Monday, 16 February 2015

Faecal lipids and fungal spores as proxies for ancient pastoralism

I was recently alerted to this interesting new paper (open access!) through Google Scholar citation alerts, which is a very useful service for finding out when your papers are cited by other authors (in this case my 2011 paper on faecal lipid residues at Catalhoyuk). The authors studied a sequence of lake sediments from Lake Igaliku in SW Greenland, looking at changes in the quantity of DOC and fungal spores. DOC is a bile acid (deoxycholic acid), and is found in both human and ruminant faeces, but at a higher concentration in ruminants. Humans have higher amounts of LC (another bile acid, lithocholic acid). Interestingly no LC was found, suggesting that the DOC comes entirely from herbivores (and that the runoff 'polluting' the lake is largely agricultural, rather than coming from settlement sewage waste).

The fungal spores that were found are from coprophilous fungi - i.e. fungi that grow on faeces! The amount of DOC present correlated with the number of fungal spores, with both being at their highest during periods of intensive human occupation, firstly in the Norse period, then later in the 1920s.
Also of interest is that the 'background' levels of DOC and spores that were present prior to Norse occupation, and interpreted as coming from wild herbivores, dropped significantly after Norse abandonment, suggesting that the wild herbivore population had disappeared, or at least dropped significantly.

Sporomiella photo by Alain Brissard
The only downside to the paper is that it doesn't include a representative GC trace showing the DOC, which I find quite useful for visualising the quantities that were recovered. There is also a peak in fungal spores around AD 500 that does not have a corresponding DOC increase, which suggests there may be something a little more complicated going on than a straight correlation between the two. There is no discussion of depositional pathways for the DOC or fungal spores, perhaps this is related to changing hydrological conditions within the lake? The quantification is also different to what I am used to, and it is not entirely clear how the flux rates were calculated  - I would have preferred to see the absolute quantities recovered. But still, it is a great little case study in how you can integrate different analytical methods to provide multi-proxy evidence for human activity, and proposes some interesting hypotheses that can be investigated further through archaeology.

I've never looked at spores much myself, but maybe I need to start, I found a lovely photo of one of the major dung loving fungal spores, Sporomiella, which amusingly looks rather like a mini coprolite. For more reading on the fascinating world of dung fungal spores and photos of other types, check out this website, Mykoweb!

Tuesday, 10 February 2015

Can there ever really be such a thing as single context archaeology?

I made my first ever video this week. It is an attempt to visualise a concept that can be difficult to express - the relationship between micro (and sub-micro) stratigraphy that we can see under the microscope, to the macroscale deposits that most (non-micromorphologists) are familiar with in the field. It is hard to imagine something you cannot see, and as an archaeologist who has the privilege of being able to examine the 'invisible' archaeological record, I want to be able to show others these insights, which can have a significant impact on the process of interpretation. It is this thought that is the focus of a short article that has just been published on Then Dig, a peer reviewed blog hosted at Berkeley. The thoughts that I express there are a short glimpse into the theoretical (and practical) problems that I ponder frequently, and on which I hope to write something more extensive in the future.

To come back to the video, I am quite pleased with how it turned out. I made it in PowerPoint, and it isn't quite what I wanted to achieve in terms of 'zooming' between different scales, but hopefully it achieves what I was trying to show - that the complexity of the archaeology record increases the closer you look. Hopefully the first of many videos as I get better at it!

The video shows firstly a section through a Neolithic building at Kamiltepe, Azerbaijan, followed by a photo that zooms in to the section, where you can almost make out the series of plaster floors. The next image shows a micromorphology block that was taken through the section and set in resin - here you can begin to see that things are a little more complicated than they appear in the field. Within a block of 15cm of sediment, we can already see at least 5 individual layers, each only a few cm thick. And then we see 3 different views down the microscope - the first shows a floor surface, which you can make out as a very defined horizontal line, overlain by a yellowish fragment of bone and microscopic charcoal. A layer of dirt! The second shows  another layer, with tiny chippings of lithic microdebitage, perhaps from where someone sat retouching of a stone tool. The final image shows a later layer, again only a few mm, with lots of yellow bone fragments and organic remains. This building had rather dirty floors!

Can there ever really be such a thing as single context archaeology?






