RNA world model, the gradual formation of complex life in stages: 1) The basic building blocks of proteins form naturally Miller–Urey experiment famously demonstrated that 20 amino acids (out of 22) can spontaneously form [3]. This is important since these are the building blocks of complex proteins that, along with RNA/DNA form cell structures. Scientists have now worked with a variety of environments to produce amino acids and we know that at least 15 have been found in crashed meteorites, some with only a left handed chirality as seen in proteins [5]. 2) Early cell core structures, RNA/DNA, and nucleotide formation Scientists have now proven chemical pathways that form two of the four nucleotides that are the building blocks of RNA and also to form shorter RNA strands naturally. These were likely the core structure in the first cells [6]. RNA along with protein hybrids can form proteins from amino acids, catalyze important reactions in cells along with DNA formation and perform many other tasks important for life [7]. Recent studies have shown promise that DNA may even have formed first [9]. 3) Self-replicating polymers, usually assumed to be RNA, ‘evolve’ In a large pool of random RNA self-replicating versions can arise and leading to potential ‘evolution’ as mutations made in self-replication lead to changes and respond to selection pressures improving efficiency [3]. The most efficient self-replicators winning the race and mutations leading to new polymerases and ligases that can assist in forming RNA/DNA and proteins. 4)Early cells (protocells) and replication Early cells were likely small RNA strands enclosed in fatty acid membranes that have been shown to form naturally and can allow nucleotides to cross the membrane [6]. Experiments have shown that nucleotides naturally bond to single RNA strands by base pairing in colder environments eventually forming the twisted double helix we are all familiar with. In hotter environments, such as thermal vents, the strands can separate. Natural circulation cools the environment where natural base pairing would then create a replicated RNA strand and this is a potential early path for RNA replication leading again to a process of natural selection. Experiments have shown that primitive vesicle membranes can both grow and divide potentially to protocell replication. 5) Increasing complexity of cells and the development of a metabolism As RNA strands replicate they inevitably mutate and change. These could have formed before cells and have been shown to improve replication in successive generations and can form ribosomes which are folded RNA molecules that can take on such tasks catalyzing RNA reproduction, synthesizing nutrients and strengthening membrane walls. At this point Evolution takes over and primitive cells would respond to selection pressures. Out of the polymers that can form many, called ligases and polymerases, can also catalyze DNA, RNA and protein formation, which are the basic building blocks of life[4]. In a 220 nucleotide RNA strand there are 2.5x 10^112 efficient ligases and that’s just those we are aware of. - I barely scratched the surface with our 5,000 character limit but I have been able to show that there is evidence and many plausible scenarios for the earliest cells to form. This is the explanation that the best method for identifying truth, the scientific method, has produced. It is the only credible explanation for life. God did it is not an explanation. [1] http://www.merriam-webster.com... [2] http://www.imachination.net... [3] http://www.talkorigins.org... [4] http://www.talkorigins.org... [5] http://en.wikipedia.org... [6] http://www.mcb.ucdavis.edu... [7] http://en.wikipedia.org... [8] http://www.livescience.com... [9] http://www.dailygalaxy.com...