Bog bodies have fascinated the public since they were first discovered in Denmark in the 1700s. Scientists today continue to ponder difficult questions about bog bodies - because of the way sphagnum moss preserves these remains, their DNA is non-extractible. Acid from the bogs also dissolves bones, making it hard to determine which injuries were sustained before and after mummification. Regardless, bog bodies offer researchers a fascinating look into the past.
While bog bodies were likely sacrifices to gods - or to the bog itself, which provided materials for fuel and weapons - they may have also been a result of capital punishment. Many of the bodies show traces of brutal ends, presenting scientists with plenty of hypotheses about when, how, and why these people perished. Scholars still have much to learn about the mysterious bog bodies from the Iron Age.
The unique preservation of bog bodies arises from the chemistry that makes bogs possible. Raised bogs, in particular, produce the best-preserved bodies - they form in basins where inadequate drainage delays plant decay once the ground becomes waterlogged.
As sphagnum moss builds up, oxygen is depleted, and bacteria is removed from the environment. Combined with the relatively cool temperatures of Northern Europe, the bogs are excellent for preserving the bodies laid to rest in them.
A specific chemical reaction creates bog bodies. Peat moss excretes the compound sphagnum, which reacts with decomposing bacteria from the bodies. This sphagnum stops the bacteria from breaking down organic matter, preserving the remains. Sphagnan also binds with nitrogen, which slows the growth of bacteria.
Humic acid dehydrates soft tissues, which wrinkles the skin and helps brown the bodies, giving them a leathery, hide-like texture.
Sphagnum moss excretes sphagnan, which extracts calcium from bones, making them flexible. It can also dissolve bones entirely - some bodies have been discovered entirely missing some bones and teeth thanks to the bog's acidity.
This dissolution can make it difficult for scientists to determine which injuries occurred before the person's passing and which are a result of the peat moss's crushing weight. Scientists primarily use fracture patterns to determine these timelines.
Decomposition occurs very slowly in a bog under the right conditions. Bronzing, however, begins soon after the body is laid to rest. Bogs are packed with tannins, a naturally occurring compound used to tan leather.
The tannins not only give the bog bodies their leather-like appearance, but tannins also preserve organs and other organic contents, including the contents of the digestive system. Researchers use these contents to determine where bog bodies once lived as well as in which season they passed.