Radiocarbon Can Interact With Biblical History

There were surprises when
radiocarbon dates augmented
studies of Iron Age Jerusalem.

 

Before getting into today’s story, some corrections must be made to popular notions of radiocarbon dating. Due to its short half-life of 5,730 years, ¹⁴C is only useful as a dating tool for a few thousand years of history—not millions of years—and the further back in time, the less accurate it becomes. At best, it can only suggest dates with decadal resolution. Even though radiocarbon labs using AMS (atomic mass spectroscopy) can identify individual ¹⁴C atoms in a sample, within 100,000 years all the radiocarbon in the world would have converted to other isotopes. That places an upper limit on dates obtained with radiocarbon.

The decay rate seems well established today, but has it ever changed? Science cannot know. Besides, radiocarbon dating depends on the production rate of ¹⁴C in the atmosphere, which depends on celestial factors like cosmic rays, supernovas, and the solar wind, which cannot be historically measured by using proxies such as tree rings and cave speleothems, which are one step removed from direct measurements. The 11-year solar cycle has been fairly reliable since it was first measured, but the intensity of flares affecting earth through human history cannot be known for each maximum. Flares from a very active sun might have pointed away from the earth in one cycle, but flares from a quieter solar maximum might have aimed directly at the earth.

How Radiocarbon Is Calibrated

It’s important to realize that radiocarbon dates are not the same as calendar dates. Unless they can be calibrated with historical information such as tree rings (dendrochronology) and written records of solar eclipses whose appearances can be calculated by celestial mechanics, they lack confidence. Another reason to distrust the very oldest radiocarbon dates is the reduction in artifacts with time that can be independently dated by written records. Radiocarbon can only be used on organic (carbon-containing) material, such as seeds, body parts and ash. To overcome the embedded assumptions in radiocarbon dating, scientists use a calibration curve to associate radiocarbon dates with calendar dates.

The latest calibration curve, adopted in 2020, is called IntCal20. It’s a “consensus” calibration, not an absolute calibration, because scientists make adjustments to it from time to time as understanding of atmospheric history changes. For instance, the curve had to be adjusted for post-1945 dates when scientists realized that above-ground atomic bomb tests had altered the production rate of ¹⁴C in the atmosphere. What other geophysical processes might have affected the amount of ¹⁴C remaining in a sample of interest? Even the latest calibration curve suffers from uncertainties. These include so-called “wiggles” and “plateaus” that result in ambiguous dates.

Giving due weight to these caveats, radiocarbon dating can be useful as an additional check on archaeological dates, particularly those in dispute. By interpolating radiocarbon dates with known anchor points in history, the method can prompt hypotheses about historical patterns at a site, offering potentially higher resolution dates than offered by other methods such as pottery styles. Such a study was just published in PNAS regarding Iron Age Jerusalem: the time of Kings David and Solomon. This will be of interest to Bible readers.

Regev et al., Radiocarbon chronology of Iron Age Jerusalem reveals calibration offsets and architectural developments (PNAS, 19 April 2024).

Surprised that radiocarbon dating had not previously been applied to ancient Jerusalem, a city of major historical interest, 18 mostly-Israeli authors participated in this study.

Absolute high-precision radiocarbon dating is pivotal in efforts to resolve complex historical and archaeological sequences. Jerusalem in the Iron Age (1200 to 586 BC) is a key site in its widespread archaeological importance but has not previously been a target for such an effort. The city has a history of 150 y of intensive archaeological excavations, stemming from the interest in ancient texts, particularly the biblical writings, which hold a thick and detailed historical record of king lists and significant political events. Surprisingly, though, radiocarbon dating was rarely applied for this period in Jerusalem, and the chronological frameworks were based solely on pottery typology, stratigraphy, and integration of textual sources.

To fill in this gap, they collected organic remains from multiple locations within the City of David (the southern portion of Jerusalem dating the 12th through 6th centuries), including seeds, ash from destruction layers, bone from a bat, and wood from houses. Microstratigraphy gave them unprecedented precision for interpolating sequential dates of artifacts between two anchor points, the well-known earthquake mentioned by Amos (c. 766-750 BC, identifiable in geological deposits), and the Babylonian destruction of Jerusalem in 586 BC.

