ossamenta: Weasel skull (Default)
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Pathology is probably one of the more trickier parts of osteology. It's relatively easy to see that something is wrong on a bone, but to actually pinpoint it to a type of disease... Occasionally, you are lucky, but that's usually more to do with very particular pathologies from a particular type of disease. Often, the bony changes could have come from several kinds of diseases*. Sometimes it's not even a disease, just age related wear and tear. Of course it doesn't help that as opposed to human osteologists we usually only deal with single fragmented bones and not an entire body. Therefore I was very glad that I could go to the Professional Zooarchaeology Group's pathology themed meeting last month, to discuss these things with likeminded people.

*: Check veterinary medicine, I hear you say? Well, these days animals are often either treated or are put down before the disease progresses to stages where it affects the skeleton and not just the soft tissue. Consequently, veterinary medicine books are almost exclusively focussed on identification of disease from changes in soft tissue.

The meeting at the Archaeology department in Leicester University started with Richard Thomas giving a long talk on what to do with pathologies: how to record them, and diagnose them. The brief gist of it:
- Recording: Describe it! Then you can compare with other sites, and the pathology identification can if necessary be changed later. Describe the precise anatomical location, the size and shape of the lesion, if the pathlogy involves new bone growth or bone absorption, whether any new bone growth is porous (new) or smooth (old). If possible, use a scoring system to make it easier to compare.
- Diagnosing: difficult with disarticulate remains, but try to identify a broad disease type (infection, fracture, degenerative joint disease etc). For articulate remains, try to pinpoint any possible diseases further. Use the five stages described in UN's Istanbul Protocol to tell how secure the diagnosis is. (The Istanbul Protocol deals with the investigation and documentation of torture, and since this could be evidence for war crime trials, the diagnoses needs to be very clear on how likely it is that the damage could be caused by torture).

There was also a couple of case studies:

- Richard's and Jessica Grimm's study on bony ridges on sheep metatarsals, believed to be associated with hobbling, repeated impact trauma from walking on hard surfaces, etc, came to the conclusion that this is a natural age related change in the bone, after having analysed several skeletons from free ranging sheep with a known history.

- Richard also studied foot bones from the feral Chillingham cattle, and found that some bony changes in the foot bones are age related, whereas others must be connected to the use of cattle for ploughing. Earlier studies* had assumed that all these changes were related to cattle as draught animals, but if you have only study bones from old oxen, you can't tell which changes are age related and which were caused by the extra strain on the body from pulling ploughs and carts.

- English Heritage is doing a similar thing with sheep, studying how the nutrition level, sex, age at castration, age at breeding and age at death influences the timing of tooth eruption, bone fusion, pathologies etc. Fay Worley reported on rib fractures, often considered to be evidence of animal abuse. However, since the flocks were not handled by humans, or at least had minimal interaction, the rib fractures present in the skeletons (16% of the sheep had at least one rib fracture) must have been caused by other sheep, or by falls. Since rib fractures were much more common in rams than in ewes or castrates, they think it might be connected to rams butting each other, probably as a dominance behaviour. The sheep project is ongoing, so I'm sure there will be many interesting reports coming from it.

- Jim Morris did a synthesis of pathologies from Roman London, making use of Museum of London's archaeology database which has been in use since the 1980s (over 500,000 records!). Since it's a single database, with consistent recording methodology it has potential for large overarching analyses. However, pathology was a bit tricky, since this (and butchery) had been recorded using the STRING method, which only allows for 12 key strokes. Lots of abbreviation, which varied between recorders... Some records were indechifferable. However, most could be figured out. Patterns of variation between species could be seen (for example, fractures on chicken bones occured mostly on wings and lower legs, whereas fractures on dog was found all over the skeleton), but due to the recording methodology it would require more time to do a proper analysis. This would likely entail going through every pathological bone and re-recording them properly (not using STRING).

There were also a hands-on session with lots of pathologies, some identified, some not. Lots of cool stuff! I brought along the horse teeth, but no-one had seen anything similar before.

Next time we're going to University of Lancashire to talk about horses, donkeys and mules (possibly zebras too).

*: see for example Bartosiewicz et al. 1997 Draught cattle: their osteological identification and history. Koninklijk Museum voor Midden-Afrika, Annalen, Zoologische Wetenschappen Vol. 281. THE work on bone changes on cattle foot bones, with a good scoring system.


ossamenta: Weasel skull (Default)

January 2019

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