A common claim made to atheists by many religious believers is that life does not come from non-living matter. We have only observed living things arising from other living things, they argue, and no one has yet discovered life emerging from, say, a jar of peanut butter. The irony behind such statements is that Jews, Muslims, and Christians all believe God created life from non-life (humans come from dust according to Jews and Christians, clay for Muslims), so they do not actually object to life coming from non-living matter, they only object to it happening without the intervention of a deity. While the objection is rooted in special pleading, it does raise a question worth considering. Are scientists and atheists really at a loss here, or is there evidence that life can arise from non-life?

I. The Origin of Life

In exploring the emergence of life, we should first strive to understand what life is, and unfortunately this continues to be no small problem for scientists, philosophers, and religionists alike. The layperson often thinks of life and non-life as a distinction between a human and a rock, as one example, yet this does not even begin to grasp the wide spectrum of what might fall under a definition for life. As atheist writer Austin Cline asks, "[w]hat sort of definition would include viruses, but not fire... sterile mules, but not self-replicating crystals?" [1] Life is a more ambiguous concept than we think, not because it is some mystical or magical force, but because the line between life and non-life is very unclear at times.

Abiogenesis is the name for the field of science that studies how life formed on Earth, specifically from non-living matter. We do have some basic understanding of life, that it reproduces, grows, metabolizes, stores information, and so on. Whether we're talking about a great whale or bacteria, these signs of life generally apply. Science tells us that all living things are made up of cells, and proteins are a key component in the formation and function of cells. Proteins are linear chains of molecules called amino acids, and as such, amino acids are the 'building blocks' for life. Because molecules are inorganic themselves, or not living, to show that they can form under natural circumstances would be to show that it is indeed possible for life to come from non-life. By "natural circumstances", I mean conditions that are characteristic of the natural world, as opposed to conditions limited to human design, i.e. a reliance on computer technology.

The 1953 Miller-Urey experiment was one of the first attempts to synthesize amino acids from a model of the earth's early atmosphere. Combining water, methane, ammonia, and hydrogen in a closed system of tubes and flasks connected in a loop, liquid water was heated to produce vapor, while electrodes simulated lightning. After a week of continuous cycles, the experiment yielded several amino acids and organic compounds [2]. Since its publication, many creationists have challenged the significance of Miller-Urey, with most objections centering around the simulation of Earth's early atmosphere, and the fact that the experiment produced racemic amino acids, which are not common in nature.

A racemic mixture has equal amounts of left-handed (denoted with an L) and right-handed (denoted with a D) enantiomers. Because L-enantiomers are dominant among amino acids in nature, some contest that Miller-Urey produced results that are unnatural. However, subsequent findings have demonstrated that a racemic mixture could be put off balance by the crystallization of certain racemic amino acids that leads to a more natural enantiomeric excess [3], or by the bombardment of meteorites that can introduce this excess [4]. Other experiments also support the early atmosphere proposed by Miller-Urey [5], suffice it to say that those who downplay the importance of this landmark experiment have raised objections that are already answered by additional discoveries.

Yet none of this really need be said, because even the creation of racemic amino acids definitively disproves the claim that life cannot come from non-life. All amino acids, racemic or not, are organic compounds, and thus we have inorganic chemical compounds like methane, ammonia, hydrogen, and water, producing organic compounds - the building blocks of life - in the Miller-Urey experiment. We need not mix around some chemicals in a vat and pull out a mouse to show that life can come from non-life, we only need to show that the formation of the building blocks of life is possible. It is certainly a fallacy to say that unless one can demonstrate the exact process by which life formed, it could not have occurred naturally. Who knows how many various ways life could have arisen, unknown to us? It is an argument from ignorance to conclude that 'because I see no way that life could have come from non-life, it did not happen'. There may not yet be a full step by step explanation of how the first single-celled organism developed from non-living matter, but this does not make abiogenesis impossible or even unlikely, it only means that further study is needed.

II. The Probability of Life

Life from non-life may be possible, but is it probable? Creationists and intelligent design advocates are fond of coughing up statistics for the improbability of abiogenesis and evolution, while pretending that their alternative of sudden and static creation by an invisible, eternal, immaterial, and all-powerful being is a more plausible explanation for how life originated. Famed astronomer Fred Hoyle is frequently cited giving a figure of 10^40,000 for the probability of life arising from non-life. In his book, Evolution from Space, he calculates the figure:

Statistics like these often rely on inaccurate understandings of evolution and abiogenesis, and this is precisely the problem with Hoyle's astronomically large figure. Hoyle fails to grasp that natural selection is not a random process, as it selects for or against specific traits, making it the opposite of random chance. This alone spells the collapse of his entire argument, but he also makes the assumption that early organisms had two thousand enzymes which needed to be assembled all at once. Evolution tells us that complexity is a gradual process though, which means that the earliest organisms likely did not have two thousand enzymes, nor would they all necessarily have to have been assembled in one brief instant. Hoyle's probability calculation is built on an ignorance of natural selection and two assumptions that misunderstand how evolution works in general.

Large numbers may appear improbable to us, but we think on a very short timespan in relation to the age of the earth and the universe, and it's worth remembering that evolution has a timeframe of about 13 billion years it's been operating in. With a systematic method of selection and such a long period to work with, the chance of life forming from non-life is not nearly as impossibly small as creationists claim. All we need is one abiogenesis event in 13 billion years, and as research continues we are finding this to be more and more probable, even under a variety of different circumstances [7].