The Bible as a Scientific Data Source

These authors treated Biblical references as data. Why? Because they know that the Hebrews, as “people of the book,” valued historical records as evidence of God’s working through their nation. Any reader of the chronicles in the Old Testament will surely be impressed with the amount of detail in their genealogies and historical accounts. Each king is mentioned by the year of succession after the prior king’s death or conquest. Sometimes narratives are tied to clues that can be investigated by other means, such as the mid-8th-century earthquake. For these reasons, the authors cited particular passages that informed their investigation, and mentioned “biblical” history, narratives and descriptions as if trustworthy at face value. Specific citations include:

• II Kings 15-16 – Narrative about the “Syro-Ephraimite War”
• II Kings 25:8-9 – Account of the Bablylonians burning the Temple
• Jeremiah 52:12-13 – The prophet’s eyewitness account of the Temple destruction
• Amos 1:1 – “in the days of Uzziah… and Jeroboam… two years before the earthquake”

The scientists also referred to Babylonian chronicles as a confirmation of the 586 BC date.

One contrast between Hebrew texts and those of surrounding nations is that Hebrew prophets wrote openly about the sins of their kings, whereas other nations’ narratives would often fudge or omit details to exaggerate their kings’ reputations. Scribes for Sennacherib, for instance, wrote that he had imprisoned King Hezekiah in Jerusalem “like a bird in a cage,” but failed to mention God’s destruction of his army.

Radiocarbon Agrees With Biblical Description

One of the goals of the scientists was to shed light on patterns of urban development in Jerusalem. At one point, they noted a trend:

Using these sequences, we identify regional offsets in atmospheric 14C concentrations c. 720 BC, and in the historically secure stratigraphic horizon of the Babylonian destruction in 586 BC. The latter is verified by 100 single-ring measurements between 624 to 572 BC. This application of intense 14C dating sheds light on the reconstruction of Jerusalem in the Iron Age. It provides evidence for settlement in the 12th to 10th centuries BC and that westward expansion had already begun by the 9th century BC, with extensive architectural projects undertaken throughout the city in this period. This was followed by significant damage and rejuvenation of the city subsequent to the mid-eight century BC earthquake, after which the city was heavily fortified and continued to flourish until the Babylonian destruction.

The radiocarbon results suggested moving one building phase earlier than thought:

Therefore, while the major building project of Jerusalem’s 8th-century BC fortifications was previously assigned to King Hezekiah in the late 8th century BC (e.g., ref. 59) based on our chronology, these activities can now be associated with the latter years of King Uzziah, whose reign spanned the mid-8th century BC, suggesting the city was fortified during the Syro-Ephraimite war (2nd Kings 15 to 16).

Findings about the early settlement of Jerusalem are of particular interest to Bible scholars:

Altogether, almost 20% of the samples (18 dates) fall within the timeframe of the early Iron Age (12th to 10th centuries BC, Fig. 4). This is highly significant, since only in three cases (RTD10780, 9598, 9585) do the dates derive from contexts with clearly associated early Iron Age pottery, while the remaining dates come from charred remains from building materials. The abundance of early Iron Age dates, measured from all the areas in our study, clearly indicates widespread occupation of yet undetermined character, often underestimated due to the limited architectural contexts attributed to this period.

In one room of a house on the southeastern slopes of the City of David, “Four dates assigned to the 16th, 12th, 10th, and 9th centuries BC were retrieved from a half-a-meter-thick accumulation of sediment and stones,” indicating longstanding occupation of the area.

