Suspicious minds: a molecular taphonomic approach to preservation of the central nervous system in the archaeological and fossil records

Over 1800 human brains have been unearthed by archaeologists, and more than 390 putative neural tissues have been identified in fossils as old as the Cambrian Period. These preserved neural tissues provide unique insights into the palaeobiology and evolutionary history of extinct taxa; for example, the development of chemical and electrical signalling systems (neural precursors) during the early radiation of metazoa.

However, decay experiments suggest that the central nervous system (CNS) is amongst the first organs to decompose post-mortem, and there is no known pathway to fossilisation accounting for their preservation. What permits the exceptional preservation of the CNS over other, more decay-resistant soft tissues?

Taphonomy, the study of how organic matter passes from the biosphere to the lithosphere, recognises that the chemistry of fossil soft tissues is critical for elucidating preservation processes; yet