The fine-tuning argument shows the universe was calibrated for life. But there is a separate, even harder question: once a universe with the right constants exists, how did non-living chemicals become the first living cell? Rice University chemist James Tour - one of the world's leading synthetic organic chemists - argues that the honest answer is: nobody knows.
The origin of life - sometimes called "abiogenesis" or "chemical evolution" - is the question of how the first living cell arose from non-living chemistry. It is important to distinguish this from biological evolution. Darwin's theory of evolution by natural selection explains how existing life diversifies. It does not explain - and Darwin himself acknowledged it does not explain - how life began in the first place.
This is not a minor gap. Without the first cell, there is nothing for natural selection to act upon. The origin of life is the foundation upon which all subsequent biology rests - and it remains, by any honest assessment, an unsolved problem in science.
James Tour, T.T. and W.F. Chao Professor of Chemistry at Rice University, has over 700 peer-reviewed publications and several hundred patents. He is one of the most cited chemists in the world. His expertise is in building complex molecules from scratch - which gives him a unique perspective on what would be required for life to assemble itself.
Life requires four classes of complex molecules: amino acids (for proteins), nucleotides (for DNA and RNA), carbohydrates (sugars), and lipids (for cell membranes). Tour has identified five fundamental problems that origin-of-life research has not solved:
In 2023, Tour issued a public 60-day challenge to ten leading origin-of-life researchers: demonstrate that any one of these five problems has been solved - even under unrealistically favorable conditions. He allowed them to assume purified starting materials, correct handedness, and even let a three-member panel chosen from among the ten experts judge the results. The deadline passed without any researcher attempting to answer even one challenge. jmtour.com
One of the deepest chemical obstacles deserves special attention. Most biological molecules exhibit chirality - they come in "left-handed" and "right-handed" forms, like mirror images of each other. Life uses almost exclusively left-handed amino acids and right-handed sugars. A single wrong-handed molecule in a protein chain can destroy its function.
Every known prebiotic synthesis produces a 50/50 mixture of left- and right-handed molecules. There is no demonstrated prebiotic mechanism for achieving the near-100% purity that life requires. Tour has pointed out that this problem alone - before you even get to sequencing, folding, or assembly - is sufficient to stop abiogenesis in its tracks.
In 1953, Stanley Miller and Harold Urey famously produced amino acids by passing electrical sparks through a mixture of gases meant to simulate the early Earth's atmosphere. This experiment is routinely cited in textbooks as evidence that life's building blocks form easily under natural conditions.
What the textbooks often omit:
It is important to be precise about Tour's position:
Tour writes: "Those who think scientists understand the issues of prebiotic chemistry are wholly misinformed. Nobody understands them. Maybe one day we will. But that day is far from today." He adds: "Life based upon amino acids, nucleotides, saccharides and lipids is an anomaly. Life should not exist anywhere in our universe. Yet we are led to believe that 3.8 billion years ago the requisite compounds could be found in some cave, or undersea vent, and somehow they assembled themselves into the first cell."
"Given enough time, even improbable chemistry becomes inevitable. Life had billions of years."
Time is necessary but not sufficient. The problem is not just improbability - it is that the required chemistry works against life. In water, biological molecules tend to decompose, not assemble. Longer time periods mean more decomposition, not more progress. As Tour emphasizes, any amino acid chain that formed on the early Earth would have hydrolyzed (broken apart) long before it could find its way into a proto-cell. Time is the enemy, not the friend, of prebiotic chemistry.
"Tour is a nanotechnologist, not an origin-of-life researcher. He's outside his field."
Origin-of-life research is organic chemistry - it asks how complex organic molecules formed and assembled. Tour is one of the world's foremost experts in exactly that: synthesizing complex molecules from scratch. His expertise in building the very types of molecules that life requires gives him direct, relevant authority on whether proposed prebiotic pathways are chemically plausible. The question is not who is making the argument, but whether the chemistry is correct.
"Science just hasn't figured it out yet. Give it time."
This is a fair point - science is ongoing. But Tour's argument is not "we'll never figure it out." His argument is: (1) the current state of knowledge is far more primitive than the public has been told, (2) the more we learn about cellular complexity, the harder the problem becomes (the goalposts keep moving further away, not closer), and (3) the honest conclusion right now is that unguided chemistry has not been demonstrated to produce life and the gap is widening, not closing.
Why does James Tour argue that the Miller-Urey experiment is insufficient to explain the origin of life?
The origin of life remains one of the deepest unsolved problems in all of science. James Tour - one of the world's top synthetic chemists - has demonstrated that no current origin-of-life model has solved even one of five fundamental chemical problems. The Miller-Urey experiment is routinely overstated. The chirality problem alone is a showstopper. And the more we learn about cellular complexity, the wider the gap becomes between what unguided chemistry can produce and what even the simplest life requires.