Every protein in your body is built from amino acids of one handedness. Ordinary chemistry has no reason on earth to prefer one hand over the other — and that gap is older, deeper, and far less discussed than the fossil arguments.
Hold your hands up in front of you, palms facing you. Same number of fingers. Same joints. Same proportions. Mirror images of each other — and no matter how you rotate them, you cannot lay one on top of the other and have them match. A left glove will not go on a right hand.
Molecules do that too. And the fact that life uses only one of the two options, across the board, in every organism anyone has ever examined, is one of the most concrete unsolved problems in origin-of-life chemistry. Most believers have never heard of it. It deserves a hearing, and it deserves an honest one.
What handedness means in chemistry
A carbon atom bonded to four different groups can be assembled two ways. The two versions contain identical atoms joined by identical bonds, but they are mirror images that cannot be superimposed. Chemists call them enantiomers, and the property is called chirality — from the Greek for hand. Louis Pasteur stumbled onto it in 1848, sorting two kinds of tartrate crystal under a lens and finding they bent polarized light in opposite directions.
Here is the part that matters for this discussion. In a chemically neutral environment, the two mirror forms are energetically identical. Same bond strengths. Same stability. Same everything. Nature, left to itself, has no preference — and that is not a gap in our knowledge, it is a consequence of how the bonds work.
So when you synthesize an amino acid in a flask by ordinary chemistry — the classic spark-and-gas experiments of the 1950s, or the standard synthetic routes — you get both hands in roughly equal amounts. A fifty-fifty mix. Chemists call that racemic. It is what indifference looks like.
Life is not indifferent
Now look at a living cell. The amino acids that make up its proteins are, with trivial exceptions, left-handed — what biochemists label L. The sugars in its DNA and RNA are right-handed — D-deoxyribose and D-ribose. One hand for the proteins, the other for the genetic backbone, held with remarkable consistency from bacteria to blue whales. Glycine, the simplest amino acid, has no mirror form at all, so it sits outside the question.
And this is not decorative. A protein works because it folds into a precise three-dimensional shape, and the shape depends on the chain’s residues all turning the same way. Drop a right-handed amino acid into a helix and you kink it. Build a protein from a random mix of hands and you do not get a slightly worse enzyme — you get a chain that will not reliably fold into anything that functions. The same goes for nucleic acids: a backbone of mixed sugars does not stack into a stable double helix.
So the requirement is not a preference. It is a prerequisite. Life needs a single convention, enforced system-wide, in a chemistry that supplies no reason to pick one.
The best naturalistic proposals — stated fairly
If you are going to use an argument, you have to be able to state the other side the way its own advocates would. Christians who caricature the science forfeit the right to be taken seriously about it. So here is the actual research, and some of it is genuinely clever.
- Starlight with a twist. Circularly polarized ultraviolet light in star-forming regions can destroy one mirror form slightly faster than the other. Amino acids recovered from meteorites — the Murchison meteorite most famously — do show small left-handed excesses in certain compounds, which is a real and interesting result.
- Chiral mineral surfaces. Certain crystal faces, such as the two forms of quartz, adsorb one enantiomer in preference to the other. A genuine laboratory effect.
- Amplification chemistry. This is the strongest piece. Some reactions take a tiny imbalance and run away with it. The Soai reaction is autocatalytic: a nearly undetectable excess of one hand multiplies itself into a large one. Attrition-driven crystal grinding can push a mixture almost entirely to one hand. And certain amino acids, when a near-racemic mixture is partly crystallized, leave a solution strongly enriched in one form.
- Physics itself. The weak nuclear force violates mirror symmetry, so some have proposed an intrinsic cosmic bias. The predicted effects are extraordinarily small.
None of that is fraud, and none of it should be waved away. Amplification in particular is a real answer to a real sub-question: granted a small bias, chemistry can sometimes magnify it.
What is still missing
Granting all of the above, three problems remain, and they are the reasons this is still an open question in the literature rather than a settled chapter.
