Why Are Peat Bogs So Good at Preserving Human Remains?

Human bodies buried in bogs can retain some features -- like perfectly preserved skin, right down to forehead wrinkles -- for thousands of years. Learn how this natural mummification process works in today's episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from how Stuff Works, Hey, brain Stuff,
Lauren voke obam here. Bogs are pretty awesome as far
as sweeping mud fields of dead buried plants go. They
store the energy of generations of plants in their mass,
which can be harvested as pete. They're also havens for mummies.
Artifacts buried beneath bogs, including human bodies, may be kept

(00:24):
in astonishingly good condition for thousands and thousands of years.
They've all got stories to tell, and today we'll look
at the weird science that makes their preservation possible. Common
in cool, wet parts of the world, bogs are water
logged grounds that form when decaying plant matter, known as pete,
accumulates in low lying areas. Bogs are usually found in

(00:46):
cool climates and often in lake basins created by ice
age glaciers that no longer get a steady flow of
river or stream water over time. Mosses cover the heap
like a blanket, and in most cases, this mossy layer
is primarily made of am called sphagnum. Sphactum. Moss has
the power to transform an entire landscape. Water or dirt

(01:06):
trapped beneath sheets of it. Will be cut off from
the normal supply of oxygen from the atmosphere. Also, sphagnum
soaks up calcium and magnesium, which makes the underlying soil
and water mildly acidic. Since bacteria and fungi find those
conditions inhospitable, the dead vegetation decomposes at a phenomenally slow rate.
Instead of breaking down right away, it lingers piling up.

(01:28):
Over time, masses of the botanical waste gradually turn into pete,
a soggy, mud colored substance. Pete can be used as
animal bedding and as a fossil fuel, which makes it
an important commodity in places like the Irish Midlands and
in Scotland, where it's the traditional fuel for fires that
dry out grain to make Scotch whiskey, imparting smoke and
its flavors along with that heat. But two archaeologists, pete

(01:51):
is a lot less valuable than the human corpses that
sometimes come with it. Bogs have long fascinated humans, not
just for their fossil fuels. The spongee oil has intrigued
people as far back as the Bronze Age. Many people
died in these bogs or were placed there after their deaths,
and these bog bodies, as they're known, have been found
all over the world. The wetlands of northwestern Europe, for instance,

(02:13):
is a bog body hub. Hundreds of these corpses have
turned up in Germany, England, the Netherlands and neighboring countries.
In eleven pete harvesters working in Ireland accidentally ran over
a Bronze age corpse with a milling machine. Dubbed the
Castle Man. The harvester found all that was left of
an adult male who probably died in his twenties. His
body was riddled with injuries, including a broken arm and

(02:36):
a nasty cut across the backside. Some of these may
have been caused by the compressing weight of the bog
moss above him or the blades of that milling device. Nevertheless,
archaeologists have reason to suspect that the casual Man was
a ritualized sacrifice victim. Other European bog bodies have displayed
stab wounds, slit throats, and evidence of torture. Historians think

(02:56):
that the local wetlands were once a hotbed for religious sacrifices.
Carbon dating tells us the casual man perished about four
thousand years ago, seven centuries before King Tuton Common was born.
To date, he's the oldest European bog body on record
with intact skin. That's right, the corpse of somebody who's
been dead for four millennia still has its skin attached,

(03:17):
and this isn't a fluke. Lots of bog bodies retain
some or all of their original skin. The Taaland Man,
a twenty three hundred year old corpse recovered from a
Denmark peat bog in nineteen fifty, has skeletonized hands, but
elsewhere his skin is so well preserved that little details
like the wrinkles on his forehead are still visible. Although
the Taaland Man's skin didn't rot away, the mummification process

(03:40):
did change its appearance and texture. Like the casual man
and lots of other bog bodies, he sports leathery, dark
brown skin. Some of them also have preserved hair that
was dyed red after death. This is most likely caused
by a recently discovered polymer called sphagnum, which seeps out
of dead sphagnum moss. If you think of leather, it's
through a process called tanning that strengthens the bonds between

(04:03):
some of the natural fibers in animal hides. As a
tanning agent, sphagnan has the same effect on human skin,
rendering it tough and tea colored. Sphagnan also binds with nitrogen,
which bacteria need to survive, so by removing nitrogen from
the environment, sphagnan helps prevent the spread of microorganisms that
would normally be breaking down human and animal remains. And Furthermore, sphagnan,

(04:26):
along with the acid that it turns into, pulls calcium
right out of dead bodies. Bones get weakened in the process.
Although sphagnan does a fine job of preserving skin, it's
calcium thievery isn't great for skeletons. Mummies have been found
in certain bogs with soft, extra flimsy bones that are
about astarte's cardboard and that have been distorted by heavy peat,

(04:47):
but that's assuming the decalcification process doesn't altogether eliminate bones.
Lots of bog bodies have been found missing bones, and
some of the mummies are totally boneless. The latter are
basically human shaped bags of leatheries in wrapped around some
pickled organs. Not all bogs are so hostile to bones, though,
the water's acidity level varies from bogged bog and this

(05:08):
impacts corpse preservation. Archaeologists have discovered that in really acidic
peat bogs, the resident mummies have lots of skin and
soft tissue and weak or non existent bones, But there
are some boggy places with relatively alkaline water. Here the
environment pretty much has the opposite effect on corpses. A take,
for example, the Windover Archaeological Site, a peat bottomed pond

(05:30):
in Florida that became the final resting place for dozens
of Native Americans between seven and eight thousand years ago.
Skeletal remains from a hundred and sixty eight people have
turned up in the peat. A large deposit of crushed
up snail shells lying under the pond supplies the water
with magnesium and calcium carbonates That makes the water more alkaline,
neutralizing the spagnum to an extent. Instead of mummified skin bags,

(05:53):
the bog is rife with naked bones and skeletons a
bear as they are on the outside. The ancient bones
had a big surprise sides in store for scientists. Brain
tissue was found in more than ninety of the windover
pond skulls, making them extra fascinating fines by the way,
bonus fact of the episode. Most carnivorous plants, such as
sundews and pitcher plants grow in bog soils, which tend

(06:15):
to be nutrient poor. Eating animal prey is a strategy
that helps them obtain vital nutrients. Today's episode was written
by Mark Bancini and produced by Tyler clayg for iHeart
Media and how Stuff Works. For more on this and
lots of other topics that aren't too bogged down, visit
our home planet to stuff works dot com.