Rethinking the Origins of the Lock
For over 200 years it has been generally believed that the first key-based locks originated in Egypt around 2000 BCE. However, recently there has been strong evidence emerging to place its invention elsewhere, and suggest a more accurate, if somewhat broad window in which the first lock entered the world.
Relying on the efforts of some amazing archaeologists and linguists, I propose that that the first key-based locks originated in Mesopotamia between 2500 & 1800 BCE.
There were a few significant pieces of evidence to point to a middle-eastern origin of the lock, but what specifically led to the re-introduction of the pin-lock to modern, European society were the journals of Vivant Denon.
Denon was a talented etcher, pornographer, and diplomat, and perhaps the most eloquent European to bear witness to the antiquities of Upper Egypt. He served in Napoleon's "corps des savants", a cohort of 170 scholars from disparate fields. They were attached to the French military force that carried out the failed conquest of Egypt at the tail end of the 18th century. While Denon's skill as an artist was occasionally used in the production of military illustrations, his primary mission was to explore and record the ancient ruins of the area.
...Denon was to be found busy sketching battlefields and soldiery for the glorification of the regime, but he was also tireless in seeking out and cataloging artifacts for transportation to Paris, his principal commission, with total indifference to the humiliation of the subject nations that were being robbed...he was in fact a looter on a scale that makes Hermann Goering look like something of an amateur. Under him, Napoleon’s Paris, the new Rome, swiftly became the greatest art metropolis the world had ever seen.
—The Age of Napoleon by Alistair Horne
Denon certainly arrived with romantic sensibilities about his adventure, writing to Isabella Teotochi-Albrizzi that "...you have never been loved from Egypt. possibly it will be on the pyramids that I get to inscribe your name." However, the reality wasn't nearly so exciting. For the first several months Denon was catastrophically sharing time with the entire Corps des Savants, and a massive military force. Rather than antiquities, he was primarily surveying modern, if modest, villages. While he dutifully sketched their garments, towns, and the formations of the French military, he was aching to find a way out into the more desolate reaches of Egypt.
His opportunity came in November of 1798. A few months prior General Desaix had been tasked with hunting down a guerrilla cavalry force lead by the Mumlak leader, Murad Bey. Murad and Ibrahim Bey had united to form a duumvirate that held de facto control over Egypt in defiance of the Ottoman empire. When Napoleon's army arrived, he quickly found himself at war with both Ottoman Turks and Mumlak warriors. At the battle of the pyramids, the French managed to scatter the Mumlak soldiers, with Ibrahim breaking toward the Sinai, and Murad retreating deep into upper Egypt. Desaix soon discovered that Murad Bey was well protected in Upper Egypt, so he sent for General Belliard. While Upper Egypt had been explored by a handful of Europeans throughout the 1700s, there remained many great mysteries, and few illustrations from the prior travelogues. Denon seized the opportunity to make his mark, and successfully petitioned to separate from the rest of the scholarly brigade and travel with Belliard and Desaix, with whom he established great friendships, though their motivations were always at odds. Desaix was on a military campaign, Denon, a scholarly exploration, a friction made clear by an incident near El-Araba.
I knew that I was near Abidus, where Osymandyas had built a temple, and where Memnon had resided. I was constantly urging Desaix to send thither a reconnoitering party as far as El-Araba, where I daily heard there were several ruins; and as often Desaix said to me "I will conduct you thither myself. Murad-Bey is two days journey from us; he will come up to us the day after tomorrow, and we shall then give him battle, and when we shall have beat him, we can then bestow as much time as you will on antiquities, and I will help you myself to measure them." My good friend was certainly in the right, and even if it were not so, I must have contented myself.
At last on the 22nd, we quitted Girgeh at the approach of night, and we passed directly opposite to the antiquities. Desaix dared not look me in the face: "If I am killed tomorrow," said I to him, "my ghost will be always haunting you, repeating in your ears El-Araba."
