In 2008, researchers dug out a black human skull covered with thick mud in a ponding pit in heslington village north of London. Although more than 2600 years have passed, the brain tissue in the skull is still intact.
Analysis shows that this brain belongs to a middle-aged man who lived between the 7th and 5th centuries BC. Researchers have previously found well preserved brains and brain tissues, including those deliberately preserved by mummification. But the brain found in heslington is very different because it is the only human brain left at this particular time.
The researchers examined the brain at the molecular level, hoping to find the answer from folds and grooves. Through a series of experiments, the researchers identified more than 800 proteins and proved that they even retained some of their ability to produce immune response.
After human death, the body will eventually decompose. The brain is particularly easy to break down because of their high fat content. Molecules such as DNA are easy to be destroyed and will decompose relatively quickly, but proteins are slightly resistant to decomposition.
Proteins play a key role in the preservation of heslington's brain. They fold themselves into stable 'aggregates' to prevent protein degradation, but can this fully explain why the brain is well preserved?
There may be other factors: the brain was not deliberately preserved because there were no signs of corrosion or similar.
The researchers also examined brain samples for any signs of neurological disease, but the analysis showed no evidence of protein accumulation.
The researchers believe that the latest findings on protein stability will be conducive to biomarker research, proteomics and archaeology.