Monday, 23 June 2014

Ethnoarchaeology - animal dung in Iraqi Kurdistan

I've just been notified of the publication of this great new paper via Google Scholar citations, as it cites my paper on lipid analysis of coprolites. That's not the only reason I'm writing about it mind you - anything dung related gets my attention, and this is one of the first papers to come out of the Central Zagros Archaeological Project, which I was involved with a number of years ago. The CZAP project aims to understand the origin and process of animal domestication and agriculture in the Central Zagros region of Iran and Iraq, and the team have also conducted ethnographic studies in modern villages in the area, in order to help interpret the archaeology. This paper by Elliot et al reports on a mix of ethnographic studies and scientific analysis of modern dung and plants.
The authors look at the dung spherulites in modern samples of sheep, goat and cows - those little spherical particles that form in the guts of animals. Despite being used frequently to support the identification of animal dung in archaeology, we still know very little about how and why these particles are produced. This paper provides some interesting data. There appears to be a variation in sperhulite production between species, with adult sheep/goat producing more than cows. However immature sheep also produce smaller amounts.  Perhaps it is related to grazing patterns? They also noted that the phytolith content from sheep/goat are richer in leaves of shrubs and trees compared to cows. Combined with the lower content in immature sheep (presumably still milk feeding), this could indicate that the diet and perhaps intake of minerals leads to an increased production of spherulites.

The authors also show that the strontium isotope signal of modern plant material varies between the alluvial floodplain and the lower foothills. It will be interesting to see further work which compares these lines of evidence - phytoliths, spherulites and isotopes - to see whether there is a link for example between the grazing locations and habits of sheep and goat compared to cow. I like the approach to this study, as it considers agriculture and animal management from a whole landscape perspective, i.e. the team are bringing together a wide range of evidence from the landscape to help understand early farming. Interdisciplinary work produces the most robust interpretations of fragmentary archaeological evidence!

Elliot et al. 2014. Figure 4 Sheep and goats daily grazing in fallow fields, on the alluvial flood plain Bestansur, Iraqi Kurdistan, summer 2012.


Environmental Archaeology
DOI: http://dx.doi.org/10.1179/1749631414Y.0000000025



Tuesday, 17 June 2014

Open access archaeological science

Exciting news, a new open access journal has been launched, specifically for archaeological science: Science and Technology of Archaeological Research (STAR) by Maney. This is in addition to the recently launched Open Quaternary by Ubiquity Press.

Joining Twitter was one of the best things I've done for my research. It has opened my eyes to a whole online network of research in my own and related areas, and has made me increasingly aware of the importance of open access research. That is, research that is freely available, rather than locked behind a pay wall. I am still unsure how this 'new' direction of publishing will impact the development of my career. As an early career researcher, I am all too aware of the need to publish in the big name (subscription) journals to get research (and job applications!) noticed by the wider community. I am hopefully taking a step in the right direction by making sure that there are open access versions of my papers available online, and hopefully will be brave enough to publish papers in the less established, or less well known open access journals in future. I think for now I will probably do a mix of 'traditional' journals and open access alternatives, making sure that anything behind a paywall has a free version via Edinburgh Research Outputs. STAR looks like a great option, as there is no article processing fee for members of the Society for Archaeological Sciences. Likewise Open Quaternary have a relatively low fee.

Via Twitter I have also learned about two interesting websites, Impact Story and FigShare. Impact Story gathers all of a researchers' outputs (not just peer reviewed papers), and collects data on things like Wikipedia mentions and shares on Twitter. This is really interesting to see, and has the potential to tell us so much more about the impact of work, rather than relying just on citations. FigShare is a website where you can upload different types of data, including things like posters, presentations and data files. It assigns these items DOIs (digital object identifiers), so that they are permanently citable in the same way that journal papers are. So, my new experimental project is to gradually upload my collection of high resolution micromorphology images, starting with the vivianite crystals I posted a couple of days ago. Hopefully these will be useful as reference material for other researchers, if you find these useful please get in touch!

Figshare profile: http://figshare.com/authors/Lisa_marie_Shillito/579003

Impact Story profile: https://impactstory.org/Lisa-MarieShillito

Monday, 16 June 2014

More vivianite!

I couldn't resist posting about this lovely micrograph, even though I blogged about this mineral quite recently. This is the same floor sample from medieval Riga, it's absolutely chock full of these iron phosphate crystals (vivianite) in various forms. The last image I posted showed the typical blue amorphous mass, here is another view, this time of a collection of smaller 'rosette' crystals, showing the monoclinic form. You can see that there is a mix of blue and yellowish/grey crystals in these rosettes. Vivianite turns blue on exposure to air, suggesting that this part of the deposit remained waterlogged whilst other parts were partially exposed. Curious that these little crystals appear to be clustering around that white area - a 'crack' in the floor.


Wednesday, 4 June 2014

Microstratigraphy and micro CT scanning

I came across these two studies in Journal of Archaeological Science recently, through Google citation alerts. It's always satisfying when my papers are cited, as it shows that there are people out there actually reading them and finding them useful! It's especially satisfying when the citing papers are as exciting as these! Both are by the same team, with lead author Hans Huisman who you may remember gave me some very useful advice through my Micrograph of the Month feature on some of my thin sections.

The first paper is "A question of scales: studying Neolithic subsistence using micro CT scanning of midden deposits" Here Husiman et al. apply micro CT scanning to thin section analysis. CT scan, or CAT scan, stands for computerised tomography, which uses a series of X rays to produce 3D images of components that are enclosed within a matrix. This is the same technique that is used in medical applications to look inside the body, but at a much smaller scale, hence the micro CT.

The application of this technique to thin section blocks is really exciting. One of the limitations of thin section slide analysis is that we are looking at a two dimensional version of deposits that are in fact three dimensional. By applying micro CT scanning, the authors have been able to provide 3D models of microscopic inclusions, within their precise depositional context. So we can see the nature of their deposition, in 3D! This is especially useful for materials such as small bone fragments and plant remains, which can be very difficult to identify if they are not at a favourable angle in the thin section slide. 

The authors conclude that this is a valuable addition to microstratigraphic studies, but not as a replacement. I think they are quite understated in the potential importance - this could be a new essential step to identify without ambiguity, the original structure of materials such as conjoined phytoliths, which break apart during laboratory extraction, but are difficult to identify in situ in thin section.With this technique we can do both - look at the specific context and number of conjoined cells, and also identify the species! 

The second paper is "Systematic cultivation of the Swifterbant wetlands (The Netherlands). Evidence from Neolithic tillage marks (c. 4300-4000 cal. BC)" and has some fantastic images of well preserved micro-laminated plant remains, that look very similar to deposits that we see in middens at Catalhoyuk. It is quite remarkable in some ways that these 2 sites, separated by time and geography, show such similar deposit types. It is very interesting from a methodological viewpoint, as it confirms that similar activities can produce similar microscopic traces, even when the depth of deposits is quite different. It also highlights how exceptional preservation, as is seen in buried deposits at Catalhoyuk, and here at the Swifterbant S4 site, can show us how much of the archaeologial record is missing from other sites.