One: the amplifiers are fussy. The showcase mechanisms work under controlled laboratory conditions — specific reagents, specific solvents, specific crystallization regimes, an experimenter holding the system steady. A shoreline or a hydrothermal vent is not a clean flask. Showing that an effect is chemically possible is not the same as showing it is probable in an uncontrolled environment, and that distinction is where most origin-of-life claims quietly live.
Two: the clock runs backwards. Chiral molecules do not stay pure. In warm water, amino acids racemize — they drift back toward the fifty-fifty mix on their own, which is exactly why measuring that drift is a dating technique in fossil shells. So any enrichment has to be produced faster than it decays, and then captured and used before it relaxes. Time is not on the mechanism’s side; time is the opposition.
Three, and this is the one worth sitting with: the hands are coordinated. Life did not simply pick a hand once. It runs left-handed amino acids and right-handed sugars together, in the same cells, in a system where the translation machinery, the ribosome, is itself built of the one and reads the other. A mechanism that explains a localized excess of one compound on one mineral surface has not begun to explain a matched, system-wide standard holding across two different molecular families and the machine that couples them.
Where the design inference actually comes in
Now be careful, because this is the point where Christians often overreach and hand the skeptic an easy win.
The argument is not “chemistry has not explained it, therefore God.” That is an argument from ignorance, and it loses ground every time a laboratory publishes. If someone demonstrates a robust prebiotic route to a coordinated, system-wide chirality, this particular argument is answered, and an honest Christian should say so. We are not invested in the gap. We are invested in the truth.
The design inference is comparative, not negative. It runs like this. We know of exactly one kind of cause that reliably imposes a single arbitrary convention across an entire system when the underlying physics is indifferent between the options: a mind choosing a standard. Thread direction on a bolt. Which side of the road to drive on. Which end of a byte comes first. In every case the physics permits both, the system requires one, and an agent picks.
Chirality in living things has that signature. Two options, physically equivalent. A system that cannot function on a mix. A convention held consistently across the whole of biology and coupled between molecular families. That is not what a law looks like, because a law would have a reason to prefer one hand. It looks like a choice, made once, and built to.
And notice how little this costs in the family arguments. Whether you read Genesis as six ordinary days or hold an older earth, this one does not depend on the age of anything. A brother who disagrees with you about the rock layers can stand on this with you.
You are carrying the evidence
Scripture never argues the way a chemistry paper argues. But it does claim that the made thing testifies about the One who made it, and that the testimony is clear enough to leave a man without a defense.
For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse. (KJV)
Romans 1:20
And David, who had no idea what a protein was, said something about his own body that reads strangely well next to a folded enzyme.
I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well. My substance was not hid from thee, when I was made in secret, and curiously wrought in the lowest parts of the earth. (KJV)
Psalm 139:14–15
Curiously wrought. The old word means intricately worked, embroidered, made by skilled hands. Every enzyme in you is a chain of left-handed links, folded into a shape specific enough to do one job, reading instructions written on a right-handed spine. You do not have to settle the chemistry to feel the weight of that. You are the argument, walking around.
But a conclusion is not a conversion
Here is where I will not let this end, because an argument can win and still leave a man exactly where he started.
Suppose you grant all of it. Suppose you agree that the handedness of life looks like a decision rather than an accident. You have arrived at a Designer with excellent taste in molecular standards, and you can hold that conclusion for forty years without it costing you one thing.
The God of Scripture did not stop at setting conventions. He came into the system He built, took a body made of the same left-handed proteins as yours, and died in it — for men who looked at the evidence and did not want Him. The handedness in your cells can tell you that Someone chose. It cannot tell you that He loves you. For that you have to go to a cross, and that is not a chemistry problem. That is an invitation, and it has your name on it.
Both hands were available. He made one. Then He opened both of His, and let them be nailed down.
Teaching the Word. Watching the Times.
— SmithForChrist