Mysterious preserved human brains found after thousands of years including 12,000-year-old specimen baffling scientists

"Here, we collated an archive of more than 4400 human brains preserved in the archaeological record across approximately 12 000 years, more than 1300 of which constitute the only soft tissue preserved amongst otherwise skeletonized remains.

"We found that brains of this type persist on time scales exceeding those preserved by other means, which suggests an unknown mechanism may be responsible for preservation particular to the central nervous system," the researchers wrote.

One of the oldest brains in question was found preserved in a severed skull.

The skull belonged to a Stone Age person who had been decapitated and their head placed on spike in Sweden sometime between 6350 to 5000 BC.

Another of the brains was found in a prehistoric cemetery in Upper Egypt and had been preserved in a shallow sandy grave.

"The untapped archive of preserved ancient brains represents an opportunity for bioarchaeological studies of human evolution, health and disease," the researchers continued.

Some of the preserved brains had resonable explanations such as being freeze dried or volcanic preservation.

However, there were many that were the only soft tissue to survive on skeletons.

Scientists warned that preserved brains can look the same color as soil and many may have been discarded during excavations.