How long have peptides been around?
More than a century. In 1901 Emil Fischer made glycylglycine, two amino acids joined in a lab, a landmark of early peptide chemistry. Walk the timeline from that moment to today's GLP-1 revolution.
125 Years on One Timeline
Peptide science begins in 1901 with a single lab bond and runs straight through to today's $30B GLP-1 era. Click any milestone below to see what happened, who did it, and why it mattered.
Era 1: The Pioneers (1901-1953)
Three people. Three breakthroughs. Together they turned peptides from a curiosity into a science, proving the building blocks of life could be built, injected, and read.
1901
Emil Fischer
Stitched two amino acids into glycylglycine, his first peptide synthesis. Histories of peptide chemistry trace the field from Theodor Curtius before him, through Fischer, to Bruce Merrifield.
1922
Banting & Best
A 14-year-old dying of type 1 diabetes was injected with pancreatic extract in Toronto on January 11. It did nothing. A purer extract on January 23 worked, and daily injections gave him 13 more years.
1953
Frederick Sanger
Spent 10 years piecing insulin together like a jigsaw with no picture on the box. Showed proteins aren't random blobs, they're precise machines.
Era 2: The Synthesis Revolution (1963-1982)
Knowing a peptide's recipe was one thing. Building it was another. Two breakthroughs (one chemical, one biological) turned peptides from rare lab samples into industrial drugs.
Before 1963
Peptide synthesis was brutal
Even a short peptide meant painstaking solution chemistry: add one amino acid, purify, add the next, purify again. Each intermediate had to be isolated by hand.
After 1963 (Merrifield)
Solid-phase synthesis (SPPS)
Bruce Merrifield built the chain on an insoluble solid support. Each cycle adds one amino acid and washes the leftover reagents away, while the growing chain stays put.
1977
Bacteria make somatostatin
Scientists built the gene for somatostatin, a 14 amino acid hormone, by chemistry and put it into E. coli, which then made the hormone's sequence. The paper calls it the first functional product of a chemically made gene.
1982
Humulin approved by FDA
Human insulin grown in bacterial vats instead of harvested from pig pancreases. We no longer needed to borrow molecules from animals -- we could tell bacteria what to build.
Era 3: The Discovery Era (1992-2005)
Once we could build peptides, the next question was where to find new ones. The most important answer came from somewhere nobody was looking.
A related lizard's venom had just yielded a hormone-like peptide, and that prompted John Eng to search Gila monster venom. In 1992 he isolated exendin-4. It turned out to act on the receptor for human GLP-1, the hormone that boosts insulin release. The difference that mattered: your body's own GLP-1 lasts under two minutes in the blood, while exenatide, the drug copied from exendin-4, has a half-life of about 2.5 hours.
The source
Why venom was worth a look
Exendin-4 is not the only venom peptide to become a medicine. Ziconotide, a non-opioid pain drug, is a synthetic copy of a cone snail venom peptide. What exendin-4 offered was staying power that human GLP-1 lacks.
The problem it solved
The two-minute half-life
Your own GLP-1 is cut up by an enzyme called DPP-4 and lasts under two minutes in the blood, far too short to work as a medicine. Exenatide, the copy of exendin-4, has a half-life measured in hours instead of minutes.
The molecule
Exendin-4 becomes exenatide
Exendin-4 acts on the same receptor as human GLP-1 yet holds up far longer. Chemists made a synthetic copy of the lizard peptide and named it exenatide, the active ingredient in the first diabetes drug built on GLP-1.
1992
Isolated from the venom
Eng pulled exendin-4, a 39 amino acid peptide, out of Gila monster venom. Its synthetic copy, exenatide, later proved to be a long-lasting agonist at the GLP-1 receptor.
2005
13 years from venom to pharmacy
In 2005, the FDA approved exenatide (brand name Byetta), the first diabetes drug built on GLP-1, copied from a desert reptile's venom. Nobody knew it yet, but this was the seed of a $30 billion revolution.
Era 4: The GLP-1 Revolution (2017-2024)
Novo Nordisk's semaglutide carries a fatty-acid chain that binds albumin in your blood, which stretches its half-life enough for one injection a week. That is when the drug class went mainstream.
2017
Ozempic
Mechanism: GLP-1 agonist
Dosing: once weekly, thanks to albumin binding
Approved: for type 2 diabetes.
