Giles agrees. “You’re dealing with entities that affect your life, gods or spirits, there’s something supernatural there that can be accessed through the swamp,” he says. There may have been an element of circularity in offering people to the gods through the swamp, Giles adds. “Because people were taking so much from the swamps, it seems they were forced to give things back. Sometimes it’s cauldrons, sometimes it’s human remains,” he says. Sometimes they were food offerings like butter. “If you give up a person, a life – that could be the best kind of gift you can give.” But while there is evidence that Lindow Man, Tollund Man and Grauballe Man and others were human sacrifices, we should not assume that all the bodies were, warns Giles. For some bodies, like the Lindow Woman, there simply isn’t enough left to create a convincing picture of how they died. “There are some bodies that show no signs of violence and these people may have just drowned,” he points out. “These are dangerous landscapes. People die in the swamp – they die of exposure, they die trying to cross it, they lose their footing or they misjudge where they’re walking. Some of them would be accidental deaths.” Others, he says, may have been simple murders. Perhaps a deserted swamp was sometimes just a convenient place for nefarious deeds. There may also have been suicide victims among the dead, perhaps placed there at a time when such deaths were met with fear rather than empathy.
“Marshes may have been considered the right places to place a dangerous body – someone who died mysteriously or unnaturally,” says Giles. “Some of it had to do with the Church saying it doesn’t want these people in its cemeteries. Some of it is that the swamp is a powerful place beyond human access where the dead can be confined.” — Full disclosure: Researching bog bodies for this story led to more than one surprise for the author, including the discovery that one of the world’s leading experts on them is a relation. For the sake of transparency, Miranda Aldhouse-Green is the author’s first cousin once removed. — Martha Henriques is a BBC Future Planet editor and tweets at @Martha_Rosamund — Join a million future fans by liking us on Facebook or following us on Twitter or Instagram. If you enjoyed this story, subscribe to bbc.com’s weekly feature newsletter, called ‘The Essential List’ – a curated selection of stories from BBC Future, Culture, Worklife, Travel and Reel delivered to your inbox every Friday .