Glycylglycine is the most boring molecule in this entire subject. Two glycines stuck together. Glycine is the simplest amino acid there is — its whole side chain is one hydrogen atom, which is to say it barely has one. Join two end to end and you get a compound weighing 132 grams per mole that sits on a shelf in every biochemistry lab on Earth, where its job is stopping the pH of a solution from wandering.
Superman can move planets.
The answer is that neither of them is from here.
The provable alien
Superman’s origin is the most famous in fiction. Krypton dies, a rocket leaves, a baby lands in Kansas. He is an extraterrestrial raised as a local, and the whole character runs on that tension.
Glycine has the same story, except it happened.
The Murchison meteorite fell in Australia in 1969. It has since yielded more than seventy amino acids — glycine among them. That they came from space rather than from contamination on the ground isn’t an assumption: the carbon isotope ratios are wrong for Earth, and the amino acids arrive as near-even mixtures of left- and right-handed forms, where terrestrial biology overwhelmingly favours one hand. The chemistry carries a return address.
NASA’s Stardust probe flew through the tail of comet 81P/Wild 2, caught the dust, and brought it back to Earth in 2006. In 2009 the analysis confirmed glycine in the sample — again isotope-verified, again not from here.
Rosetta went further. It didn’t collect a sample and come home; it flew alongside comet 67P/Churyumov-Gerasimenko for two years, sniffing the gas streaming off it. In 2016 its mass spectrometer reported glycine in the coma, along with phosphorus. Both are components of what you're made of, measured in the exhaust of a comet, 500 million kilometres away.
Glycine is currently the only amino acid confirmed in a comet. It is also the one on the left-hand side of glycylglycine, and the one on the right.
The part that’s better than the trivia
Detecting amino acids in space is a known headline. The next step is the one that makes glycylglycine specifically interesting, and it's more recent.
Amino acids are beads. A peptide is beads on a string, and the string is the peptide bond — the thing Emil Fischer spent his career learning to tie. The reasonable assumption for a long time was that space gives you loose beads and you need a planet, liquid water and a great deal of luck to get a chain.
In 2022 a team working on interstellar dust chemistry demonstrated a route by which peptide chains can assemble on the surface of cold dust grains, in conditions like those inside a dark molecular cloud, before a star has even formed. Not amino acids waiting to be joined. Joined.
Which means the simplest possible product of that process — glycine bonded to glycine — is not a thing humans invented in a flask in Berlin in 1901.
It is a thing the galaxy has been doing, quietly, on dust, for several billion years longer than Earth has existed.
Fischer wasn’t inventing. He was catching up.
Here’s what makes this genuinely funny rather than just neat.
In 1901, Emil Fischer and Ernest Fourneau joined two glycines and produced the first peptide anyone had deliberately synthesised. Fischer coined the word peptide shortly after, from the Greek peptos, digested. He named the entire category by making its first member. He was one of the great chemists of his age and it was a landmark result — by 1907 he had built an eighteen-residue chain, a feat of stubbornness that stood for decades.
And the molecule he made to open the field was one that forms by itself on frozen dust between the stars.
Every peptide in every vial sold anywhere today descends from that flask. BPC-157, tirzepatide, the whole catalogue. Same chemistry, better equipment. But the founding act wasn’t creation. It was the first time anyone on this planet managed to do on purpose what a molecular cloud does by accident.
Superman gets the same treatment, incidentally. He didn’t arrive fully formed either — in 1938 he couldn’t fly, just jumped. The flight, the vision, the freezing breath all got added later by people working out what the thing they'd imported was capable of.
Making them was never the hard part
Fischer’s eighteen-residue chain cost him years. In 1963 Bruce Merrifield worked out how to build a peptide while anchoring one end to a resin bead, washing reagents away between steps instead of purifying at every stage. It collapsed the labour by orders of magnitude and won him a Nobel Prize.
Today a machine does it. You type a sequence, you come back in the morning, and there it is.
So line up the timeline. Interstellar dust has been making peptide bonds for billions of years. Emil Fischer managed it in 1901. Merrifield automated it in 1963. A benchtop synthesiser will make you a novel thirty-residue peptide overnight for a modest invoice.
Producing a peptide is something a cold dust grain can do unattended. Finding out whether it does anything in a human being still takes years and millions of dollars.
That asymmetry is the entire research-peptide market. One side of the problem was solved by physics before Earth existed and automated sixty years ago. The other side has never been automated, can’t be, and gets more expensive every year.
So the catalogue fills with compounds that exist and haven’t been tested, because existing is free and being tested isn’t.
Insulin, the GLP-1s, oxytocin, vasopressin, octreotide, leuprolide and the rest — 125 years of work, against many hundreds of peptides sold online with no human trials behind them at all.
“But peptide drugs obviously work”
They do, and the successes are spectacular. This is the part a lazily sceptical article would skip.
Insulin is a peptide, and it turned a uniformly fatal diagnosis into a manageable condition. The GLP-1 agonists are peptides, and whatever you think of how they're marketed, the trial data is enormous and the effects are real. Oxytocin, vasopressin, octreotide, leuprolide, teriparatide — all peptides, all approved, all doing measurable work in patients today.
The category isn’t a fraud. Peptides are one of the most productive drug classes in medicine.
Which is exactly what makes it hard to think about clearly. If peptides didn't work, the question would be easy. The problem is that some peptides work extraordinarily well, and that fact gets borrowed, constantly, by compounds that have never been near a trial.
Insulin's record is not evidence about BPC-157. They share a type of chemical bond, which is about as informative as noting that aspirin and cyanide are both small molecules.
Both from space. Only one of them checkable.
Superman’s alien origin is a story, and it's a good one, and it cannot be verified because there is nothing to verify.
Glycine’s alien origin is a measurement. Someone flew a probe through a comet’s tail, brought the dust home, ran the isotope ratios, and established that this specific carbon did not form on this planet. The claim is extraordinary and it is documented, which is the only reason anyone believes it.
That's the whole difference, and it's the difference this site exists for.
The universe has been assembling peptides on frozen dust since before the sun lit. We’ve been doing it since 1901, and doing it trivially since 1963. Neither of those facts tells you anything at all about whether the compound in front of you does what someone says it does.
We can prove an amino acid came from a comet. We still can’t tell you whether most of what’s in the catalogue does anything, because nobody has looked.
An interstellar dust grain has been making glycylglycine for billions of years without being asked and without a certificate.
It doesn’t need one. It isn’t selling anything.