—Travels in Upper and Lower Egypt by Vivant Denon, translated by Arthur Aikin 
This was a purely opportunistic exploration, as Denon was well aware, noting in Travels in Upper and Lower Egypt, his published record of the trip, "I was therefor sometimes obliged to pass rapidly over the most interesting monuments; and at other times to stop where there was nothing to observe." Despite the transient nature of his explorations, Denon became the first modern European to document the ruins at Thebes, Esna, Edfu and Philae among others. The written account of his travels and myriad illustrations created incredible excitement and stoked the newly popular Egyptian art and fashion fashion revival in Europe. Of particular note to lock historians, though, was Desaix's arrival at Karnak in July of 1799.
We arrived at sunrise at Karnak, where I did the honors of introducing newcomers to the site. At the same time, I checked the the accuracy of my first operations. Among the new discoveries that I made through the rubble of the temple, I will quote a figure that I perceived on the outside walls of the small buildings that are next to the sanctuary. It was that of a character making an offering of two obelisks. I also noticed the representation of a temple gate, with two folding doors, shut by exactly the same kind of wooden bolts that are at present made use of. The excessive heat did not allow me to stop for a moment where the two bas-reliefs were located, and therefore draw them, but we can infer from these sculptures that obelisks, and such kind of monuments, were the votive offerings of princes and other great personages; and that even less monumental objects, such as doors, were also pious offerings...
—Travels in Upper and Lower Egypt by Vivant Denon, translated by Arthur Aikin
Unfortunately, Denon's translator, Mr. Aikin, chose to translate the French word "serrure" as "bolt" instead of the more accurate "lock", and for some reason neglected to translate the conclusion of Denon's thought, which turns out to be quite beautiful: 
...and finally that inventions of general utility are transmitted by a tradition that runs through all revolutions of nations. The image I give of an absolutely modern lock can stand in as a drawing of the ancient one, as I did not notice any difference.
The locks he was comparing the relief to could be found in use all over the middle east at that time. The design was ancient, as evidenced by both the relief and some artifacts recovered from other sites, yet had somehow persisted, nearly unchanged, for thousands of years. Working off of the original French publication and the plates Denon provided, engineers in England presented papers and commentary at the Royal Institution where it caused a great deal of excitement and speculation.
The simplicity and other advantages of this lock or bolt, are too obvious to require much remark; for which reason I shall confine my present observations to its degree of security or inviolability... We may admit that the ancient lock, with many pins falling independently of each other, cannot be picked or opened without its key... Now, if there be a number of these pins so placed and adjusted as to fall into their respective sockets at the position of the bolt when shut; if their lower tails be of different lengths, and a key be made to correspond with them, and lift them all to the proper height at once; the combination will be such as cannot be made out by any impression or tentative process upon the lock itself.
W. Nicholson, A Journal of Natural Philosophy, Chemistry, and the Arts, 1804 
Only months after the publication of Denon's journals we can see the seeds of what would become the most popular lock in the world grow out of the ancient design. Soon, Stansbury would file the first patent for a pin lock, followed a few decades later by Linus Yale Sr.'s pin tumbler padlock, and finally, Linus Yale Jr.'s pin tumbler door lock. Though I may object to the timeline and even the geography of the "Egyptian Lock", I cannot help but marvel at its extraordinary staying power. From a carving at Karnak to your front door, Denon's beautiful sentiment "that inventions of general utility are transmitted by a tradition that runs through all revolutions of nations" certainly rings true.
Disrupting the Timeline
Prior to Denon's travelogue, metal keys and even some wooden locks dating as far back as the 6th and 7th centuries BCE had been discovered which supported the existence of the pin tumbler lock in antiquity. Unfortunately, Denon, in a description of an etched plate, included an offhand comment suggesting that the Egyptian lock had been in use for much longer than the artifactual record could prove.
The Egyptian lock: it closes the door of the city, that of the house, as well as the smallest piece of furniture. I have placed it among the antiquities, because it is the same as that which was used there for four thousand years that I have found sculpted among the reliefs adorned on the great temple of Karnak. A simple design, easily executed, as sure as all other locks, it should be used to close all our rural fences.
