Studies of human brains that have been naturally preserved for hundreds or thousands of years have identified 1,300 cases in which the organ survived when all other soft tissue had decomposed. Some of these brains are over 12,000 years old.

“This type of brain is the only one with preserved soft tissue and has been found in sunken ships and flooded graves with only floating bones.” alexandra morton hayward at Oxford University. “It's really, really weird.”

“To be honest, we don't expect the brain to be preserved in any environment,” she says. “As an archaeologist, if you were to dig a grave and find a brain rattling inside a skull, you would be shocked. But you don't expect soft tissue to be preserved, especially in a waterlogged environment. yeah.”

Morton-Hayward first became interested in brain preservation while working as a mortician. “The brain is known to be one of the first organs to decompose after death. I saw it liquefy pretty quickly. But I also saw it preserved.” she says.

Many researchers point out that the human brain is preserved more often than expected and in surprising circumstances, says Morton-Hayward. Now, she and her colleagues are conducting the first-ever systematic study of this phenomenon. They compiled a database of more than 4,400 preserved human brains found around the world.

They also collected and studied many preserved brains themselves. “We actually put it in an MRI machine, and that was a terrible mistake. We didn't know how much iron was in there,” says Morton Hayward.

In most cases, brain preservation can be explained by known processes. For example, the brains of sacrificial Incas buried atop volcanoes in South America around 1450 AD were freeze-dried along with the bodies, Morton-Hayward said.

2,400 years ago, the bodies and brains of swamp people like Tollundman, who was hanged and dumped in a swamp in what is now Denmark, were preserved through a tanning process similar to that used for leather.

Saponification, in which fatty substances are turned into a soap form called grave wax, also preserved the brains of some people who were shot and buried in mass graves in 1936 during the Spanish Civil War.

However, the known process preserves all soft tissue, not just the brain. They do not account for the 1300 cases in which the brain is the only surviving soft tissue.

“This unknown mechanism is completely different,” says Morton-Hayward. “The key feature of this device is that only the brain and bones remain. There is no skin, no muscle, and no intestines.”

For example, St. Hedwig of Silesia was buried in Poland in 1243. When her body was exhumed in the 17th century, it was discovered that her brain was preserved, and at the time it was thought to be due to divine powers.

Morton-Hayward's working hypothesis is that under certain circumstances, substances such as iron can catalyze the formation of cross-links between proteins and lipids, forming more stable molecules that resist degradation. The nature or ratio of proteins and lipids in the brain may be key.

“The mechanisms are similar to those seen in neurodegenerative diseases such as dementia,” she says. “So if we can understand what happens to the brain after death, we may be able to understand what happens to the brain as it ages during life.”

“It's great news that the data is being made public,” he says. brittany moeller He is one of the researchers at James Cook University in Melbourne, Australia who discovered that: Brain preservation is more common than thought. “This may raise researchers' awareness of the possibility of preserving brain material,” she says.

This is important because preserved brains are often the same color as the surrounding soil. “Therefore, it is very likely that brain material is not recognized for what it is and is frequently discarded during archaeological excavations,” Moller says.

Although this study focused on the human brain, the findings should also apply to animals. Morton Hayward says there are at least 700 examples of animal brains preserved as fossils, the oldest of which he says is an arthropod from 500 million years ago.