Radiocarbon dating

Radiocarbon (¹⁴C) dating introduced by Arnold and Libby (1949) was one of the most significant leaps in the history of archaeology, history and the history of art. This technique allows scientists to estimate the absolute date of death of any organism. Using the isotopic ratios of the radioactive carbon-14 and stable carbon-12 in the organism’s tissues and comparing it to the ratio in Earth’s atmosphere permits to calculate how long it was since the organism stopped exchanging carbon with its surrounding. Further developments in the field included the introduction of the calibration process in order to account for the fluctuations of the ¹⁴C/¹²C ratio in the atmosphere through time, and the use of mass spectrometry (MS) to arrive at more precise measurements using smaller samples (Bayliss 2009). The most recent important addition to the ¹⁴C dating methodology is the use of Bayesian modelling (Bronk Ramsey 2009) - a series of statistical tools which help to incorporate additional information (e.g. archaeological, historical, textual) into the absolute chronology, effectively reducing the errors of the radiocarbon dates.

For more than a century now, chronologies of the Mesopotamian civilisations were devised using primarily historical (written accounts) and archaeological methods (development of material culture). Although the need for the inclusion of scientific methods into the construction of absolute chronologies was recognised decades ago (Mellaart 1979; Bruins & Mook 1989), relatively few improvements in this direction have been made. Radiocarbon dating of Mesopotamian material is problematic for a number of reasons:

- The availability of radiocarbon dating samples has been a long-standing issue in the study of Mesopotamian chronology. Most of the available material came from excavations conducted during the late 19^th and early 20^th century. Due to social and political instabilities in the region, few new excavations were conducted. - Radiocarbon measurements can only be seen as reliable sources of chronological informations if they were conducted on material from properly excavated and documented archaeological contexts. Information about these is often lacking, especially in the case of important Mesopotamian sites (Ur, Kish, Uruk, etc.). - The nature of the material has significant impact on the reliability of the radiocarbon date. Short-lived plants and textiles (twigs, textiles etc.) and bones are more likely to produce precise and accurate absolute dates than long-lived materials (e.g. shells, wood) or charcoal. - A plateaus in the calibration curve, i.e. periods of increased production of ¹⁴C in the Earth’s atmosphere, can cause the errors of the radiocarbon dates to increase drastically, obscuring the absolute chronology. One such period occurred during the Early Dynastic era, between ca. 2820-2580 BC (Reimer et al. 2012). This problem can only be alleviated with the production of new radiocarbon dates.

Below is a list of some important publications dealing with the issues of radiocarbon dating of Ancient Mesopotamian sites. An ongoing PhD project is aiming to synthesise the available ¹⁴C dates in their archaeological and textual context in order to produce more reliable absolute chronologies:

1. Barker, H., J. Mackey 1963 British Museum Radiocarbon Dates Measurements IV. Radiocarbon 5: 104-108
2. Boehmer, R.M. 1991 14C-Daten aus Uruk und Abydos - Ägytisches (?) im Frühen Nordsyrien, Sumer und Elam. Baghdader Mitteilungen 22: 223-230
3. Bruins, H.J., J. van der Plicht, W.G. Mook 1991 Establishing calibrated 14C chronologies; problematic time zones and high-precision dating with reference to Near Eastern archaeology. Radiocarbon 33/2: 183-184
4. Bruins, H.J. 2001 Near East Chronology: Towards an Integrated Approach. Radiocarbon 43/3: 1147-1154
5. Ess, M. van 2013 Neue Radiokarondatierungen aus Uruk. In Crüsemann, N., M. van Ess, M. Hilgert, B. Salje (eds) Uruk: 5000 Jahre Megacity. Petersburg: Reiss-Engelhorn-Museen
6. Mellaart, J. 1979 Egyptian and Near Eastern chronology: a dilemma? Antiquity 53/1: 6-19
7. Plicht, J. van der, H.J. Bruins 2001 Radiocarbon Dating In Near-Eastern Contexts: Confusion And Quality Control. Radiocarbon 43/3: 1155-1166
8. Porada, E.D., D.P. Hansen, S. Dunham, S.H. Babcock 1991 The Chronology of Mesopotamia, ca. 7000-1600 B.C. In R.W. Ehrich (ed.) Chronologies in Old World Archaeology. Chicago: The University of Chicago Press
9. Postgate, J.N. 1977 Excavations at Abu Salabikh, 1976. Iraq 39: 269-299
10. Stuckenrath, R.Jr. 1963 University of Pennsylvania Radiocarbon Dates VI. Radiocarbon 5: 82-103
11. Stuckenrath, R.Jr. 1965 University of Pennsylvania Radiocarbon Dates VIII. Radiocarbon 7: 187-191
12. Wright, H.T. 1980 Problems of absolute chronology in protohistoric Mesopotamia Paléorient 6/6: 93-98.
13. Wright, H.T., E.S.A. Rupley 2001 Calibrated Radiocarbon Age Determinations of Uruk-Related Assemblies. In E. Rothman (ed.) Uruk, Mesopotamia & Its Neighbours: Cross-Cultural Interactions in the Ear of State Formation. Santa Fe: SAR

1. Arnold J.R., W.F. Libby 1949. Age determinations by radiocarbon content: checks with samples of known age. Science 110(2869):678–80.
2. Bayliss, A. 2009 Rolling out Revolution: Using Radiocarbon Dating in Archaeology. Radiocarbon 51/1: 123-147
3. Bronk Ramsey, Ch. 2009a Bayesian Analysis of Radiocarbon Dates. Radiocarbon 51/1: 337-360
4. Bruins, H.J, W.G. Mook 1989 The Need for a Calibrated Radiocarbon Chronology of Near Eastern Archaeology. Radiocarbon 31/3: 1019-1029
5. Reimer, P.J., E. Bard, A. Bayliss, J. W. Beck, P.G. Blackwell, Ch. Bronk Ramsey, C.E. Buck, H. Cheng, R.L. Edwards, M. Friedrich, P.M. Grootes, T.P. Guilderson, H. Haflidason, I. Hajdas, Ch. Hatté, T.J. Heaton, D.L. Hoffmann, A.G. Hogg, K.A. Hughen, K.F. Kaiser, B. Kromer, S.W. Manning, M. Niu, R.W. Reimer, D.A. Richards, E. Scott, J.R. Southon, R.A. Staff, Ch.S.M. Turney, J. van der Plicht 2012 IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP. Radiocarbon 55/4: 1869-1887