—Vivant Denon, Voyages dans la Basse et la Haute Egypte, 1798-1799 
Despite only having physical artifacts from the first millennia BCE, this was the phrase that would be forever repeated by excited European and American scholars for the next 200 years. However, that idea of 4000 year old Egypt pervades both Denon's journals and Napoleon's speeches. It clearly becomes a routine, but incredibly vague, manner for expressing ancient gravitas on the entire campaign, both military and academic. On the contrary, Egyptian culture spanned more than 3000 years. It's art, architecture, and basic structures of religion and government, while malleable, remained recognizably "Egyptian" through that time. To disrupt Denon's timeline, we first need to narrow in on exactly where he was, and what he was looking at.
Karnak alone was developed over nearly 1000 years, with architectural contributions from 30 heads of state, and the site itself is massive. While Denon mentions in his journal that the oppressive heat on the day they arrived in Karnak was such that he could not stop to make an illustration of the relief, so frustratingly we don't have what we need to do an exact comparison. He does give us some clues about where he was looking, though. He mentions an offering of two obelisks, a town gate, and lock upon the gate. He also goes on to describe the possible implications of these objects appearing together, so we know that they weren't three reliefs spread out around the complex. I reached out to Dr. Elaine Sullivan, of the Digital Karnak project at UCLA , who was kind enough to point me to this well preserved relief of Thutmose III making an offering of two large obelisks.
Dr. Sullivan was unaware of the town gate or lock, but as ruins, unfortunately, continue to be ruined, what Denon saw may now be dust. The offering, however, was quite clear, and puts Denon inside of The Palace of Ma'at. Built by Hatshepsut who reigned for more than 20 years in the middle of the 15th century BCE, even if the relief did depict a pin lock, at the time of Denon's discovery it would have only suggested an age of 3200 years. We can forgive Denon his enthusiastic inexactitudes as he was speaking in fairly general terms, and trying to instill a sense of wonder at the nearly unchanged technology of modern middle eastern locks. It must have been thrilling to witness, all around him, such a direct connection to the ancient world. However, the incessant repetition by lock historians has obscured what could be the true origins of the first mechanical lock.
Also at Karnak, on the North wall of Hypostyle Hall, there is a small relief that depicts an older concept in locking doors. The mostly destroyed images show Seti I opening the shrine of Amun-Ra as part of a daily ritual offering. 
In the carving, now called Episode C, you can clearly see him removing a peg that runs through the door. Though Seti I built hypostyle hall nearly 200 years after the death of Hatshepsut, this is a clear depiction of an even older method of securing doors than locks, the clay seal. Door seals have their own history, even more ancient than mechanical locks. The discovery of door seals at Tell-e Bakun provide us artifactual evidence for their existence as early as 4400 BCE. Abbas Alizadeh, writing in Tell-e Bakun A: The Origins of State Organizations in Prehistoric Highland Fars suggests that "Door sealings may be taken as the earliest tangible evidence of the evolutionary transition from a tribal to a civilized society."
To secure a door, you would have a cord attached to a plank inside the door. This cord would run out the door and into the clay plaque. The plaque had a square or circular hole in the middle that a peg would be placed through, securing it to the wall. To open the door, one only needed to remove the peg, but once closed more clay would be added to the plaque, covering and securing the peg. This could be easily broken off, of course, but unless you could reproduce the intricate seal it would be obvious that someone had trespassed. This peg-through-plaque system seems like fertile ground for the innovation that would become the pin tumbler lock, and linguistic analysis may bear that out.
Clues in the Cuneiform
In the late 1980s there was an uptick in academic interest in Mesopotamian door seals and locking systems. With minimal artifactual evidence, scholars looked to clues in Sumerian and Akkadian writing to clarify their idea of ancient security devices. Following on papers published by 2 of his peers, Dr. Daniel Potts, professor of Middle Eastern Archaeology at the University of Sydney, entered the fray in 1990 with his article, “Lock and Key in Ancient Mesopotamia”  which found a home in an Italian academic journal bluntly titled “Mesopotamia.” In the article he quickly identifies the root problem inherent in this kind of speculative research: interpretation.
Both E. Leichty and J.A. Scurlock wrestle valiantly with the Sumerian and Akkadian phraseology of locking, each trying to assign the various termini technici mentioned in cuneiform sources to one or another part of the locking system they believe to have been common in Mesopotamia. The results are completely different, as they must be, given the fact that each believes a different sort of locking mechanism was prevalent in the region.
