Accelerated bone deterioration in last 70 years at famous Mesolithic
peat bog in peril
Results suggest similar decline may be happening across equivalent sites


Date:
July 29, 2020
Source:
PLOS
Summary:
Alarming results from a 2019 survey of well-known archaeological
site Agero"d reveal drastic bone and organic matter deterioration
since the site's initial excavations in the 1940s, suggesting
action is needed to preserve findings from Agero"d and similar
sites, according to a new study.



FULL STORY ========================================================================== Alarming results from a 2019 survey of well-known archaeological site
Agero"d reveal drastic bone and organic matter deterioration since the
site's initial excavations in the 1940s, suggesting action is needed to preserve findings from Agero"d and similar sites, according to a study published July 29, 2020 in the open-access journal PLOS ONE by Adam
Boethius from Lund University, Sweden, and colleagues.


========================================================================== Archaeologists need organic remains like bone and plant matter to
reconstruct ancient human cultures and environments; however, organic
matter is only preserved under specific conditions, becoming rarer
as sites deteriorate due to environmental change like drainage and
pollution. Boethius and colleagues here attempt to measure and analyze
this phenomenon using the well-known Swedish Mesolithic peat bog site
Agero"d I (8700-8200 cal BP), uncovered in the 1930s with excavations
in the 1940s and 1970s, and renowned for its abundant and well-preserved quantities of bone and flint.

In 2019, the authors and colleagues excavated five test pits (five square meters total) at Agero"d, near areas containing the greatest number of
remains as found in previous excavations. They then compared 61 bone,
tooth, and antler fragments (as determined to the species or family level) uncovered in the test pits with 3716 bone fragments previously retrieved
during the 1940s and 1970s excavations.

Osteological analyses of the bone remains from 2019 as compared with
those found in the 1940s and 1970s indicate that bones at Agero"d have
suffered accelerated deterioration over the last 75 years, with measured
bone weathering averages going from 2.8 in the 40s (hard, heavy bones with occasional cracks) to 3.4 in the 70s (lighter bones with bigger cracks
and interior exposure) to 3.7 in 2019 (light and heavily eroded bones,
outer surface loss). More worryingly, complete destruction of some bones
was suggested in this latest excavation, which uncovered no smaller
fur game bones or bird bones, in contrast to earlier excavations --
likely because small mammals and birds have smaller, lighter bones that
break down faster than heavier bones. The authors also detected oxidized
pyrite in the bones from 2019, in contrast to those from the 40s and 70s
(which showed only non-oxidized pyrite). This suggests that oxygen was re-introduced into the bog environment between the 1970s excavations and
2019, destabilizing the typically anoxic bog conditions and permitting
pyrite to oxidize and produce sulphuric acid (which drops soil pH and
damages organic matter) as a by-product.

Although the 2019 excavation was much smaller in scope than previous excavations -- in part to help limit further potential destruction at the
site -- the careful location of the test pits suggests the decay and loss
of bone remains documented here is likely indicative of issues occurring
across Agero"d. The authors note that Agero"d has not been subjected
to more or heavier encroachment than most other archaeological sites,
raising concerns as to the state of preservation in similar sites. They
note that though Agero"d still holds significance, it has already lost
many of its unique preservation properties -- and if future steps to
protect the site are not taken, then the organic remains preserved in
its peat bog for 9000 years will soon be lost forever.

The authors add: "The fact is that we know very little of the state of
our buried archaeological remains from most areas, but we are increasingly becoming aware of their rapid destruction. Unfortunately, this destruction
is not only a matter of connecting the present with long lost ancient
cultures or societies, as an interest of the ancient past. The record
being destroyed is also a long- term perspective database which,
if properly used, can help us create models of future environmental
scenarios. Especially if going back to periods after the last Ice Age
when the climate experienced rapid changes in global warming while
human groups started to affect their local environment at much higher
levels than previously seen. Unfortunately, the older the remains, the
rarer and more vulnerable they become and if the pattern observed at
Agero"d is similar in other areas we are in an extreme hurry to remedy
the situation and recreate soils that allow organic preservation or,
indeed, excavate the remains. If we do nothing, wait and hope for the
best it is likely that the archaeo-organic remains in many areas will
be gone in a decade or two. Once it is gone there is no going back and
what is lost will be lost forever. It is worth considering, especially
given recent advances in archaeological molecular science, i.e. aDNA and
stable isotopes etc. If the organic remains deteriorate, these type of
analyses will not be possible to do anymore and given the information
we are now generating from them it will be a devastating blow to our understanding of ancient cultures, diet and subsistence strategies,
migration and mobility etc."

========================================================================== Story Source: Materials provided by PLOS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Adam Boethius, Mathilda Kja"llquist, Ola Magnell, Jan Apel. Human
encroachment, climate change and the loss of our archaeological
organic cultural heritage: Accelerated bone deterioration
at Agero"d, a revisited Scandinavian Mesolithic key-site
in despair. PLOS ONE, 2020; 15 (7): e0236105 DOI:
10.1371/journal.pone.0236105 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200729141417.htm

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