Human Brains Have Been Mysteriously Preserved For Thousands Of Years

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Intact human brains 12,000 years old or more have been found in unexpected places such as shipwrecks and waterlogged graves, but it is unclear what preserved them.

A study of human brains that have been naturally preserved for hundreds or thousands of years has identified 1300 cases where the organs have survived even when all other soft tissues have decomposed. Some of these brains are more than 12,000 years old.

“Brains of this type, where they’re the only soft tissue preserved, have been found in sunken shipwrecks and in waterlogged graves where the bones are just floating,” says Alexandra Morton-Hayward at the University of Oxford. “It’s really, really strange.”

Alexandra Morton-Hayward holding a 1000-year-old preserved brain Graham Poulter

Morton-Hayward…and her colleagues have done the first ever systematic study of the phenomenon. They have put together a database of more than 4400 preserved human brains found all over the world.

In most cases, the brain preservation could be explained by known processes. For instance, the brains of Incan human sacrifices entombed on top of a volcano in South America around AD 1450 were freeze-dried along with the bodies. But the known processes preserve all soft tissues, not just brains. They don’t explain the 1300 cases where brains are the only soft tissue to survive.

Morton-Hayward’s working hypothesis is that, in certain circumstances, substances such as iron can catalyse the formation of cross-links between proteins and lipids, forming more stable molecules that resist degradation. The nature of the proteins and lipids found in brains, or their ratio, might be the key.

https://www.newscientist.com/articl...ysteriously-preserved-for-thousands-of-years/

maximus otter

 

[maximus otter]

Intact human brains 12,000 years old or more have been found in unexpected places such as shipwrecks and waterlogged graves, but it is unclear what preserved them.

A study of human brains that have been naturally preserved for hundreds or thousands of years has identified 1300 cases where the organs have survived even when all other soft tissues have decomposed. Some of these brains are more than 12,000 years old.

“Brains of this type, where they’re the only soft tissue preserved, have been found in sunken shipwrecks and in waterlogged graves where the bones are just floating,” says Alexandra Morton-Hayward at the University of Oxford. “It’s really, really strange.”

Alexandra Morton-Hayward holding a 1000-year-old preserved brain Graham Poulter

Morton-Hayward…and her colleagues have done the first ever systematic study of the phenomenon. They have put together a database of more than 4400 preserved human brains found all over the world.

In most cases, the brain preservation could be explained by known processes. For instance, the brains of Incan human sacrifices entombed on top of a volcano in South America around AD 1450 were freeze-dried along with the bodies. But the known processes preserve all soft tissues, not just brains. They don’t explain the 1300 cases where brains are the only soft tissue to survive.

Morton-Hayward’s working hypothesis is that, in certain circumstances, substances such as iron can catalyse the formation of cross-links between proteins and lipids, forming more stable molecules that resist degradation. The nature of the proteins and lipids found in brains, or their ratio, might be the key.

https://www.newscientist.com/articl...ysteriously-preserved-for-thousands-of-years/

maximus otter

Why Some Human Brains Don’t Rot for Thousands of Years

No part of our body is as perishable as the brain. Within minutes of losing its supply of blood and oxygen, our delicate neurological machinery begins to suffer irreversible damage. The brain is our most energy-greedy organ, and in the hours after death, its enzymes typically devour it from within. As cellular membranes rupture, the brain liquifies. Within days, microbes may consume the remnants in the stinky process of putrefaction. In a few years, the skull becomes just an empty cavity.

In some cases, however, brains outlast all other soft tissues and remain intact for hundreds or thousands of years. Archaeologists have been mystified to discover naturally preserved brains in ancient graveyards, tombs, mass graves and even shipwrecks. Scientists at the University of Oxford published a study earlier this year that revealed that such brains are more common than previously recognized. By surveying centuries of scientific literature, researchers counted more than 4,400 cases of preserved brains that were up to 12,000 years old.

Such unusual preservation involves the “misfolding” of proteins—the cellular building blocks—and bears intriguing similarities to the pathologies that cause some neurodegenerative conditions.

The misfolding and clumping of brain proteins is the underlying cause of dozens of neurodegenerative disorders, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis (ALS) and the cattle illness bovine spongiform encephalopathy (BSE), also called mad cow disease. Now scientists are discovering that some misfolded proteins also can form clumps after death—and persist for hundreds or thousands of years.

A classic example is egg white. Normally, it is a transparent liquid, but when conditions change—as when an egg is fried or boiled—its proteins unravel, become entangled and form clumps. “That’s an aggregate,” says Ulrich Hartl, a leading researcher of protein-folding diseases at the Max Planck Institute of Biochemistry in Martinsried, Germany. “The same thing happens in your brain at a microscopic level.” Many diseases share a similar underlying mechanism: the protein abandons its healthy native state, unfurls and becomes entangled in a jumbled mass with other misfolded proteins.

In diseases, the misfolded version becomes the protein’s most thermodynamically stable state, often making the aggregations irreversible. Hartl says he would not be surprised if a similar mechanism lay behind ancient brain preservation.

https://www.scientificamerican.com/article/why-these-millennia-old-brains-are-so-well-preserved/

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