Experimental chemical degradation compared to natural diagenetic alteration of collagen: implications for collagen quality indicators for stable isotope analysis

Abstract

Stable isotopic ratios from archaeological bone collagen are valid palaeodietary indicators, but depend on sufficiently well preserved molecules and several collagen quality criteria have to be fulfilled (mostly collagen wt%, C%; N%, C/N molar ratio). For a reassessment of these quality criteria, and a better understanding of the chemical degradation of bone collagen, experimentally degraded modern bones and 54 archaeological human bones were investigated. In the course of the experimental degradation, alterations of isotopic ratios were paralleled by altered collagen quality criteria. The contrary was found in the case of the archaeological specimens. This implies that the commonly used collagen quality criteria may be insufficient and do not guarantee that stable isotopic values of the gelatine extracts will still represent the original biological signal.

A brackish water aquatic foodweb: trophic levels and salinity gradients in the Schlei fjord, Northern Germany, in Viking and medieval times

“…De Niro and Weiner, 1988;Nicholson, 1998). In experimentally degraded mammalian bone, Harbeck et al (2006) and Harbeck and Grupe (2009) found the stable isotopic ratios in the extractable gelatine unaltered although the molar C/N ratios even slightly exceeded 4.0 (4.17). Therefore, the C/N ratio is not necessarily Table 5.…”

Fish bone chemistry and ultrastructure: implications for taphonomy and stable isotope analysis

“…To date, a number of studies have attempted to define and refine such criteria (Ambrose, 1990;DeNiro, 1985;DeNiro and Weiner, 1988;Dobberstein et al, 2009;Grupe and Turban-Just, 1998;Grupe et al, 2000;Harbeck and Grupe, 2009;Schoeninger et al, 1989;Tuross et al, 1988Tuross et al, , 1989van Klinken, 1999), but all have focused exclusively on mammalian bone. One notable exception is the work of Nehlich and Richards (2009), who suggested that because of differences in the amino acid composition of collagen, the quality criteria for sulfur isotopic analysis (C:S ratio) should be different for fish and mammalian bone.…”

The effects of Paraloid B‐72 and Butvar B‐98 treatment and organic solvent removal on δ13C, δ15N, and δ18O values of collagen and hydroxyapatite in a modern bone

“…Postmortem diagenesis, contamination, or addition of laboratory chemicals and consolidants might alter the isotopes from their original state, thus invalidating interpretations based on these values. While well-established methods exist to monitor postmortem diagensis and contamination of buried bones (DeNiro, 1985;Tuross et al, 1989;Ambrose, 1990;Ayliffe et al, 1994;Hedges et al, 1995;Person et al, 1995;Iacumin et al, 1996;Koch et al, 1997;Lecuyer at al., 1999;van Klinken, 1999;McNulty et al, 2002;Harbeck et al, 2009), the effects of solvents and consolidants on isotope values is less wellunderstood.…”