Human brains found in a fire-affected 4000-years old Bronze Age tumulus layer rich in soil alkalines and boron in Kutahya,Western Anatolia

Undecomposed human bodies and organs always attracted interest in terms of understanding biological tissue stability and immortality. Amongst these, cases of natural mummification found in glaciers, bog sediments and deserts caused even more attention. In 2010, an archeological excavation of a Bronze Age layer in a tumulus near the Western Anatolia city Kütahya revealed fire affected regions with burnt human skeletons and charred wooden objects. Inside of the cracked skulls, undecomposed brains were discernible. To analyze the burial taphonomy of the rare phenomenon of brain preservation, we analyzed brains, bone, teeth and surrounding soils elements using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Adipocere formation or saponification of postmortem tissue fat requires high levels of alkalinity and especially potassium. Indeed, ICP-MS analysis of the brain, teeth and bone and also of the surrounding soil revealed high levels of potassium, magnesium, aluminum and boron, which are compatible with the famous role of Kütahya in tile production with its soil containing high level of alkalines and tile-glazing boron. Fatty acid chromatography revealed simultaneous saturation of fats and protection of fragile unsaturated fatty acids consistent with soil-presence of both pro-oxidant and anti-oxidant trace metals. Computerized tomography revealed protection of diencephalic, metencephalic and occipital tissue in one of the best-preserved specimens. Boron was previously found as an intentional preservative of Tutankhamen and Deir el Bahari mummies. Here, in natural soil with its insect-repellant, anti-bacterial and fire-resistance qualities it may be a factor to preserve heat-affected brains as almost bioporcellain specimens.