The human brain is surprisingly resistant to the ravages of time, according to a new study conducted by scientists from the University of Oxford. Contrary to previous beliefs, the study revealed that the brain resists decomposition far more than other soft tissues, even when the rest of the body has completely decayed. The researchers identified over 4,400 preserved human brains, dating back as far as 12,000 years ago, providing an unprecedented archive for studying our evolutionary history and the diseases that affect us.
In the past, forensic experts believed that the brain was one of the first organs to decompose following death. However, the team’s findings contradict this notion, highlighting certain circumstances in which the brain can survive. The researchers are currently investigating whether these circumstances are environmental or related to the brain’s unique biochemistry. By analyzing ancient biomolecules preserved in these archaeological brains, they hope to gain insights into the lives and deaths of our ancestors.
The preservation of soft tissue in archaeological remains is a rare occurrence, especially when the body has not been artificially embalmed or frozen. Experimental decay studies have consistently shown that the brain is susceptible to decomposition. Therefore, the discovery of preserved human brains in bodies where everything else has decayed was previously considered a highly rare phenomenon, almost one-of-a-kind.
In their quest to determine the true rarity of this phenomenon, the scientists conducted a global search for preserved human brains. They thoroughly examined published scientific literature and sought input from historians around the world, ultimately cataloging a total of 4,405 preserved human brains from 213 sources. These brains were found on every continent except Antarctica, with records dating back to the 17th century.
The preserved brains were discovered in various environments, including a mass grave from the Spanish Civil War, the sandy deserts of Ancient Egypt, victims of Incan ritual sacrifice, the Tollund Man found in a peat bog, and the bank of a lake in Stone Age Sweden. The researchers identified correlations between the environmental conditions in which the brains were found and the pathways to natural preservation. These conditions included dehydration, freezing, tanning, and saponification.
Remarkably, an incredibly high number of the preserved brains (1,308 out of 4,405) were the only surviving soft tissue structures in otherwise completely skeletonized remains. All of these brains were among the oldest in the collection, some dating back 12,000 years. Strikingly, the method of preservation might not be attributed solely to natural conditions, as the brains were found in various locations such as shallow graves, tombs, shipwrecks, burial mounds, and even decapitated heads.
This intriguing finding suggests the existence of a specific preservation mechanism for the central nervous system, separate from common modes of tissue preservation. The researchers propose that an interaction between brain molecules and environmental factors may play a role. Notably, certain metals like copper—abundant in the brain—might facilitate the formation of stable polymerized macromolecules through the fusion of proteins, lipids, and sugars.
As the scientists delve deeper into this fascinating phenomenon, there is immense potential for further discovery. The comprehensive archive of preserved human brains offers a significant opportunity for investigating major neurological disorders, ancient cognition and behavior, and the evolution of nervous tissues and their functions.
The implications of this research extend beyond the archaeological realm. By studying these preserved brains and understanding their unique preservation mechanisms, scientists may gain insights into the future of neuroscience and neurological diseases. This information might impact the development of new treatments and preventive measures for conditions such as Alzheimer’s, Parkinson’s, and other age-related cognitive decline.
Additionally, the study highlights the importance of considering the potential longevity of soft tissues when studying ancient human remains. It challenges the notion that the absence of soft tissue equates to a lack of valuable information. Instead, preserved brains offer a rich source of molecular and morphological data that can enhance our understanding of our ancestors’ lives and deaths.
Looking ahead, the research opens up exciting possibilities for future discoveries related to brain preservation and the study of ancient neurological conditions. It invites further interdisciplinary collaboration among archaeologists, biologists, and neuroscientists, fostering a deeper understanding of the links between our past and present.
The findings from this study emphasize the significance of preserving archaeological sites and human remains. Each new discovery has the potential to reshape our understanding of human history and biology. As technology advances and scientific techniques improve, future researchers will have even greater opportunities to unlock the secrets contained within our ancient ancestors’ brains.
Sources:
Proceedings of the Royal Society B: Biological Sciences