Bone need not remain an elephant in the room for radiocarbon dating

Abstract

Radiocarbon ( 14 C) analysis of skeletal remains by accelerator mass spectrometry is an essential tool in multiple branches of science. However, bone 14 C dating results can be inconsistent and not comparable due to disparate laboratory pretreatment protocols that remove contamination. And, pretreatments are rarely discussed or reported by end-users, making it an ‘elephant in the room’ for Quaternary scientists. Through a questionnaire survey, I quantified consensus on the reliability of collagen pretreatments for 14 C dating across 132 experts (25 countries). I discovered that while more than 95% of the audience was wary of contamination and would avoid gelatinization alone (minimum pretreatment used by most 14 C facilities), 52% asked laboratories to choose the pretreatment method for them, and 58% could not rank the reliability of at least one pretreatment. Ultrafiltration was highly popular, and purification by XAD resins seemed restricted to American researchers. Isolating and dating the amino acid hydroxyproline was perceived as the most reliable pretreatment, but is expensive, time-consuming and not widely available. Solid evidence supports that only molecular-level dating accommodates all known bone contaminants and guarantees complete removal of humic and fulvic acids and conservation substances, with three key areas of progress: (i) innovation and more funded research is required to develop affordable analytical chemistry that can handle low-mass samples of collagen amino acids, (ii) a certification agency overseeing dating-quality control is needed to enhance methodological reproducibility and dating accuracy among laboratories, and (iii) more cross-disciplinary work with better 14 C reporting etiquette will promote the integration of 14 C dating across disciplines. Those developments could conclude long-standing debates based on low-accuracy data used to build chronologies for animal domestications, human/megafauna extirpations and migrations, archaeology, palaeoecology, palaeontology and palaeoclimate models.

Radiocarbon dating

“…The interdisciplinary applications of radiocarbon dating have also resulted in a number of thematic databases representing the archaeology of specific regions or time periods [341][342][343] , dates of volcanic eruptions 344 and ages of soils 345 , bones 346 , or seafloor sediments 347 . There are also databases that include radiocarbon dates as a part of extensive data sets in the compilation of climatic records from around the globe 348 (also see Supplementary Table 3).…”

Comparing Analysis of Pretreatment Methods of Wood and Bone Materials for the Chronology of Peripheral Burials at Tunnug 1, Tuva Republic, Russia

“…The preparation for 14 C dating of bones has been extensively discussed in the literature (Higham et al 2006;Fuller et al 2014;Herrando-Pérez 2021). The most common discussion is dedicated old bones yielding 14 C dates which are younger than expected (e.g., Higham et al 2006).…”

Retreatment of Bone Material in the Gliwice Radiocarbon Laboratory Using Ultrafiltration

“…Additionally, some experiments to date the bioapatite fraction have been proved successful (e.g., Cherkinsky 2009). For an overview of methods used for preparation bones for 14 C dating see Herrando-Pérez (2021).…”