Tuesday, 3 February 2015

Microfossil of the Month: Sponge Spicule

Something a little bit different - this month I have an image of a siliceous sponge spicule! This show up occasionally in my phytolith slides, and are very distinctive. Sponges, or poriferans to give them their scientific name, are characterised by an unusual feeding system that involves drawing water in through little pores in the outer walls, and filtering food from the water as it moves around their bodies, before being pumped back out again. This flow of water occurs in one direction and is driven by beating flagella. Sponge spicules provide structural support and protection from predators. They come in all sorts of shapes each with a different name - the single spike shape that you can see looks like a monaxon, though it is also possible that is has broken off a larger 'polyaxon' type.
The formation of spicules seems to be better understand than that of my other favourite siliceous microfossil, the phytolith, and is controlled largely genetically, but with environmental conditions (i.e. the amount of silica available in the environment) having an impact on whether a genetically determined spicule type is expressed. This example comes from the same ashy midden deposit as last month's reed phytoliths. If we can identify the genus or species that the spicule comes from then it may help understand where the reeds and other plants were coming from, or even the type of environment, and is also a good indicator of water pollution.
I am not an expert on them so cannot identify them definitely beyond a general category, though this example does appear similar to the 'megasclere' spicules of freshwater sponge Spongilia lacustris, or perhaps Ephydatia fluviatilis. If any readers have suggestions I would love to hear them! It makes sense that we have freshwater sponges given the location of the site that it is from, Boncuklu, would have been close to a range of wetland environments in the Neolithic. Knowing more about the species and the ecological requirements would be very interesting.

Monday, 2 February 2015

Who Ya Gonna Call? 4 Real Life Women in STEM who would make awesome Ghostbusters

I read on the interwebs recently that the new Ghostbusters are women! I also read that some people thought this was "unrealistic". So I thought I would check out the original characters and see what is so unrealistic about them being played by women. Why am I blogging about this you may ask? Where is the archaeological connection? Well, it so happens that one of the original Ghostbusters did a PhD in Egyptology! Now it's been many years since I watched the films, and I was of an age where I didn't take in the details of people's professions and whatnot, but that's pretty awesome. And ghosts, you know, archaeology, dead people, cursed artefacts etc. There's a connection in there somewhere.

Dr Watt, Prof Jackson, Prof Ikram & Prof. Ferlaino
The original dudes were parapsychologists. As psychology is a rather large field, I wasn't sure where to start, but I managed to find Dr Caroline Watt, at my own University of Edinburgh, who researches the psychology of paranormal beliefs and experiences, and literally wrote the textbook on parapsychology! She is a founding member of the Koestler Parapsychology Unit, and is a past president of the Parapsychological Association. You can watch a short video about her research here.

Parapsychology also has links with quantum physics, and although I can't quite work out what Egon Spengler's specialism is, he apparently provides the theoretical basis, so quantum physics it is. Professor Francesca Ferlaino, professor of atomic physics at the University of Innsbruck and the Austrian Academy of Sciences, works on ultracold atomic and molecular gases, and something to do with exotic states of matter. I literally cannot say more than that, as quantum physics makes zero sense to me. But it's exciting and inspiring nonetheless - this is the very stuff the universe is made of!

Quantum physicist two, Professor Shirley Ann Jackson, PhD in Theoretical Elementary Particle Physics from MIT, and International Fellow of the Royal Academy of Engineering. Also worked on crazy invisible particles, all over the world, from the Fermi National Acceleroter Laboratory, to CERN in Switzerland, and has been chairman of the US Nuclear Regularory Commission. She is currently president of Rensselaer Polytechnic Institute, the oldest tech research university in the US.

Winston Zeddemore, ex-marine, has a PhD in Egyptology. There are so many women Egyptologists I didn't even know where to start with this one. One of many women doing amazing work in this area is Professor Salima Ikram, at the University of Cairo, who has a PhD in Egyptology and Museum Studies from the University of Cambridge. Author of many books on ancient Egypt and leading expert on animal mummies, she is also frequently seen on the TV on programmes about ancient Egypt and archaeology, and she was an advisor for The Mummy movie. in this sense she is similar to Peter Venkman, the 'public face' of the original Ghostbusters team! It's true that I couldn't find a female marine with a PhD in Egyptology, but my googling for female marines with PhDs turned up a lot of interesting women working in marine biology...

Who ya gonna call? Not only was it easy to find a team of 4, I actually had to choose which ones to include as there are lots of amazing women working in psychology, quantum physics and Egyptology.  And most of them don't have Wikipedia pages, which is now on my to do list for the next women in STEM edit-a-thon.