—Daniel Potts, Lock and Key in Ancient Mesopotamia
Both Leichty and Scurlock had attempted to bring the limited archaeological evidence available to bear in selecting the type of locking system they then bent the language to describe. Leichty used impressions left in the back of well-preserved clay seals to extrapolate the likely mechanisms they had been covering. Scurlock used the reconstruction of a lock found at a site called Tchoga Zanbil as his base. Each used their chosen example to define a collection of words that regularly occurred together in ancient writing. For his part, Potts believed that neither had hit upon the right concept for defining all of the parts of the locks in context. He proposed something else.
The difficulty of identifying these parts correctly lies, to begin with, in the choice of the correct lock system as a model, and thereafter in finding identifications which, in association with all of the other relevant terms, make mechanical sense. In contrast to Leichty and Scurlock, I propose to use the Egyptian lock as a model for the identification of the most important terms.
— Daniel Potts, Lock and Key in Ancient Mesopotamia
By “Egyptian lock” he was, of course, referring to the early pin lock. Using the pin lock as a model he was able to create coherent translations of several specific cuneiform passages. Of particular note was an ancient complaint found in a passage labeled “CT 40 12:7-15.” Using the pin lock for context, we can see that the complaint charges that the pins (or sikkatu) in the lock (namzaqu) of the Istar temple weren't properly aligned with the pin chambers (uppu) in the bolt (aškuttu), so that when the key lifted the pins up, they couldn't fall back down again. This, as any modern locksmith would know, prevented the proper operation of the lock.
Potts’ proposed definitions also provide an exciting clue to the possible evolution of the world’s first mechanical lock. The sikkatu, translated as the pins in the pin lock, was precisely the same word used for the peg in the ancient Assyrian door seals. If Potts’ theories could be confirmed this bit of information might provide the linguistic evidence of a direct mechanical evolution from door seals to keyed locks.
8 years later, Andreas Fuchs, participating in the Neo-Assyrian Text Corpus Project, published “Die Annalen des Jahres 711 v. Chr. nach Prismenfragmenten aus Ninive und Assur.”  In one section, Fuchs set out to analyze the same constellation of lock terms Potts, Leichty and Scurlock had examined. The basis for his analysis was a list of the spoils of a campaign of King Sargon II. Sargon had removed the lock from the Haldi temple at Musasir as its various parts were beautifully made of gold. The perceived value meant that the loot was well described in the accounting. This gave Fuchs the information he needed to not only identify the object as a pin lock, but even reconstruct it, drawing remarkably similar conclusions to Potts work.
Further confirmation of the existence of pin locks in Assyria was found in a 7th century BCE letter from a temple to their king, stating that an apprentice to “Adad” somehow managed to lose the key to the temple. While it does not explicitly mention the type of key or lock, the pin lock was the only security technology known at that time that actually used a key.
Unfortunately, this linguistic analysis, as advanced as it was becoming, was lacking an important component, an actual artifact to compare against. Then, in 2001, David and Joan Oates published “Nimrud: an Assyrian Imperial City Revealed” , which collected decades of discoveries, including hard artifactual evidence of one of the oldest parts of a pin lock ever discovered. The artifact was a thin brass plate with 3 slots and a protruding knob. This find offers the oldest physical confirmation of the linguistic approach.
When I was trying to tease out the linguistic connection between the door seal and the pin lock, Dr. Potts was kind enough to direct me to the work of Dr. Karen Radner of the University College of London. In her 2010 paper “Gatekeepers and Lock Masters: The Control of Access in Assyrian Palaces” , Radner identifies the plate the Oates' had found as the lock’s “holding bar.” Radner goes on to not only re-confirm the existence of the pin lock, but place the technology in context with the daily life of the palaces and temples of Assyria. She sets out to identify the Lock Masters, those officers of the temple who controlled the locks and keys.
In defining the official title “rab sikkāte” as Lock Master, Radner also provides a compelling argument for the pin lock having wholly replaced the door seal, and reinforced my suspicion that the linguistic connection between the two technologies was legitimate.
