Our attention was drawn to a recent paper just out online by D’Errico and Banks in Quaternary Science Reviews called “Tephra studies and the reconstruction of Middle-to-Upper Paleolithic cultural trajectories” and in particular a sentence in it that refers to our work here in Oxford over the last decade developing and applying more robust methods of pretreatment chemistry to the radiocarbon dating of the Palaeolithic. They say:
“Our recent experiences (Banks et al., 2013b) suggest that while it is true that the use of ultrafiltration and ABOx- SC methods produce accurate and robust ages, it is not true that such ages are significantly older than previous ones; more often than not, or at least as frequently, new ages confirm previously obtained ones”.
The many publications we have produced say the polar opposite and show that there are many problems with previously obtained chronometric data. Usually the previous dates are a lot younger than the new determinations, in contrast to what D’Errico and Banks say.
When we first started working in Italy, a paper by Sarah Milliken (1999, Oxford Journal of Archaeology) had just been published which contained a summary diagram of the chronometric data pertaining to the Italian Palaeolithic (see below for picture). There were 4 radiocarbon dates from the Uluzzian sites of Italy, every one of which is erroneously young, at around ~30,000 BP. Our new determinations for the Uluzzian put it at 35-40,000 BP (Douka et al. 2014). At Fumane we redated the sequence (Higham et al. 2009) and showed that more than 70% of the previous determinations from the site were inaccurate. The previous dates from the Uluzzian levels at that site were in agreement with one another at 33,000 BP but our new dates were 41-42,000 BP. The new results we obtained didn’t confirm the old dates, they showed that they were not correct, by almost 10,000 years. Similar statistics emerge from other sites that we have examined over the last decade. In Spain, we showed (Wood et al., 2012 PNAS) showed that the previous chronology from the south of Iberia was not supported by new determinations. In one instance, a determination from Zafarraya that was 33,000 BP turned out to be >46,000 when dated using ultrafiltration.
Despite this, D’Errico and Banks state that overall the new ages just confirm what they already knew from sites in Italy and in Europe more widely. It is exceedingly difficult, however, to look back at a corpus of radiocarbon dates obtained before ~2000, or even more recently in some cases, and say categorically “This determination is accurate”. It’s not possible to do because 99% of the time there is not the analytical data associated with the radiocarbon date that allows some confidence to be expressed in the result, particularly if the date is on bone collagen. Ideally, we want %collagen values and yield, carbon to nitrogen atomic ratios, stable isotope values, %C on combustion, allied with robust methods of chemical pretreatment and the use of background standards being run at the same time as the radiocarbon samples. The vast majority of old dates don’t have any of this data in support of it so it is not possible to say with a high degree of certainty whether a date is right or not. In our experience, most of the time, they’re not.
Our work has robustly tested the existing dataset of chronometric data and found significant problems. Providing improved radiocarbon data leads to new interpretations of the chronology of the Middle and Upper Palaeolithic.
The d'Errico/Banks paper can be found here.