Michael G.L. Baillie, Bernd Becker, Bernd Kromer, Gordon W. Pearson, Jon R. Pilcher, Minze Stuiver, and Hans E. Suess— 1993 Pomerance Award for Scientific Contributions to Archaeology

Award Citation:

In the four decades since Willard Libby announced his Nobel Prize-winning discovery of the manner in which the radioactive isotope of carbon decays, few issues in archaeology, whether from the scientific or humanistic points of view, have been attended with as much heat. Initial reaction ranged from total rejection (V. Milojcic and S. Lloyd, to name two) to total acceptance, with predictable results. Indeed, for those who accepted radiocarbon dating as the final solution to all dating problems, their enthusiasm may have contributed to their dismay at the revision, several years later, of the half-life from 5,568 years to 5,730 years-a change of only 3% but enough to cause problems for some scholars but this was nothing compared to what was to follow.

In the early 1960s Hans Suess announced his "secular change in the radiocarbon time-scale," one component of which has been nicknamed the "Suess wiggles.'' Variation (i.e., the wiggles) in the production or intake of radioactive carbon by living organisms is the only one of Libby's original postulations that has been successfully challenged, but the understanding and resolution of this problem has taken 30 years of hard work to achieve. Interestingly, Libby himself resisted this modification to his schema.

The first generation of workers includes C. Wesley Ferguson, of the University of Arizona, who supplied the first set of dendrochronologically dated bristlecone pine samples; Paul Damon, also of Arizona, whose interest in the problem was spurred by its possible use as a surrogate for processes in solar physics, and who did one set of radiocarbon determinations; and Elizabeth Ralph and Henry Michael, of the Museum Applied Science Center for Archaeology (MASCA) at the University ofPennsylvania, who did the other. Ralph, Michael, and [Mark] Han's "Radiocarbon Dates and Reality," MASCA Newsletter (August 1973) was for years one of the most widely photocopied manuals in all of archaeological science. Beth Ralph was awarded the Pomerance Award by the AlA in 1986.

But problems still remained. From the point of view of the physicists, further fine-tuning was needed, and the underlying reasons for the variations still needed to be probed. From the point of view of the consumers of radiocarbon information, however, attitudes ranged from simple incomprehension, to skepticism, to utter disbelief and subsequent rejection. The bristlecone pine, this so-called "California shrub," which few people had ever seen, which grew at improbable altitudes, and had "missing rings," explicable enough to the workers in tree-rings but almost incomprehensible to those whose pet theories had been torpedoed by it, was not to be trusted, no matter how much hard work and good will had gone into its study. The gap between producer and consumer of archaeometric information loomed large. Although the physicists understood what was going on, the archaeological community generally did not, with a few notable exceptions. Colin Renfrew's book Before Civilization: The Radiocarbon Revolution and Prehistoric Europe, in which the preliminary implications of the "second radiocarbon revolution" are set forth, helped earn him a chair at Cambridge, but the unconverted still grumbled, some openly, others in private.

Thus, it was not until the building of a 7,272-year-long European oak tree-ring chronology (Pilcher, Baillie, Schmidt, and Becker in Nature 1984) and the advent of high-precision radiocarbon laboratories that all of this exploratory work could be built upon. The oak is a tree that all the suspicious consumers had seen and loved, with no missing rings, and from civilized altitudes and locales where the consumers themselves lived. The large rings allowed large samples to be taken with ample wood left over for replication. Moreover, the equipment had been developed, not without pain, to analyze it with error margins considerably below those of a decade earlier.

But even more importantly, half a dozen researchers, whom we now honor, put aside personal agendas and chances for individual glory and embarked on several years of interlaboratory and interdisciplinary collaboration, normally a thankless task. Three dendrochronologists-Jon Pilcher and Michael Baillie at the Centre for Palaeoecology, Queen's University, Belfast, and Bernd Becker at the Lehrstuhl für Botanik, Universität Hohenheim, Stuttgart-set about to reconcile the separate North Irish and German tree-ring chronologies into what is now a massive North European Oak Chronology, the longest continuous tree-ring record in the world, now over 10,000 years long. Then three physicists Minze Stuiver at the Institute of Geophysical and Planetary Physics, University of Washington, Gordon Pearson at the Centre for Palaeoecology; Queen's University, Belfast, and Bernd Kromer at Institut für Umweltphysik, Universität Heidelberg- collaborated in radiocarbon-dating the dated tree-rings that had been assembled. All this activity involved vast amounts of patience, interaction, error-checking, laboratory calibration and recalibration, and substantial amounts of travel, telephone, and telex money from their respective deans whom we should probably thank by separate letter. The sum of this effort is to be found in the Calibration Issue of the 12th International Radiocarbon Conference held in Trondheim, Norway, in June 85 and published as a Supplement to Radiocarbon 28 (1986). Amendments and extensions of some 10,000 years are reported in Radiocarbon 35: I (1993). Additionally, a new and revised version of the program CALIB is available from Professor Stuiver for the modest sum of $5.00.

It is a commonplace in archaeological awards or any other kind of award that we give lip service to the virtues of team efforts and then honor the efforts of single scholars. The Archaeological Institute of America gave Libby its Centennial Award in 1979, 30 years after his discovery of radiocarbon dating. Today we choose to honor six scholars: Baillie, Becker, Kromer, Pearson, Pilcher, and Stuiver, who banded together to get a big job done, plus their spiritual godfather, , Suess,* who had the idea that something was amiss in the first place. Indeed, it may be said that the younger members of this group joined forces in the first place to prove Suess wrong, but what Suess did with his "cosmic Schwung" they replicated and refined with years of good, hard work so that all but the hard-core skeptics have been forced to believe in calibration. In acknowledging their exemplary effort the Archaeological Institute of America applauds them and their colleagues and staff, individually and collectively, and looks forward to the refinements in our knowledge of the ancient past that will be brought about by their collaboration.

 

*Hans E. Suess died in September I 993 before he could be informed of the Pomerance Award.

 

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