Strontium isotope results may be deeply flawed

Thanks to Jon for alerting me to this new research. Quote:

Reference maps showing strontium isotope data dominated by the isotopic signature of modern agricultural lime, do not show the true strontium isotopic composition of the area during prehistoric times, when the individual being studied lived, or the object being studied was in, created.  This can result in erroneous interpretations of the origin and movement of these prehistoric people and artefacts.
As readers of this blog may have noticed, I have been very circumspect about the results of work using strontium isotope measurements which purports to show the "origins" of either people or domesticated animals found in archaeological contexts.  Just put "strontium" into the search box, and assorted entries will pop up.  Here are some:

https://brian-mountainman.blogspot.com/2018/08/strontium-levels-in-cremated-bone-what.html

https://brian-mountainman.blogspot.com/2013/03/more-on-durrington-walls-cattle.html

https://brian-mountainman.blogspot.com/2018/08/now-smithsonian-goes-completely-bonkers.html

https://brian-mountainman.blogspot.com/2013/03/strontium-isotope-ratios.html

https://brian-mountainman.blogspot.com/2018/08/the-mythologising-of-west-wales-role-of.html

https://brian-mountainman.blogspot.com/2018/09/does-current-archaeology-actually-read.html

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First, the report from Denmark:

Agricultural lime disturbs natural strontium isotope variations: Implications for provenance and migration studies http://advances.sciencemag.org/content/5/3/eaav8083 on Neolithic feasts and far-travelled pigs

https://phys.org/news/2019-03-strontium-isotope-disturbed-agricultural-lime.html

DOI: 10.1126/sciadv.aav8083

Strontium isotope maps are disturbed by agricultural lime
March 13, 2019, Aarhus University

Strontium isotopes are frequently used in archaeological studies to establish the provenance and migration history of prehistoric people and artifacts. Many of these studies may be based on incorrect data. A Danish study shows that agricultural lime can alter the composition of strontium isotopes dramatically, so that the modern isotopic signature of an area may be very different from the prehistoric signature.

A study by researchers at Department of Geoscience, Aarhus University, Denmark now shows that strontium isotopes may often be used incorrectly in archaeological studies, as the widespread use of added (strontium-rich) agricultural lime in low- to non-calcareous soils can dramatically alter the strontium isotopic composition of the surface waters running through them and the plants growing within them.
This is of special significance for strontium-isotope based provenance studies, where the strontium isotopic values measured in a prehistoric person's remains or in a given artefact are compared to measured strontium isotopic values in the surrounding, modern environment. Reference maps showing strontium isotope data dominated by the isotopic signature of modern agricultural lime, do not show the true strontium isotopic composition of the area during prehistoric times, when the individual being studied lived., or the object being studied was in created.
This can result in erroneous interpretations of the origin and movement of these prehistoric people and artefacts.
In their study published in Science Advances, the geologists Erik Thomsen and Rasmus Andreasen from Aarhus University discuss two prominent examples of this:
The iconic Bronze Age women, the Egtved Girl and the Skrydstrup Woman, who were found in Denmark in 1921 and 1935 respectively, but were recently (2015 & 2017) interpreted to have originated far away from Denmark. Moreover, the Egtved Girl was interpreted by the study's authors to have traveled back and forth between Denmark and another place, likely her homeland that was believed to be southern Germany.

These conclusions became a part of a larger framework of ideas of extended European mobility, migration, and trade, during the Bronze Age.
Conversely, the strontium data presented in the new study show that these two women could have obtained their strontium isotopic signatures within 10 km of their burial mounds, and do not indicate any cause to suspect that the women came from afar or traveled great distances during their lifetimes.

It is noteworthy that the effects of agricultural lime on the strontium isotopic composition demonstrated here is not isolated to this study's field areas in western Denmark but is likely to occur worldwide in arable areas with non-calcareous soils. The use of agricultural lime is ubiquitous in farming on less fertile soils to provide calcium for the plants and adjust soil acidity. Thus, many studies using strontium isotopes for provenance and mobility studies in these farmed low-calcareous areas may well need revision, and researchers should use care when sampling in these areas for such studies, in the future.

Explore further: The Bronze Age Egtved Girl was not from Denmark
More information: E. Thomsen el al., "Agricultural lime disturbs natural strontium isotope variations: Implications for provenance and migration studies," Science Advances (2019).

http://advances.sciencemag.org/content/5/3/eaav8083

Read more at: https://phys.org/news/2019-03-strontium-isotope-disturbed-agricultural-lime.html#jCp

Comment:

As far s I can see, this research is very sound.  And it has major implications for the UK -- especially for the Palaeozoic parts of Britain where soil acidity is high and where "liming" of the land has been going on continuously for 500 years as a means of increasing agricultural productivity.  What the researchers found was that the strontium signature in water and in plants went down quite substantially with increasing lime use in farmed areas.  That means that samples taken from such areas (and used in the creation of strontium isotope base maps) give signatures substantially lower than they should be -- and lower than they were when Neolithic / Bronze age human and farm animals were alive.  The amount of error will depend on exactly how and where the "base point" sampling was done.

So if we assume (as we must now do) that the UK maps used in "migrant provenancing research" use background figures that are too low (for example, 0.7097 against a true figure of 0.7124; or 0.7099 as against a true figure of 0.7131), they will need to be substantially corrected upwards and redrawn.  While this does not invalidate the principle that the Palaeozoic geological provinces of Britain have higher strontium signatures (mostly over 0.7100) than the SE of England, and that the chalklands may have signatures as low as 0.7075, there must be multiple inaccuracies. In this context, there is no way that the claim of Snoeck et al that they have done "accurate provenancing" of certain Stonehenge cremated bones to one little piece of West Wales can be sustained.  The claim was dodgy enough as it was -- now it surely has to be binned.

http://www.ox.ac.uk/news/2018-08-02-new-light-shed-people-who-built-stonehenge

https://www.nature.com/articles/s41598-018-28969-8#

There is a sense of deja vu in all of this.  When new scientific techniques are adopted and found to be novel and useful, there is often a rush of publications announcing wondrous new discoveries.  Then a little later anomalies and errors become apparent, and correction factors begin to be introduced -- since all techniques have their limitations.  This has happened with radiocarbon dating -- and as I have said often on this blog, Quaternary chronology is still screwed up in the UK because of the chaos associated with the over-application of amino acid dating in the period 1980 - 2000.