2021
Wegovy
Mechanism: GLP-1 agonist (higher dose)
Weight loss: 14.9% (2.4% on placebo) in its main trial
Approved: for chronic weight management.
2022
Mounjaro
Mechanism: GLP-1 + GIP dual agonist
Weight loss: 20.9% at the top dose (3.1% on placebo) over 72 weeks in SURMOUNT-1, its obesity trial
Impact: brought a two-receptor agonist into the clinic.
The Four Eras at a Glance
Each era solved the problem the previous one created -- discovery → manufacture → biology → medicine at scale.
Era 1 · 1901-1953
Pioneers
Made a peptide in a lab, proved one can save a life, mapped insulin's sequence.
Era 2 · 1963-1982
Synthesis Revolution
SPPS made building peptides routine; Humulin made bacteria the new factory.
Era 3 · 1992-2005
Discovery Era
Gila monster venom delivered exenatide, the first diabetes drug built on GLP-1.
Era 4 · 2017-2024
GLP-1 Revolution
Once-weekly peptides reshaped obesity medicine and built a $30B drug class.
What's Next? Three Races, Right Now
Three races are happening simultaneously, and each could change what peptide therapy looks like within the next few years.
Race 1
The end of needles
Oral semaglutide showed a peptide pill can work, though only a small fraction of each dose is absorbed. Orforglipron is a small-molecule GLP-1 agonist (not a peptide) built to be swallowed like aspirin. The FDA approved it for weight loss in April 2026 as Foundayo, so for some patients injections are now optional.
Race 2
Stacking receptors
Tirzepatide hits two receptors. Retatrutide hits three (GLP-1, GIP, and glucagon) and a phase 2 trial showed 24.2% body weight loss at 48 weeks (2.1% on placebo). Its first phase 3 readout, TRIUMPH-4, reported 28.7% at 68 weeks (2.1% on placebo) in a company release. It is not yet approved.
Race 3
AI-designed peptides
Researchers are using machine learning to design new peptide sequences and tune their stability and binding to a target. Whether any of these designs becomes an approved drug is still an open question.
Common Questions About Peptide History
Short, sourced answers to the questions people ask most about when peptides were discovered, who discovered them, and how old the science really is.
When were peptides discovered?
Peptide science is well over a century old. In 1901 Emil Fischer joined two amino acids into glycylglycine in a lab, and histories of the field start even earlier, with Theodor Curtius.
Who discovered peptides?
No single person. Theodor Curtius and Emil Fischer were early peptide chemists, and Fischer made glycylglycine in 1901. Frederick Sanger later sequenced insulin in 1953, and Bruce Merrifield invented solid-phase synthesis in 1963, work that won the 1984 Nobel Prize in Chemistry.
Are peptides natural or synthetic?
Both. Peptides occur naturally in every living organism (insulin, oxytocin, and glucagon are natural peptides) and they can also be made synthetically. A lab-made copy can match a natural peptide exactly, as human insulin from bacteria does, but many peptide drugs are deliberately modified versions built to last longer.
What was the first peptide drug?
Insulin. In 1922 it saved 14-year-old Leonard Thompson, who was dying of type 1 diabetes in Toronto. In 1982, Humulin became the first recombinant-DNA peptide drug, made by reprogramming bacteria to produce human insulin.