III. Is Abiogenesis Irrational?

Creationists sometimes claim that abiogenesis is not just undemonstrated and improbable, but also irrational. They often conflate it with spontaneous generation, a defunct theory supplanted by abiogenesis which argued that life arises instantly and randomly from non-life. As just shown, however, this is the opposite of abiogenesis, which is a process directed by evolution, going through various stages of life, and occurring gradually, over billions of years. Spontaneous generation was thought to be more commonplace too, whereas abiogenesis is considered one single event.

Is it irrational to accept abiogenesis, since no one has observed it thus far? In discussing the evidence for a god, apologists like William Lane Craig enjoy reciting an old mantra: 'absence of evidence is not evidence of absence'. In his debate with Peter Slezak, Craig explains that this mantra does not hold sway if we should expect to find evidence which we are not finding. Although this is devastating to the idea of an interventionist god (yet Craig does not realize it), there are good reasons for why abiogenesis has not been directly observed. The timespan of gradual evolution is one reason, in addition to the difficulty of finding intermediate stages when pre-biotic molecules leave no fossils, as well as the fact that if abiogenesis was one event some billions of years ago, it could not have been observed when human observers had not yet evolved!

Abiogenesis may not yet be a fact of science proven beyond all reasonable doubt, but this does not mean belief in a naturalistic origin of life is unjustified. As Bertrand Russell and other atheists have pointed out, the explanations offered by science always tend to supplant supernatural alternatives, and in the centuries of scientific study, no supernatural explanation has come to supplant a scientific one. Science works, naturalistic explanations are its business, and business is good. Considering that abiogenesis has only really been a field of study in the last sixty years, the developments and discoveries we have are fairly impressive for such a recent discipline.

But why should life come from non-life anyway? It seems so counter-intuitive to many, but much of science is. Even outside of science, intuition has been shown to have a not-so-reliable track record, and many well-established facts of the scientific world would not have been stumbled upon if we had simply allowed intuition (or scripture) to guide us. We would at first think that of a bowling ball and feather dropped from the same height, the heavier object would hit the ground first, and yet the discoveries of science have proven otherwise. We would at first think that the earth is stationary and the planets, moon, and sun all rotate around us, and yet science has proven otherwise. To object that abiogenesis is counter-intuitive is indicative of nothing but one's own inability to wrap his/her brain around it.

Miller-Urey and the experiments that followed it provide us with plenty of evidence for the possibility of life emerging from non-life. An accurate understanding of natural selection, the timeframe for evolution, and the numerous models for life formation tell us that abiogenesis is also quite a probability, not merely a roll of the dice or a matter of chance. With these realizations, it is easy to see that life arising from non-life is not an irrational belief at all.

IV. The Untenable 'Alternative'

The supernatural alternative to abiogenesis that is put forward by creationists and intelligent design proponents is an explanation that truly explains nothing. Instead of answering the scientific question of 'how', it answers the theological question of 'who'. We are told that life has deliberate and directed design, that it shows evidence of a creator, and yet no theory on how this creator designed us is offered. There is no way to demonstrate that 'God said, "let there be life," and there was life,' because this is not a scientific explanation of how life happened, but a theological one of who made it happen. If you asked how I made a video game with a whole graphical world out of simple letters and numbers, and I responded, 'I designed it,' you would probably look at me strangely and repeat the question, because I did not actually give you an answer.

Creationists attack the naturalistic explanation for life's origins without providing an alternative, but it stands to reason that if a creator designed life, it must have done so by some method or process. To design something involves goals, functional requirements, specifications, components, testing, and so on. Even an artist that improvises a work has some ideas in mind about what medium they will use, how they can make use of it, and what they will need to make it happen. While according to the bible, God just spoke and plant and animal life came magically into being, we know there would have to be more behind the scenes, because there is more beneath the surface - an entire world of microbiological structures. These smaller components all have tasks they carry out that are integral to the whole. In other words, even if there is a creator, there is a perfectly valid 'how' question that remains to be answered.

Religious believers will scoff that, 'God works in mysterious ways,' and so the how will never be fully answered, but the point here is that intelligent design creationism gets us no closer to understanding life's origins. It is even a step behind abiogenesis, because it addresses a different question, and the address that it gives is also problematic. Inserting a god or designer where science has not yet reached a solid conclusion does not resolve what it intends, nor does it even answer the 'who' question in any meaningful sense, because an appearance of design would still not tell us if the designer is a deistic god, a group of polytheistic gods, any of the gods of monotheism, or perhaps something else altogether. For more on the problems of the design argument, see my article on The Teleological (Design) Argument.

There is no rational nor defensible reason for proposing the involvement of a designer or god in the formation of life. As just shown, it does nothing to resolve the question of how life began, and it is merely an extraneous assertion proffered by those who are motivated by their personal faith, not by evidence. Abiogenesis, on the other hand, life from non-life, is backed by experimental evidence, numerous logical theories on life formation, a probability that fits well within the parameters of evolution in an old universe, rational consistency, and much more, with no dogma and no faith necessary. As science continues to advance, we will only see life from non-life gain more and more of a solid foundation.

1. Cline, A. Abiogenesis, the Nature of Life. About.com. Retrieved Nov. 29, 2010.
2. Anonymous. Miller-Urey experiment. Wikipedia. Retrieved Nov. 29, 2010.
3. Kojo et al. (2004) Racemic D,L-asparagine causes enantiomeric excess... Chemical Communications. Retrieved Nov. 29, 2010.
4. Cronin & Pizzarello. (1997) Enantiomeric excesses in meteoritic amino acids. Science. Retrieved Nov. 29, 2010.
5. Fitzpatrick, T. (2005) Calculations favor reducing atmosphere for early earth. Washington University Online. Retrieved Nov. 29, 2010.
6. Hoyle, F. (1984) Evolution from Space. p.24.
7. Anonymous. Current Models for Abiogenesis. Wikipedia. Retrieved Nov. 29, 2010.