First we need to ask: What is radiocarbon dating?
There’s been a lot of debate around the issue of Bible chronology, which more specifically relates to the era of the reigns of David and Solomon. Did they live in the archaeological period known as Iron Age I, which is archaeologically poorly documented, or in Iron Age IIa, for which more evidence is available. Proponents of low Bible chronology, called minimalists, claim the transition occurred around 920 to 900 B.C. Proponents of a high Bible chronology put the date around 1000 to 980 B.C. Some scholars have asked if radiocarbon dating accuracy will help settle the question.
What is radiocarbon dating? Radioactive carbon-14 is used to analyze an organic material, such as wood, seeds, or bones, to determine a date of the material’s growth. Is radiocarbon dating accuracy indeed more reliable to determine Bible chronology than traditional dating methods that rely on archaeological evidence that looks at strata context? In the following article, “Carbon 14—The Solution to Dating David and Solomon?” Lily Singer-Avitz attempts to answer these questions.
In answering “What is radiocarbon dating?” she enumerates some of its deficiencies. Radiocarbon dating accuracy has its limits. The material’s period of growth might be many decades from the era in which it was used or reused, say, in building construction. Calibration procedures are complex and periodically revised as new information comes to light, skewing the radiocarbon dating accuracy. And statistical models also vary from researcher to researcher. Ultimately, radiocarbon dating accuracy for calculating Iron Age dates, and consequentially Bible chronology, has varied from researcher to researcher. When it comes to Bible chronology, the difference between a “high” and “low” chronology is a matter of mere decades, not centuries.
Singer-Avitz claims the material evidence of archaeological stratigraphy, including pottery finds, should not take second place. What is radiocarbon dating? A useful tool but only one and not the only when it comes to determining Bible chronology.
The date of the transition from the archaeological period known as Iron Age I to Iron Age IIa is a particularly hotly disputed topic, especially because the date of the transition is crucial for elucidating the history and material culture of the reigns of David and Solomon.
According to the so-called high chronology, the transition occurred around 1000 or 980 B.C.E. It is generally recognized that David conquered Jerusalem in about 1000 B.C.E. According to the low chronology, the transition to Iron Age IIa occurred around 920–900 B.C.E. Other opinions place the transition somewhere between the two—in about 950 B.C.
The date is important because the date you choose will determine whether David and Solomon reigned in the archaeologically poor and archaeologically poorly documented Iron I or in the comparatively rich and richly documented Iron IIa.
However, the differences in data between the various schools are not dramatically far apart. They range between 30 and 80 years.
In an attempt to solve this chronological problem and to achieve a more accurate date for the transition period, many scholars have resorted to carbon-14 (or radiocarbon) analysis, which can be performed on any organic substance, like wood or grain. Radio-carbon dating is regarded by many scholars as accurate, precise and scientific, in contrast to the old cultural-historical methods of dating archaeological strata, which the devotees of radiocarbon regard as inaccurate and intuitive. The hope of many scholars who feel that this science-based radiocarbon research will bring the debate to its longed-for solution is, in my view, difficult to adopt.
The question I would like to raise is whether radiocarbon dating is really more precise, objective and reliable than the traditional way of dating when applied to the problem of the date of the transition from Iron I to Iron IIa. This question is sharpened in light of the fact that the uncertainty in the usual radiocarbon readings (plus or minus 25 years or so) may be as large as the difference in dates in the debate.
Interested in the latest archaeological technology? Researchers at the UCSD’s Calit2 laboratory released the free BAS eBook Cyber-Archaeology in the Holy Land — The Future of the Past, featuring the latest research on GPS, Light Detection and Ranging Laser Scanning, unmanned aerial drones, 3D artifact scans, CAVE visualization environments and much more.
The radiocarbon dating has several serious difficulties:
(1) Sample selection. Measuring the remaining carbon-14 content in “long-term” organic samples, such as wood, will provide the date of growth of the tree, rather than the date of the archaeological stratum in which the sample was found. Furthermore, wooden beams were reused in later strata, which can result in even greater differences in date. Since these “long-term” samples may introduce the “old wood” effect, any calculation of precise absolute dates based on “long-term” samples is unreliable and may easily lead to errors of up to several decades or even more. For this reason, researchers prefer to use “short-life” samples, such as seeds, grain or olive pits.
(2) Outliers. In many studies, particular radio-carbon dates are not considered valid because they do not match the majority of dated samples from the site in question. In other words the particular sample is either too late or too early No doubt the rejection of certain dates as “outliers” and their exclusion from the model may lead to different dates. Omitting outliers would be acceptable only so long as it is being done in a consistent, transparent way.
(3) Calibration. Radiocarbon years differ from calendar years because the former are dependent on the varying content of carbon-14 in the atmosphere. Therefore a complex procedure known as calibration has been developed, which converts radiocarbon test results to calendar years by relating these results to dendrochronologically dated tree-ring samples. The calibration curve is revised periodically as more data are continuously accumulated. But the absolute date after calibration depends on which calibration formula is used. The results, depending on the calibration, can be quite different.
(4) Standard deviation. Radiocarbon dates come with a given uncertainty. This uncertainty ranges from 20 years (for high-precision dating) through intermediate values of 50–100 years, and in some cases up to 100–150 years.
(5) Statistics. For interpreting the results, different statistical models are used by different researchers. Naturally, different statistical models for interpretation of the same data will produce different results.
(6) Other considerations. After processing the data with all these scientific tools, most archaeologists “improve” the given dates in accordance with broader archaeological and historical considerations.
For all these reasons, contrasting dates have been reached in the ongoing chronological debate concerning the Iron Age. A decisive solution is far from being accomplished. Based on the very same data, but employing different statistical methods, the various schools have reached quite diverse conclusions.
I do not mean to reject radiocarbon methodology for archaeological dating. But it is much more useful regarding broader archaeological periods. The differences in the various dates for the transition from Iron I to Iron IIa are too small to be helped much by radiocarbon dating.
Hopefully, as radiocarbon dating continues to develop, it will eventually be more useful in solving the problems of Iron Age chronology. But at present the use of this method for elucidating the problems of this period, in which the differences between the theories are so small, investment of this huge effort (hundreds of samples must be tested) does not contribute to our understanding of the chronological problems any more than the traditional cultural-historical methods, based on pottery chronology, etc. Moreover, as so much emphasis is put on questions of different calibration methods and different statistical manipulations, sometimes the archaeological evidence is neglected and the data are not properly presented.
The first stage in every discussion should be the proper presentation of the main archaeological finds—that is, stratigraphy and pottery. Based on the material finds it is possible to compare sites and regions and create a cultural-chronological horizon. In some cases today scholars are comparing radiocarbon dates, even before publishing the finds. The archaeological evidence is often not mentioned. Moreover, this archaeological evidence is not available and cannot be examined.
In short, radiocarbon is not the be-all and end-all of the problem. Let’s not ignore traditional archaeological dating methods.
“Archaeological Views: Carbon 14—The Solution to Dating David and Solomon?” by Lily Singer-Avitz originally appeared in Biblical Archaeology Review, May/June 2009. It was first republished in Bible History Daily on July 17, 2011.
Sign up to receive our email newsletter and never miss an update.