Strontium levels in cremated bone: what the new paper actually shows

Part of Figure 2, showing the strontium isotope ratios for Great Britain, based upon geological and other data, and actual measurements.  Rhosyfelin is located on this map, for no scientific reason whatsoever.  Thousands of other locations in western and northern Britain could equally well have been recorded as possible home areas for 5 cremated individuals........

This is the new Nature paper, published today:
Strontium isotope analysis on cremated human remains from Stonehenge support links with west Wales.
Christophe Snoeck, John Pouncett, Philippe Claeys, Steven Goderis, Nadine Mattielli, Mike Parker Pearson, Christie Willis, Antoine Zazzo, Julia A. Lee-Thorp & Rick J. Schulting .
NATURE Scientific Reports, volume 8, Article number: 10790 (2018)
Published 2 August 2018
https://www.nature.com/articles/s41598-018-28969-8#

I suspect that without the involvement of Prof MPP, this would have been a much more circumspect paper, and -- dare I say it -- a much more scientific one.  However, it is what it is, and the principle of corporate responsibility applies.  We have already seen how archaeology can corrupt innocent geologists -- and now we see the same sort of corruption happening in the field of geochemistry as well.   I wonder if those involved realise what is happening to them?  Maybe they do, but maybe the lure of media fame and research IMPACT outweighs all other considerations these days.........

So let's just ignore the media hype for the moment and look at what the evidence in this paper actually shows.

Abstract

Cremated human remains from Stonehenge provide direct evidence on the life of those few select individuals buried at this iconic Neolithic monument. The practice of cremation has, however, precluded the application of strontium isotope analysis of tooth enamel as the standard chemical approach to study their origin. New developments in strontium isotopic analysis of cremated bone reveal that at least 10 of the 25 cremated individuals analysed did not spend their lives on the Wessex chalk on which the monument is found. Combined with the archaeological evidence, we suggest that their most plausible origin lies in west Wales, the source of the bluestones erected in the early stage of the monument’s construction. These results emphasise the importance of inter-regional connections involving the movement of both materials and people in the construction and use of Stonehenge.

The authors report on the strontium isotope analysis of 25 individual cremations at Stonehenge, and claim that at least 10 of the 25 cremated individuals analysed did not spend their lives on the Wessex chalk on which the monument is found. The cremated bones all came from Aubrey Hole 7, and they are radiocarbon dated to between 5180 yrs BP and 4380 BP -- placing them in the earlier stages of the monument's construction.

This is the important point about the new research technique developed by Christophe Snoek and his colleagues: "......fully calcined bone has recently been demonstrated to be a reliable substrate for preservation of the original strontium isotope (87Sr/86Sr) composition, which reflects an average of the foods eaten over the last decade or so before death, in contrast to the childhood signal represented by dental enamel. In addition, Stonehenge lies on the Wessex chalk, characterized by a well-constrained range of strontium isotope ratios (±2 SD: 0.7074–0.7090) allowing for the identification of individuals consuming food beyond this landscape."

So far so good -- this is an interesting and valuable development.

Isotope ratios were worked out for the cremated bone samples, and for 8 modern plant samples from west Wales (No controls from other parts of western Britain? Why not?) This is instructive: the modern plants were analysed "to better characterize the biologically available strontium around the quarries where bluestones originate."  What better statement of bias could there be than that?

Then the authors say: "The strontium isotope ratios for modern plants clearly distinguish the Ordovician and Silurian lithologies of west Wales (0.7095–0.7120) from the Cretaceous chalk of Wessex (0.7074–0.7090), which extends for at least 15 km around Stonehenge in all directions. Beyond this to the west and north is a large zone showing intermediate values (0.7090–0.7100) with small pockets of higher values." At this point we can already see a powerful bias appearing in the research, since it is obvious from the Figure 2 maps that vast swathes of northern and western Britain have isotope ratios that are identical to, or very close to, those from west Wales. And what on earth is Craig Rhosyfelin doing on the map? The authors could, with greater justification, have marked the locations of Birmingham, Manchester, Edinburgh or Exeter.......

This is the crucial part of the research: "The 87Sr/86Sr ratios for the cremated human remains from Stonehenge range from 0.7078 to 0.7118. There is no consistent relationship between the strontium isotope results and the radiocarbon dates. We consider the fifteen individuals with strontium isotope ratios falling below 0.7090 as ‘local’ inasmuch as they clearly reflect the chalk geology, although it must be acknowledged that this extends for at least 15 km in all directions, and further in some. With values ranging from 0.7091 to 0.7118, the remaining ten individuals (40%) could not have consumed food growing around Stonehenge alone for the last ten or so years of their lives. Those with the highest values (>0.7110) point to a region with considerably older and more radiogenic lithologies, which would include parts of southwest England (Devon) and Wales (parsimony making locations further afield – including parts of Scotland, Ireland and continental Europe – less probable). Those ‘non-locals’ with intermediate values could reflect places closer to Stonehenge or a mixture of different sources (e.g. chalk or other limestones and more radiogenic lithologies). Since measurements on bone reflect a mixture of the foods consumed over the decade or so prior to death, there is also a temporal aspect to be considered. For example, those moving later in life from west Wales to the vicinity of Stonehenge would present a signal increasingly attenuated by the consumption of local foods, while migrants arriving on the Wessex chalk more than a decade before death would effectively become ‘local’ in terms of their bone strontium isotope ratio........."

Figure 3 -- geographical assignments for two of the sampled individuals.  There appears to be no scientific reason why these two locations have been chosen -- the individuals could equally well have come from any of the other areas shown in orange on the map.

The authors admit, quite honestly, that the individuals with values ranging from 0.7091 and 0.7188 could have come from anywhere in the Palaeozoic province of the British Isles, and that the individuals with values below 0.7090 could have come from anywhere on the chalklands of southern and eastern England.  Because of this, I am completely mystified by the "geographical assignments" shown in Figure 3.  There seems to be no scientific justification whatsoever for assigning sample 288 to Craig Rhosyfelin and sample 390b to Stonehenge;  both of the individuals sampled could just as well have come from locations more than 100 km away from the named localities.

From this point on, the obsession with west Wales in the article becomes more and more apparent, and it is downhill all the way.  The paper simply becomes another exercise in ruling hypothesis confirmation, like all the other papers in which the Rhosyfelin quarrymen have been involved.  A pity -- this paper could have been so much better, and could have brought much more credit to the geochemists involved in the research.

And so the media hysteria will continue, on the BBC and elsewhere, because nobody can be bothered to read the article.  So much easier just to report on the wild extravagances of the press releases put out by those who place IMPACT at the very top of their lists of priorities.