Brain tissue from 2500-year-old skull analysed by Raman spectroscopy

Brain tissue that survived in a 2500-year-old skull that was excavated in 2008 has been analysed by Raman spectroscopy, to show degraded protein and the results of cyanobacterial degradation. The Heslington brain was found in a waterlogged pit near York, UK, and was radiocarbon dated to 673-482 BC. It belonged to a 26-45-year-old man and the observable damage was consistent with hanging followed by careful decapitation.

Yellow, convoluted material discovered in the skull brain was deduced to be brain mass and small amounts were removed for analysis, as described by Howell Edwards from the University of Bradford, UK in Journal of Raman Spectroscopy. Earlier studies revealed the remains of myelin structures that were detected by electron microscopy and there appeared to be no putrefaction. There was little residual protein, no cholesterol and no phospholipids but microbial degradation products of cholesterol and lipids were found.

Now, Raman spectroscopy was applied to the brain tissue in the first study of its type. This technique identified degraded protein which was consistent with a naturally preserved brain. In addition, the presence of carotenoids and the cyanobacterial protective compound scytonemin in the brain tissue and the surrounding sludge was consistent with long-term burial under wet conditions and might indicate microbiological preservation of the brain tissue.

The spectra from a lab-based instrument and a portable Raman spectrometer were identical, the poorer resolution of the latter having no effect on the results. The research team note that use of a portable instrument in archaeological work will allow on-site screening to give preliminary data before deciding on further study in the lab.

[Image: © York Archaeological Trust]