Bog body  A bog body is a human cadaver that has been naturally mummified in a peat bog. Such bodies, sometimes known as bog people, are both geographically and chronologically widespread, having been dated to between 8000 BCE and the Second World War. The unifying factor of the bog bodies is that they have been found in peat and are partially preserved; however, the actual levels of preservation vary widely from perfectly preserved to mere skeletons. Unlike most ancient human remains, bog bodies often retain their skin and internal organs due to the unusual conditions of the surrounding area. Combined together, highly acidic water, low temperature, and a lack of oxygen preserve but severely tan their skin. While the skin is well-preserved, the bones are generally not, due to the dissolution of the calcium phosphate of bone by the peat's acidity. The oldest known bog body is the skeleton of Koelbjerg Man from Denmark, who has been dated to 8000 BCE, during the Mesolithic period. The oldest fleshed bog body is that of Cashel Man, who dates to 2000 BCE during the Bronze Age. The overwhelming majority of bog bodies – including examples such as Tollund Man, Grauballe Man and Lindow Man – date to the Iron Age and have been found in northwest European lands, particularly Denmark, Germany, the Netherlands, the UK and Ireland. Such Iron Age bog bodies typically illustrate a number of similarities, such as violent deaths and a lack of clothing, which has led archaeologists to believe that they were killed and deposited in the bogs as a part of a widespread cultural tradition of human sacrifice or the execution of criminals. Bogs could have indeed been seen as liminal places positively connected to another world, which might welcome contaminating items otherwise dangerous to the living. More recent theories postulate that bog people were perceived as social outcasts or "witches", as legal hostages killed in anger over broken treaty arrangements, or as victims of an unusual death eventually buried in bogs according to traditional customs. The German scientist Alfred Dieck published a catalog of more than 1,850 bog bodies that he had counted between 1939 and 1986 but most were unverified by documents or archaeological finds; and a 2002 analysis of Dieck's work by German archaeologists concluded that much of his work was unreliable. The newest bog bodies are those of soldiers killed in the Russian wetlands during the Second World War. The preservation of bog bodies in peat bogs is a natural phenomenon, and not the result of human mummification processes.