The Book of PeptidesThe Book of Peptidesthe "love hormone"
1906 (Dale's discovery of the uterine effect); 1952-1953 (isolation, sequencing, first synthesis); 1955 (Nobel Prize)
The first peptide hormone humanity built from scratch was synthesized by a chemist who — by his own account — spent his wartime teenage summers milking cows, the one job oxytocin makes possible in the first place.
Oxytocin announced itself decades before anyone knew what it was. In 1906, the British pharmacologist Henry Dale found that extract of the pituitary's posterior lobe made a pregnant cat's uterus contract — an effect that took its name from the Greek for "swift birth." By 1910, Ott and Scott had shown the same extract forced milk let-down in lactating animals, and the obstetrician William Blair Bell had already reported, in 1909, injecting crude infundibular extract in obstetric patients whose uterus would not clamp down after delivery. For four decades that was the state of the art: delivery rooms ran on ground-up animal pituitary of variable strength, its active ingredient a chemical unknown.
The man who cracked it had learned the hormone's signature trick by hand. As a teenager during the First World War, Vincent du Vigneaud worked Illinois farms and — by his own later telling — got good enough at milking cows to briefly consider a life in agriculture. He chose sulfur chemistry instead, and the posterior-pituitary hormones sat squarely on that trail, because oxytocin's nine amino acids are pinched into a ring by a disulfide bridge. In 1952 his Cornell group isolated crystalline oxytocin; in 1953 it published the full sequence — as, independently and in the same year, did the Viennese chemist Hans Tuppy.
The synthesis — announced in 1953, published in full the next year by du Vigneaud with Charlotte Ressler, Panayotis Katsoyannis and colleagues — was the first time a peptide hormone had been built from plain chemicals. Would the lab-made molecule behave like the real one? Bioassays reported synthetic and natural oxytocin indistinguishable, the contemporary literature putting roughly one microgram intravenously at milk ejection within 20 to 30 seconds — a figure that reaches us through later reviews rather than a verified primary bioassay paper. The Nobel committee needed two years, awarding du Vigneaud the unshared 1955 Nobel Prize in Chemistry for "the first synthesis of a polypeptide hormone."
The priority claim holds: oxytocin genuinely was the first polypeptide hormone sequenced and synthesized, as the 1955 Nobel citation says — the "peptide" qualifier is load-bearing, since adrenaline and thyroxine were synthesized decades earlier. Three edges soften. The sequencing was not solo: Hans Tuppy published the same nine residues independently in 1953, and is routinely dropped from the retellings. The milking-cows framing is du Vigneaud's own retrospective account, not independently documented. And the "love hormone" second act rests on trust findings a 2015 critical review found had not replicated reliably.
Synthetic oxytocin is a WHO essential medicine for starting labor and preventing postpartum hemorrhage, and consequential enough that the Institute for Safe Medication Practices added it to its high-alert list in 2012. Its second identity has aged far less well. A 2015 critical review (Nave, Camerer and McCullough) concluded the intranasal-oxytocin trust finding had not replicated reliably, and that cumulative evidence does not robustly link oxytocin to human trust. The pharmacokinetics are awkward too: a 2013 study by Striepens and colleagues found intranasal oxytocin did raise cerebrospinal-fluid levels, but slowly — up to 75 minutes to reach significance — with no correlation between plasma and CSF concentrations, meaning the blood levels most behavioral studies measure say nothing about what reached the brain. Central effects are reported in their own right; how much sprayed peptide gets there, and by what route, stays open. None of that has stopped a research-chemical gray market selling vials and nasal sprays on the bonding story.
Synthetic oxytocin swept the animal-gland extracts out of the delivery room — but this molecule's strangest chapter came half a century later. In 2005, a study in Nature (Kosfeld and colleagues) reported that a few puffs of intranasal oxytocin made volunteers hand more money to strangers in a laboratory trust game. The christening was instant and permanent: the "love hormone." A decade of bonding studies and consumer nasal sprays followed, built on far shakier ground than the chemistry that won the Nobel. The 1953 synthesis has never needed correcting; almost everything the internet believes oxytocin does to the human heart came later, and much of it is now in open dispute.