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Preserved Human Brains From 12,000 Years Ago Among Thousands in New Archive


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Researchers have created an unprecedented archive of thousands of human brains preserved in the archaeological record, some of which date back several millennia.

A team led by Alexandra Morton-Hayward, a forensic anthropologist and doctoral candidate at the University of Oxford's Department of Earth Sciences in the United Kingdom, reviewed the scientific literature and canvassed archaeologists around the world for a research project. These investigations resulted in a global archive collating records—and some specimens—of more than 4,400 preserved human brains.

These brains originate from 213 unique sources across every continent apart from Antarctica. The oldest brains included in the work, which has been published in the journal Proceedings of the Royal Society B, are dated to around 12,000 years ago. The youngest are from the 20th century. The preserved brains collated in the archive are documented in records stretching as far back as the 17th century.

The database, which draws on source material in more than 10 languages, represents the largest, most complete study of the archaeological literature on this issue to date, exceeding the number of brains compiled in previous attempts 20-fold.

A 1,000-year-old preserved human brain from Belgium
The thousand-year-old brain of an individual excavated from the c. 10th century churchyard of Sint-Maartenskerk in Ypres, Belgium. This specimen is among more than 4,000 recorded in a newly compiled archive. Alexandra L. Morton-Hayward

The preservation of human soft tissue in the archaeological record is considered to be relatively rare and the survival of entire organs is particularly unusual, except in cases where deliberate intervention, such as embalming or freezing, halts the process of decay.

The brain is usually among the first organs to decompose after death. Thus the perception remains that naturally preserved brains represent "unique" or "extremely rare" discoveries, especially in the absence of any other soft tissues.

But the latest research challenges these perceptions, highlighting that preserved brains occur in much greater abundance than traditionally thought, persisting thanks to conditions that prevent decay.

The preserved brains in the archive were found in various environments around the world, ranging from arid deserts and frozen mountain passes to low-lying wetlands.

The researchers identified several mechanisms that led to preservation, including dehydration, freezing, saponification (a process characterized by the transformation of fats into a substance known as "grave wax") and tanning (a process that often occurs in peat bogs, which are characterized by highly acidic water, low temperatures and a lack of oxygen).

More than 1,300 of the brains in the archive were found to have been preserved in the absence of other soft tissues. This find prompted questions about why the brain persisted in these cases when the other organs did not. Intriguingly, some of these brains also represent the oldest in the archive, with several dating to the last Ice Age.

This suggests that nervous tissues persist in an abundance that has been overlooked in the archaeological literature, with the researchers proposing that an unknown mechanism—yet to be explained—may be responsible for their preservation.

"I think what's really intriguing about this research is that although we know the brain can liquefy really quickly, clearly, in some circumstances, it also preserves and on incredibly long timescales," Morton-Hayward told Newsweek. "So, I would argue that we need to start thinking in greater depth about soft tissue preservation."

The brains in the archive are universally described as discolored and shrunken to varying degrees. They belonged to all manner of individuals, including Egyptian royalty, British monks, Arctic explorers and victims of war.

The archive includes brains from a "bewildering array" of archaeological sites. Examples include a brain preserved in a severed skull that was mounted on a wooden spike at the edge of a lake in Stone Age Sweden and numerous specimens from a prehistoric cemetery in Upper Egypt found in shallow, sandy graves.

The database also includes the brain of an Iron Age man, preserved in a Danish peat bog, as well as those of children killed in an Inca ritual sacrifice during the 15th century, who were buried in a pit tomb at the summit of the dormant volcano Mount Llullaillaco in the Andes (the world's highest archaeological site). More modern examples include a number of brains from a Spanish Civil War (1936-1939) mass grave that were preserved even in skulls highly fragmented by gunshot trauma.

A researcher holds a preserved brain
Researcher Alexandra Morton-Hayward shows the remains of a 200 year-old brain preserved in formalin. The brain is usually among the first organs to decompose after death but in certain circumstances it can be preserved for... Graham Poulter

Preserved soft tissues are a valuable find for archaeologists because they generally provide a greater depth and range of biological information than hard tissues alone. Yet less than 1 percent of preserved brains have been investigated for ancient biomolecules—numerous substances produced by living organisms, such as carbohydrates, proteins and lipids.

Thus, the latest work represents an "untapped archive" that could shed light on human evolution, as well as help us to better understand ancient health and disease. The research could even provide insights into neurodegenerative conditions that affect people today, such as Alzheimer's and other forms of dementia.

"The problem that we have with brains is where they are excavated, they're constantly described as this unique or exceptionally rare phenomenon," Morton-Hayward said. "When you describe something that way, you limit the access researchers have to investigate the material because it's precious and one-of-a-kind. Obviously, we can't lose sight of the fact that these are human remains and they should be treated with dignity. But we're also losing a lot scientifically by not studying them.

"So, I really hope that this paper will raise awareness for excavating archaeologists: keep your eyes open, you never know what you'll find and let's see what we can learn from this material."

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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.

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