Radiocarbon Dating Ancient Grease

20 years ago, radiocarbon dating was transformed by the widespread adoption of AMS analysis, accelerator mass spectroscopy. Willard Libby's original scintillation-counting method demanded large sample sizes and a lot of time per sample. The sample size meant that many interesting things couldn't be dated at all, and that once you had gotten a large enough chunk of organic material together, chances were that it would be heavily contaminated with later stuff. The time demands meant that prices were high.

Radiocarbon technology continues to advance. A few years back, I learned that a method had been perfected whereby cremated bone could be dated accurately. Hugely useful in Scandinavia where cremation was the rule for 2000 years until the introduction of Christianity. And now a paper (behind a pay wall) by R. Berstan et al. in the forthcoming issue of Antiquity describes a method to date lipids extracted from pottery! Ancient grease!

Neolithic scholars have been dating burnt food crusts from the surface of potsherds for years. Ideally, you find a characteristically decorated sherd with a lot of gunk on it, and then radiocarbon nails down a part of your pottery style chronology in calendar years. The problem is that most sherds with characteristic decoration have no food crust. But they do retain grease within their ceramic matrix. I expect this technique to become a big hit.

Update 11 September: Explains my buddy Ludvig Papmehl-Dufay,

"Cool stuff indeed. I haven't read the paper, but I don't think it's such a big breakthrough: the same team (largely) published a similar study five years ago.

Stott, A. W., Berstan, R., Evershed, R. P., Bronk-Ramsay, C., Hedges, R. E. M. & Humm, M. J. 2003. Direct dating of archaeological pottery by compound-specific 14C analysis of preserved lipids. Analytical chemistry 2003:75, pp. 5037-5045.

[More blog entries about , , ; , , .]


More like this

So I spent the day on GÃ¥lö, happily digging & sieving a square meter on a Middle Neolithic shore site 25 meters above current sea level that my friend Roger found two years ago. I haven't dug that period since 1993 when I spent almost the entire fieldwork season on the classic Bollbacken…
As discussed here repeatedly before, the eastern coast of Sweden is in continual flux because of post-glacial shoreline displacement. Since the inland ice melted away and relieved its pressure on the land over 10 000 years ago, the dent made by the ice has been rebounding: first very quickly, then…
Archaeology Magazine's May/June issue (63:3) has a good long feature by Jarrett A. Lobell & Samir S. Patel on North European bog bodies including some new finds: Lower Saxony in 2000, the Hebrides in 2001 (you may have heard about the weird re-interred bog bodies found under a Bronze Age house…
If you have a lot of samples lying around that you want to run through AMS radiocarbon analysis, then get thee to the Poznan lab's informative web site. Tomasz Goslar tells me he's offering a summer bargain. The standard price is €320 / $430 / £220 plus sales tax per carbon sample, with an…

What about glazed pottery? It seems to me the glassy surface would greatly reduce the amount of grease retained.

Glazed pottery is a modern thing. Any stratification containing such pottery must be bulldozed away on sight, with extreme prejudice, to the hilt. It cannot be allowed to pollute our sites.

Die, glazed pottery.

Indeed, glazed pottery is a profanity. That said, there are some pretty old usages of glazing in the Mediterranean, but mostly only on the outside. You don't waste expensive glazing where it is not seen.

AMS-technology that helps us study even extremely small samples is the best thing to happen to archaeology since Libby first had his blessed realization. It's a giant leap forward for prehistoric studies (which is all that really matters of course)

I view modern society and science as a kind of substrate for our work. Most of what you see around you, most people in the world, are just sort of an operating system. And it's running a single application: prehistoric archaeology.