A large-scale evaluation of intraperson isotopic variation within human bone collagen and bioapatite

This study investigated intraperson skeletal (herein referred to as either intraperson or intraskeletal ) variation in stable isotope ratios for collagen (C and N) and bioapatite (C and O) extracted from five to six long bones from 27 modern individuals. The maximum intraperson variation observed for collagen was 0.78%o for delta(13)Ccoll values and 1.12%o for delta(15)Ncoll values, with a mean variation ( +/- SD) of 0.33 +/- 0.18%o and 0.45 +/- 0.27%o, respectively. For bioapatite, the maximum intraperson variation was 1.63%o for delta(13)Cap values and 4.80%o for delta(18)Oap values, with a mean variation ( +/- SD) of 0.81 +/- 0.32%o and 1.00 +/- 1.03%o, respectively. These results generally agree with previously reported data on intraskeletal isotopic variation. Using a two-and three-standard-deviations-from-the-mean model with analytical quality control data included, it is proposed that two bones with differing collagen delta(13)Ccoll values greater than 0.75%o are probably from dif-ferent individuals, and those that have differing values greater than 0.95%o are from different individuals. Likewise, differing collagen delta(15)Ncoll values greater than 1.05%o are probably different, and greater than 1.35%o are different. For bioapatite, the proposed values change to 1.55%o and 1.90%o for delta(13)Cap, respectively; for delta(18)Oap values no limits were set due to the unexpectedly large variation found in the study population. We highly encourage researchers to use extreme caution when interpreting delta O-18 values from bone apatite. We also note that these parameters were evaluated on modern samples and therefore may not reflect in-traperson variation in past societies. Finally, we demonstrate application of these interpretative limits to sort commingled human remains cases.Published by Elsevier B.V.

Automated summary

This study investigated the intraperson skeletal variation in stable isotope ratios extracted from long bones of 27 modern individuals. The results showed that collagen and bioapatite have variations within individuals, which align with previous studies. The study also proposed limits for determining different individuals based on the differences in isotope values. Additionally, caution is advised when interpreting delta O-18 values from bone apatite, and the study's results may not fully reflect historical intraperson variation.