Collagen Fingerprinting: A New Screening Technique for Radiocarbon Dating Ancient Bone

Abstract

Collagen is the dominant organic component of bone and is intimately locked within the hydroxyapatite structure of this ubiquitous biomaterial that dominates archaeological and palaeontological assemblages. Radiocarbon analysis of extracted collagen is one of the most common approaches to dating bone from late Pleistocene or Holocene deposits, but dating is relatively expensive compared to other biochemical techniques. Numerous analytical methods have previously been investigated for the purpose of screening out samples that are unlikely to yield reliable dates including histological analysis, UV-stimulated fluorescence and, most commonly, the measurement of percentage nitrogen (%N) and ratio of carbon to nitrogen (C:N). Here we propose the use of collagen fingerprinting (also known as Zooarchaeology by Mass Spectrometry, or ZooMS, when applied to species identification) as an alternative screening method for radiocarbon dating, due to its ability to provide information on collagen presence and quality, alongside species identification. The method was tested on a series of sub-fossil bone specimens from cave systems on Cayman Brac (Cayman Islands), chosen due to the observable range in diagenetic alteration, and in particular, the extent of mineralisation. Six 14C dates, of 18 initial attempts, were obtained from remains of extinct hutia, Capromys sp. (Rodentia; Capromyidae), recovered from five distinct caves on Cayman Brac, and ranging from 393 ± 25 to 1588 ± 26 radiocarbon years before present (yr BP). All of the bone samples that yielded radiocarbon dates generated excellent collagen fingerprints, and conversely those that gave poor fingerprints also failed dating. Additionally, two successfully fingerprinted bone samples were screened out from a set of 81. Both subsequently generated 14C dates, demonstrating successful utilisation of ZooMS as an alternative screening mechanism to identify bone samples that are suitable for 14C analysis.

Identifying remains of extinct kangaroos in Late Pleistocene deposits using collagen fingerprinting

“…Additionally, the method can easily be applied to a wide range of vertebrate taxa worldwide and although more useful in identifying fragmentary bone that cannot be identified morphologically, in cases with morphologically similar taxa such as this, or with sheep/goat (Buckley et al ., ; Buckley and Kansa, ), the approach could be much more cost‐effective and, at times, more reliable than hiring a specialist morphologist; depending on sample size, these analyses can also leave the remains morphologically intact so that future investigations can be carried out on the fragmentary assemblage. The method is also highly complementary with other archaeological science methods that are based on collagen extraction, such as radiocarbon dating (Harvey et al ., ) and stable‐isotope analysis (van der Sluis et al , ). Investigators could utilize the combined approaches to better understand the palaeoecology of particular regions with improved chronologies of particular taxa.…”

Species identification and decay assessment of Late Pleistocene fragmentary vertebrate remains from Pin Hole Cave (Creswell Crags, UK) using collagen fingerprinting

“…Although the more appropriate approach would clearly be the use of radiocarbon ( 14 C) dating, the majority of microfaunal bone fragments are typically too small. Additionally, assuming that the bone specimens were large enough for dating, this remains a pursuit that is orders of magnitude more costly where ZooMS collagen fingerprint analysis can identify samples that are ideal for collagenbased 14 C dating (Harvey et al 2016) from large assemblages such as seen in Pin Hole Cave.…”

Collagen deamidation in archaeological bone as an assessment for relative decay rates

“…) and has also been suggested as a reliable screening method for radiocarbon dating (Harvey et al . ). However, collagen from archaeological bones often undergoes extensive degradation.…”