Normally, a human brain decays very quickly after death because it is soft and contains a lot of fat. However, archaeologists have often found ancient skulls with brains that are still intact, even when all other soft body parts have disappeared. Researchers at the University of Oxford have created a large database of over 4,400 preserved human brains from more than 200 archaeological sites around the world. These preserved brains are from different places and times, some dating back 12,000 years. They include brains of rulers, religious figures, explorers, and victims of war, found in various environments like lake settlements, salt deposits, and high mountains.
Scientists have identified five main ways these brains were preserved. Some were kept safe by freezing temperatures, but these did not last very long. Others were preserved by dryness in deserts, lasting up to 5,200 years. Peat bogs with acidic water preserved some for 2,800 years, and some fats turned into a soap-like substance. The most interesting method happens in wet, low-oxygen places. Here, the natural decay process actually helps to preserve the brain. In about 1,300 cases, this process kept the brain perfectly intact while other body parts decayed.
Researchers experimented with rodent bodies to understand this. They found that when there is a lot of oxygen, brain proteins break down quickly. But in low-oxygen conditions, the breakdown stops. This is because reactive molecules, which normally damage proteins, instead link broken protein pieces and fats together. This creates a strong, solid material that resists decay. The brain is well-suited for this because of its high amounts of protein and fat. The skull also helps protect the brain by blocking liquids and gases. Studying these ancient brains can give us new information about human history and biology.