I therefore propose the translation ‘lock master’, assuming that the crucial component sikkatu denotes--pars pro toto--the lock in its entirety. This is all the more likely as the sikkatu is the central element of the more primitive locking mechanism...Suzanne Herbordt, when studying the 565 Neo-Assyrian clay sealings from Nineveh, was unable to identify a single example for such a door sealing...This would indicate that the system was no longer in use at that time, and I would suggest that this was so because it had been replaced with the sikkatu lock.
Dr. Karen Radner, Gatekeepers and Lock Masters: The Control of Access in Assyrian Palaces
So, with mounting evidence for the existence of the pin lock in Assyria, and a reasonable case for the evolution from the ancient Mesopotamian door seals, the only question that remains is when did that evolution take place? Radner mentions in her article that the terms she was attempting to define were attested in public documents at least as far back as the Old Babylonian period, around the 18th century BCE. Artifacts of door seals have been found deep into the third millennium BCE.
Lacking further linguistic or artifactual evidence, we have to be satisfied to narrow the evolution of the pin lock to Mesopotamia, sometime between 2500 and 1800 BCE.
Though this period does, rather satisfyingly, predate Denon’s discoveries in Egypt, it also finally gives credence to his offhand suggestion that the locks used on doors to this day may have had their origins 4000 years ago. Redefining the origin of the lock does more than settle (or reignite) a debate in a niche community. The Mesopotamian theory provides a window into the nature of the role of security in society. By following the lock back to its more primitive technological ancestors, we can begin to build a theory for not just how, but why this ubiquitous object came into existence in every society the world has known.
I owe a great deal to Dr. Daniel Potts, whose paper initially inspired my curiosity, and his enthusiastic response to an unsolicited email set me off on an exciting path of research.
My thanks Dr. Elaine Sullivan for her aid in identifying the area Denon observed, but could not illustrate in his journals. And many thanks to everyone at the Digital Karnak project whose work is of a scale to match that incredible site.
Additionally, I must thank Dr. Karen Radner for her considered reply to my questions regarding the time gap between the last door seals and first evidence of the "sikkatu" lock. And, more personally, for sending along the cuneiform for "Lockmaster":
Additional thanks to Deb Chachra, Adam Sheesley, and Julie Steele who all read, or talked through, various iterations of this work.
Travels in Upper and Lower Egypt: during the campaigns of General Bonaparte in that country : and published under his immediate patronage, Volume 2
Vivant Denon, Arthur Aikin
Printed by Heard and Forman for Samuel Campbell, 1803
Voyages dans la Basse et la Haute Egypte, pendant les campagnes de Bonaparte, en 1798 et 1799, Volume 1
Livre numérique Google
S. Bagster, 1807
Photograph of interior wall of Hypostyle Hall
Digital Karnak project
Certain Reliefs at Karnak and Medinet Habu and the Ritual of Amenophis I
Harold H. Nelson
Journal of Near Eastern Studies, Vol. 8, No. 3 (Jul., 1949), pp. 201-232
The University of Chicago Press
Tell-e Bakun A: The Origins of State Organizations in Prehistoric Highland Fars, Southern Iran Excavations at Tell-e Bakun
Abbas Alizadeh, with contributions by Masoumeh Kimiaie, Marjan Mashkour, and Naomi F. Miller
Oriental Institute Publications (2006)
The Oriental Institute at the University of Chicago
Photograph of "Banquet Plaque" door seal
The Oriental Institute at the University of Chicago.
Locky[sic] and Key in Ancient Mesopotamia
Mesopotamia (Torino) 25 (1990), pp. 185-192
Die Annalen des Jahres 711 v. Chr. nach Prismenfragmenten aus Ninive und Assur
State Archives of Assyria Studies, Volume VIII
by Andreas Fuchs
Nimrud: An Assyrian Imperial City Revealed
Joan Oates, David Oates
British School of Archaeology in Iraq, 2001
Gatekeepers and lock masters: the control of access in the Neo-Assyrian palaces
H. D. Baker, E. Robson & G. Zolyomi (ed.),
Your Praise is Sweet. A Memorial Volume for Jeremy Black (London 2010) 269-280.