These boots are made for burnin': Inferring the position of the corpse and the presence of leather footwears during cremation through isotope (δ13C, δ18O) and infrared (FTIR) analyses of experimentally burnt skeletal remains

PLoS One. 2021 Oct 13;16(10):e0257199. doi: 10.1371/journal.pone.0257199. eCollection 2021.

Abstract

Cremation is a complex mortuary practice, involving a number of activities of the living towards the dead before, during, and after the destruction of the bodily soft tissues by fire. The limiting information concerning these behavioral patterns obtained from the pyre remains and/or cremation deposits prevents the reconstruction of the handling of the corpse during the burning process. This pioneering study tries to determine the initial positioning of the corpse in the pyre and assess whether the deceased was wearing closed leather shoes during cremation through isotopic (δ13C, δ18O) and infrared (ATR-FTIR) analyses of experimentally burnt pig remains, used as a proxy for humans. The results obtained show that both the position of feet on or within the pyre and the presence of footwears may moderately-to-highly influence the oxygen isotope ratios of bone apatite carbonates and the cyanamide content of calcined bone in certain situations. By forming a protective layer, shoes appear to temporarily delay the burning of the underlying pig tissues and to increase the heat-shielding effect of the soft tissues protecting the bone mineral fraction. In such case, bioapatite bone carbonates exchange oxygen with a relatively more 18O-depleted atmosphere (due to the influence of lignin-derived oxygen rather than cellulose-derived oxygen), resulting in more pronounced decrease in the δ18Ocarb values during burning of the shoed feet vs. unshoed feet. The shift observed here was as high as 2.5‰. A concomitant isotopic effect of the initial location of the feet in the pyres was also observed, resulting in a top-to-bottom decrease difference in the δ18Ocarb values of shoed feet of about 1.4‰ between each deposition level tested. Finally, the presence of cyanamide (CN/P ≥ 0.02) seems to be indicative of closed footwear since the latter creates favorable conditions for its incorporation into bone apatite.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Remains / chemistry
  • Bone and Bones / chemistry
  • Cadaver
  • Carbon Isotopes / analysis
  • Cremation*
  • Humans
  • Oxygen Isotopes / analysis
  • Shoes
  • Spectroscopy, Fourier Transform Infrared
  • Swine

Substances

  • Carbon Isotopes
  • Oxygen Isotopes
  • Oxygen-18
  • Carbon-13

Grants and funding

This research is part of the CRUMBEL project (“CRemations, Urns and Mobility: ancient population dynamics in BELgium”), funded by Fonds Wetenschappelijk Onderzoek – Vlaanderen (FWO) and the Fonds de la Recherche Scientifique (F.R.S.-FNRS) within the framework of the Excellence of Science (EoS) program in Belgium (30999782). FNRS and FWO also provided support in the form of doctoral fellowships awarded to AS, MH, and ES, as well as a postdoctoral fellowship awarded to CS. Research Foundation Flanders (FWO – Hercules Program) provided support in the form of an upgrade to the stable isotope laboratory through grants awarded to PC (HERC9, HERC46) and the acquisition of ATR-FTIR instrumentation through a grant awarded to PC (HERC35).