Minimally Destructive Radiocarbon Dating of Bone

Bone is commonly used in radiocarbon dating in archaeology and other disciplines. Despite advances in collagen extraction protocols, the process remains destructive, requiring sawing, drilling or crushing of bone material. While non-destructive approaches have recently been applied in ancient genomics and palaeoproteomics, no equivalent approach has been established for radiocarbon dating of bone. We explored whether this is possible using a series of experiments.

We experimented by using a water-based approach to extract soluble collagen from whole bone and teeth samples. We heated the samples in hot (75°C and 90°C) water for several hours. We obtained the soluble collagen fraction of the bone and purified and AMS dated the extracts. We used standard reference bones and samples from archaeological sites.

We found that the amino acid composition, C/N atomic ratios, δ¹³C and δ¹⁵N values of the hot-water-extracted soluble collagen were comparable to collagen isolated from the same bones using classic Longin collagen methods. Bone and teeth from Bronze Age and Middle and Upper Paleolithic sites, which had been dated previously using routine destructive methods that involved acid demineralization, yielded dates on the water-soluble fraction that were in good agreement with these earlier results.

We show that a minimally destructive collagen extraction, coupled with an additional purification step such as ultrafiltration or XAD-2 purification, yields identical radiocarbon ages to those obtained via the routine destructive methods, but without any visible external damage. The method may allow us in future to date precious artefacts, ornaments and museum objects without significant alteration.