- Goodman M et al. "The bold legacy of Emil Fischer." J Pept Sci. 2003;9(9):594-603. PMID 14552421
- Lewis GF, Brubaker PL. "The discovery of insulin revisited: lessons for the modern era." J Clin Invest. 2021;131(1):e142239. PMID 33393501
- Stretton AOW. "The first sequence: Fred Sanger and insulin." Genetics. 2002;162(2):527-532. PMID 12399368
- Ryle AP, Sanger F, Smith LF, Kitai R. "The disulphide bonds of insulin." Biochem J. 1955;60(4):541-556. PMID 13249947
- Mitchell AR. "Bruce Merrifield and solid-phase peptide synthesis: a historical assessment." Biopolymers. 2008;90(3):175-84. PMID 18213693
- Parkes DG et al. "Discovery and development of exenatide." Expert Opin Drug Discov. 2013;8(2):219-44. PMID 23231438
- Jastreboff AM et al. "Tirzepatide Once Weekly for the Treatment of Obesity." N Engl J Med. 2022;387(3):205-216. PMID 35658024
- Jastreboff AM et al. "Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial." N Engl J Med. 2023;389(6):514-526. PMID 37366315
- Lambert C, Delgado E. "100 Years since the Discovery of Insulin, from Its Discovery to the Insulins of the Future." Biomedicines. 2024;12(3):533. PMID 38540146
- Kimmerlin T, Seebach D. "'100 years of peptide synthesis': ligation methods for peptide and protein synthesis." J Pept Res. 2005. PMID 15705167
- Novo Nordisk. "WEGOVY (semaglutide) injection, US prescribing information." PDF as served on the fetch date. novo-pi.com wegovy.pdf
- Eng J, Kleinman WA, Singh L, et al. "Isolation and characterization of exendin-4, an exendin-3 analogue, from Heloderma suspectum venom." J Biol Chem. 1992;267(11):7402-7405. PMID 1313797
- FDA. Drugs@FDA application record for BYETTA (exenatide), NDA 021773, via the openFDA drugsfda API. NDA 021773
- Li Q, Chao W, Qiu L, et al. "Therapeutic peptides: chemical strategies fortify peptides for enhanced disease treatment efficacy." Amino Acids. 2025. PMID 40338379
- Zheng B, Wang X, Guo M, Tzeng CM. "Therapeutic Peptides: Recent Advances in Discovery, Synthesis, and Clinical Translation." Int J Mol Sci. 2025;26(11). PMID 40507941
- AstraZeneca Pharmaceuticals LP. "BYETTA (exenatide) injection, US prescribing information." Revised 09/2025. PDF as served on the fetch date. accessdata.fda.gov 021773Orig1s051correctedlbl.pdf
- Eli Lilly and Company. "FDA approves Lilly's Foundayo (orforglipron), the only GLP-1 pill for weight loss that can be taken any time of day without food or water restrictions." News release, April 1, 2026. investor.lilly.com Lilly news release, April 1, 2026
- Eli Lilly and Company. "Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial." News release, December 11, 2025. investor.lilly.com Lilly news release, December 11, 2025
- Lin H, Vogel H, Zhang H, et al. "A Comparative Review of Artificial Intelligence Applications in Small Molecule Versus Peptide Drug Discovery." Int J Mol Sci. 2026. PMID 41977325
- Nobel Prize Outreach. "The Nobel Prize in Chemistry 1984." Summary page as served on the fetch date. nobelprize.org Nobel Prize in Chemistry 1984
- Itakura K, Hirose T, Crea R, et al. "Expression in Escherichia coli of a chemically synthesized gene for the hormone somatostatin." Science. 1977;198(4321):1056-1063. PMID 412251
- Novo Nordisk. "OZEMPIC (semaglutide) injection, US prescribing information." Revised 05/2026. PDF as served on the fetch date. novo-pi.com ozempic.pdf
- Solis-Herrera C, Kane MP, Triplitt C. "Current Understanding of Sodium N-(8-[2-Hydroxylbenzoyl] Amino) Caprylate (SNAC) as an Absorption Enhancer: The Oral Semaglutide Experience." Clin Diabetes. 2024;42(1):74-86. PMID 38230324
- Nakmode DD, Singh B, Abdella S, et al. "Long-acting parenteral formulations of hydrophilic drugs, proteins, and peptide therapeutics: mechanisms, challenges, and therapeutic benefits with a focus on technologies." Drug Deliv Transl Res. 2025. PMID 39661312
- Deacon CF, Johnsen AH, Holst JJ. "Degradation of glucagon-like peptide-1 by human plasma in vitro yields an N-terminally truncated peptide that is a major endogenous metabolite in vivo." J Clin Endocrinol Metab. 1995;80(3):952-957. PMID 7883856
- Ashraf AR, Mackey TK, Vida RG, et al. "Multifactor Quality and Safety Analysis of Semaglutide Products Sold by Online Sellers Without a Prescription: Market Surveillance, Content Analysis, and Product Purchase Evaluation Study." J Med Internet Res. 2024;26:e65440. PMID 39509151
Knowledge Check
Test what you learned in this module.
Practice Exercises
Reinforce your understanding with interactive exercises.