A mass grave found in the area of La Pedraja, Spain, with the bodies of people killed during Spain’s Civil War (1936-1939) contained preserved brains of 45 people.

The mass grave of around 104 individuals was located on a hillside in the northern province of Burgos. It is one of hundreds of mass graves from the war and from ensuing decades of dictatorship under General Francisco Franco, of which only a few have been dug up. Very specific environmental conditions have allowed for preservation of the brain tissue – heavy rain has poured into bullet holes and turned the tissue in a soap-like substance. Along these organs archaeologists were able to unearthed a preserved heart of one of the individuals.

The researchers believe that this is the largest collection of naturally preserved brains in the world, as such finds are rare and only 100 documented cases are known around the world. Specialists were able to identify only 16 of over hundred of the unearthed individuals. The brains are being kept in a laboratory in Galicia, northwestern Spain.

(after Reuters & Juan Medina)