A very rare archaeological find—a spontaneously mummified human brain—will shed light on the genetic and social history of Bronze Age humans.

We’ve all heard of brains being “baked” or “fried,” usually in reference to drug abuse. But a boiled brain, preserved for 4,000 years?

Apparently that’s what happened in Turkey, said Dr. Meriç Altinöz of Halic University in Istanbul. Altinöz and other researchers report their analysis of four ancient human brains found in a Bronze Age settlement in western Turkey in the current edition of HOMO – Journal of Comparative Human Biology.

Altinöz told Healthline he believes an earthquake and subsequent fire transpired in the settlement where archaeologists unearthed the brains. Basically, the brains were buried and deprived of oxygen, while the heat from the fire caused them to cook inside their skulls.

The result was a remarkable preservation process called “spontaneous mummification,” Altinöz said, of which there have only been about a dozen reports since 1857.

“Two of these articles were dealing with modern samples found in an African bushveld and in an Bulgarian mass grave. Other samples were archaeological specimens, which were 500 to 8000 years old,” Altinöz said.

But since archaeologists don’t typically open fossilized skulls to look inside, brain tissue may be preserved more often than we think, Altinöz added.

Other recorded cases of spontaneous mummification were not the result of boiling. In fact, the process can occur in a variety of ways. “Though our brain samples are not the oldest, they are very unique in many aspects,” Altinöz said. “In other samples of spontaneous mummification, samples were mummified either in glaciers, due to freezing; bog sediments, likely due to toxic tannins of putrefied plants, which exerted anti-bacterial actions; and in deserts, due to dehydration.”

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