- Brains preserve better than previously thought, study finds
- Over 4,000 skulls analyzed, debunking decay assumptions
- Preservation methods vary; one-third remain unexplained
Long believed by experts to be among the first organs to decompose and decay after death, recent research indicates this is not the case.
Indeed, a group of scientists from Oxford University have determined that brains preserve pretty well; however, they are still determining how nearly one-third of the brains have endured for as long as they have.
Anciently, whenever archaeologists discovered a well-preserved brain that was quite old, it was considered an anomaly, or at the very least, the result of deliberate preservation efforts by the ancients.
To determine the truth about brain decay, researchers conducted a new study combed through an archaeological archive containing over 4,000 human skulls, many dating back 12,000 years or more.
They concluded that the brain’s tissues are considerably more resistant to degeneration than scientists believed.
Furthermore, organizing the brains according to location revealed that preservation can be improved by considering local environmental conditions.
In general, soft tissues such as internal organs and musculature are much less frequently discovered by archaeologists than hard tissues such as bones and skin.
This led them to conclude that skin can be preserved similarly to leather, whereas bones are rigid.
Decomposition is typically impeded or halted through procedures such as mummification, embalming, or chilling.
Such is the case with human remains preserved in peat bogs or those entombed in arid, mineral-rich soil; such occurrences are infrequent.
However, it was long believed that the brain was among the first substances to decompose following mortality.
To disprove this claim, the research team conducting the new study combed through the scientific literature in quest of references to preserved human nervous system tissues.
With documentation in hand, they examined the chemical and physical characteristics of the remains under investigation and assessed the location of their discovery.
This included their location on a map and chemical evidence surrounding their brain preservation and the climatic conditions at the time of death.
The research comprised a compilation of 4,405 brain samples obtained from various locations across the globe, mainly from Europe and none from Antarctica.
Five discrete methods of preservation were identified among the samples: saponification, chilling, tanning, dehydration, and an enigmatic category identified as ‘unknown.’
Unidentified processes have preserved approximately one-third of the brains that have been documented.
This category includes specimens discovered in tombs, sunken ships, and wooden and lead containers.
When archaeologists discover these ancient human remains, the brain is frequently the only soft tissue present.
The transformation of fat and hydroxide into soap via saponification is analogous to the resultant brain consistency, which can range from rigid and crumbly to malleable and paste-like.
This type of preservation occurred when the chemical bonds of lipids in the brain were severed, combining their constituent elements with metals such as calcium, sodium, or magnesium to form adipocere, also referred to as “grave wax.”
The majority of saponified minds are younger than two centuries.
Freezing is self-explanatory and typically occurs when an individual perishes in extremely frigid climates.
Because cells can degrade after repeated thawing and refreezing (think of spinach that has been frozen and thawed), brains preserved by freezing are frequently challenging to study.
The “slightly pliable, dark-colored mass” tanning produces resembles another well-known tanning byproduct: leather.
The brains of bodies preserved in peat were most frequently subjected to tanning, as the environmental conditions inhibited bacterial degradation of the tissues.
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The predominant preservation method, dehydration, constituted 1,667 samples, or 38%.
As a result of water loss, these brains became highly brittle.
These brains either resulted from natural processes (e.g., exposure to air currents or hot, arid climates) or deliberate mummification.
The chemical composition and consistency of the ‘unknown’ brains were notably comparable.
This group comprised 1,308 brains or nearly one-third.
They constituted the sole soft tissue remnants alongside skeletons in these samples; some were as old as 12,000 years.
Scientists are still determining how this preservation method, which appears to be exclusive to the brain and not other body tissues, operates.
Instead of being discovered in a particular environment, these brains were frequently found in the remains of individuals interred in mass graves.
