Scientists May Have Solved Mystery of Why Some Brains Survive for Millennia
Researchers say wet, low-oxygen conditions can turn brain decay into a preservation process, explaining why some brains last thousands of years.
According to a report from Smithsonian Magazine, shared via Slashdot, archaeologists have discovered more than 4,400 preserved human brains worldwide, some as old as 12,000 years. In hundreds of cases, the brain was the only soft tissue left among otherwise skeletal remains. Normally the brain is one of the first organs to decompose after death, so these finds have puzzled researchers.
A team of scientists, including paleobiologist Alexandra Seviour from the University of Oxford, describes a possible answer in a study published in the August 7 issue of the Journal of Proteome Research. After experiments on 72 mouse carcasses, the researchers suggest that if a brain ends up in a wet, oxygen-starved environment, the processes that usually cause decay can have the opposite effect.
In oxygen-rich conditions, free radicals trigger a chemical chain reaction that breaks down brain proteins rapidly. But in low-oxygen environments, the researchers found, free radicals instead react and bond with nearby proteins, making the tissue tougher and more resistant to decomposition.
"Under the right conditions, preservation actually arises from decay itself: The same reactions that degrade tissue can also weld the breakdown products together into something far tougher," Seviour told Live Science. The findings show that "decay is not the opposite of preservation but, under specific chemical constraints, one of its mechanisms," the researchers wrote in the paper.
The study offers a potential explanation for why brains can persist for millennia while all other soft tissue disappears, though further research may be needed to confirm the exact chemical processes.