Jerusalem Had a Long History

Radiocarbon also extended the length of settlement in the city farther back in time. At one site called Building 100, a “monumental building” constructed in the 9th century BC was found, and at other sites, the authors found evidence of earlier occupation:

Remarkably, while our radiocarbon determinations demonstrate a ~300-y use of Building 100 (Fig. 5), the pottery found in association with the building belongs almost entirely to the end of the 7th to the early 6th centuries BC, in the terminal Iron Age (for a similar assemblage, see ref. 35). Similarly, in Area U, long-term use is documented by the radiocarbon dates for several bedrock floors and the uppermost white-sediment floor of Room 17063 (see above). Also, in Area E, a white-sediment floor of Shiloh’s Stratum 12 (generally assigned to the 8th century BC) yielded four older dates. These observations suggest that these well-prepared, long-used floors were continually kept clean while in use so that most of the material accumulated on top of them originates from the final phase of occupation and the collapse of wall material from the structures. Thus, the radiocarbon determinations from various building materials and floors provide a more realistic approximation of the chronology of the analyzed structures and the history of occupation of buildings and entire settlements, than does the pottery and other remains of material culture.

This means that the evidence from pottery or burn layers could mislead archaeologists by hiding evidence of earlier activity.

One of the values from the radiocarbon evidence was filling in gaps from other data sources, such as pottery. The authors believe the radiocarbon dates establish significant earlier presence in Jerusalem before and during the important time of King David (1050 BC), who found Jerusalem to be a fortified city occupied by Jebusites that he and his army conquered.

We provide concrete evidence for a widespread human presence in the city during the 12th to 10th centuries BC, as short-lived material from all the areas studied was dated to these centuries. However, these contexts were often lacking diagnostic ceramics. This signifies that radiocarbon dating on a broad scale should be used to provide a more reliable site history, particularly in a densely rebuilt city, where foundations often reach the bedrock.

In summary, the radiocarbon study extended knowledge of early Jerusalem, giving additional clues that suggested early and extended occupation on the southeastern hill (City of David) as well as earlier construction on the western hill (Mount Zion). Even so, the scientists found offsets from the IntCal20 calibration curve that may require additional modification of the curve in the future.

While it’s encouraging to see radiocarbon dating supportive of the Bible’s account of Jerusalem, our authority is not radiocarbon but the Bible itself. Why not take it at face value? It claims to be the inspired word of God, recorded by men through whom the Spirit of God spoke. These Biblical writers came from all walks of life over a period of 1500 years, yet all agree on the nature of God, the history of the world, and responsibility of man to repent and believe His word. This study did not really add any new information. It just used one dating method (radiocarbon) to bring another dating method (pottery) more into line with what the Bible already said. Both methods, in turn, brought independent human research about Jerusalem back to the Bible.

The first mention of Jerusalem goes back to Genesis, where in Gen 14, Abram paid tithes of the spoils of war to Melchizedek, king of Salem and priest of the Most High God (see Psalm 110 and Hebrews 7). Whether Salem in this context refers to the same city of Jerusalem conquered by David almost a thousand years later is debated by scholars, but it well could be in the vicinity, perhaps near Mt Moriah (the later Temple Mount), which scholars believe was the site of the sacrifice of Isaac (Genesis 22). Joshua 10 mentions the King of Jerusalem among five kings conquered in the northern campaign, but according to Joshua 15 (after the division of the land), the city was still known as Jebus (Judges 19:10). It was not conquered by the tribe of Benjamin (Joshua 15:63) in Joshua’s day, but there was a partially successful campaign in the time of the judges (Judges 1:8-21). It was not until David’s commander Joab used the water system to scale the city and drove out the Jebusites that it became a fully Israelite city, and the rest is history—a long, eventful, sometimes glorious, sometimes tragic history. It was the city where our Lord was crucified and resurrected. He ascended from the Mount of Olives in sight of the city. Its name will be commemorated forever in the New Jerusalem, the city of the eternal state in heaven.

These are facts from the Word of God one can trust. Radiocarbon can be a useful tool in limited contexts, but is a bruised reed to lean on. See our earlier articles about it:

• Carbon Dating Is Becoming Useless (28 July 2022)
• Radiocarbon Calibration Is Stretchy (20 Aug 2020)
• Guesswork in Carbon Dating Exposed (25 May 2020)
• Radiocarbon Assumptions Questioned (21 Mar 2020)
• Radiocarbon Dating Is Not Globally Uniform (31 May 2018)
• “Extraordinary” Radiocarbon Anomaly Found in Tree Rings (19 Jan 2017)