Peat bogs across Northern Europe have long fascinated archaeologists due to their remarkable ability to preserve human remains for thousands of years. This preservation is not merely a product of waterlogging, but rather a direct consequence of the chemical environment created by sphagnum moss. As sphagnum moss dies and decays, it releases a complex carbohydrate polymer known as sphagnan into the surrounding water. Sphagnan reacts chemically with the calcium and metals in the bog, which effectively strips the water of these essential nutrients. Deprived of calcium, local microorganisms and bacteria cannot build or maintain their cell walls, which halts their metabolic processes. Consequently, the lack of microbial activity prevents the decay of organic material, keeping the soft tissues of bog bodies largely intact. Furthermore, sphagnan binds to proteins and enzymes, tanning the skin in a process similar to leather production. At the same time, the highly acidic nature of the bog dissolves calcium phosphate in bones. This explains why many bog bodies are recovered with beautifully preserved skin and hair, yet their skeletal structures are often severely depleted or entirely absent.
According to the passage, what is the direct cause of the halting of metabolic processes in local microorganisms?
- AThe binding of proteins and enzymes to the outer skin layer of the human remains
- BThe lack of microbial activity, which prevents decaying moss from releasing sphagnan into the water
- The depletion of calcium in the bog water, which prevents bacteria from maintaining cell wallsAnswer
- DThe accumulation of dissolved calcium phosphate, which poisons the bacterial population