Fewer words are more enjoyable in Scottish slang than 'jobbie'. So it's a special pleasure for me to get to work on fossil poo, and legitimately say 'jobbie' when talking about actual science.
A couple of years ago I micro-CT scanned a bunch of jobbies at the University of Edinburgh. The scans were carried out by Ian Butler, who runs the scanner there, and the honours student I was supervising, Carla Willars. It was part of a project I devised and was co-supervising with Stig Walsh at National Museums Scotland. We were scanning scat from across the country: squidgy fresh ones, shrivelled-up old ones, and some truly ancient ones, looking at bone preservation in poo (as you do).
|Skara Brae (Pic: by John Allan, via Wikipedia)|
The CT scans showed that the coprolites contained a smattering of vertebrate bone shards. Sharing them with colleagues at National Museums Scotland, we decided to try and work out who or what deposited these jobbies, and what animals the bones inside them belonged to. It blossomed into a larger analysis led by Andrzej Romaniuk, and we published the results recently in Archaeological and Anthropological Sciences.In our paper we combined traditional and modern methods for analysing specimens. As well as using the original CT scan data, we included both regular microscopy and scanning electron microscopy. The latter is basically a microscope that looks at specimens using a beam of electrons, rather than just visually through regular lenses. It allowed us to look at the surface of the coprolites and the bones that were sticking out from them, and see fine details such as the damage that results from digestive acids. Another analysis we carried out was to examine preserved lipids and proteins. This involved taking small samples of one of the coprolites, and analysing it using a mass spectrometer, which can identify what kinds of proteins are in a sample. We can them match them to an organism.
|A scanning electron microscope image of a vole upper jaw bone and teeth, found among the coprolites at Skara Brae.|
Using all of these methods, we discovered that these wee jobbies belonged to a prehistoric pooch - one of the many dogs that lived with humans in Neolithic Orkney. The bones inside the coprolites - and found alongside them during excavation - included chunks of cancellous bone, the spongy tissue that makes up the 'honeycomb' structure inside bones. There were also pieces of the hard outer bone coating, called cortical bone, and some teeth. Some of the larger fragments could be identified as belonging to hoofed animals like sheep, which we know were kept as food by the inhabitants of the settlment. But there were also very small bones and teeth belonging to voles.
|Ilustration of Skara Brae in the Neolithic, by Colin MacNeil. Note the dog sitting by the old man.|
These results suggest that people in Skara Brae were either feeding their dogs on butchery scraps, or the dogs scavenged them from midden heaps (or both). The remains of voles in their faeces shows they ate them too, perhaps helping to play a role in pest control. As well as this, our study showed the power of combining multiple techniques when investigating specimens - and hopefully minimising the destruction or damage of samples during scientific analysis.