Entheseal Change Analysis and the Potential for Zooarchaeology

Entheseal Change Analysis and the Potential for Zooarchaeology

            I have recently been learning about entheseal analysis of human skeletal material. Entheses are locations on bone where tendons and ligaments attach, the surface of which can vary between individuals due to repetitive stress on the muscle being reflected on the muscle attachment on the bone. Entheses have been analysed in bioarchaeological contexts to look at reconstructing life histories of individuals, by looking at whether any changes are present at particular entheses sites, and attributing these changes to a certain physical activity.

An example of this is Yonemoto’s (2016) study of Japanese populations in the 15^th to 19^th centuries, where the effects that different occupations had on entheseal change was assessed. The analysis showed different levels of entheseal change for different occupations, due to different repetitive areas of stress on the body occurring depending on what their occupation involved e.g. Fishermen who were known to load and unload boats had high levels of entheseal change in ankle and foot joints. However as I am more interested in zooarchaeology rather than human osteology, although I found the case studies very interesting, I immediately began to think of how this could be applied to animals.

Figure 1: Yonemoto’s study of entheseal changes in Japan discovered individuals occupations such as Fisherman, which was backed up by other evidence such as paintings.

To check whether this has been done before I conducted a quick literature search and found a distinct lack of articles applying this technique to animals.  One study I did find by Ninimak and Salmi (2014), looked at entheseal changes in reindeer. The study looked a Reindeer that performed a range of different activities including free roaming reindeer, species kept in a zoo and draught animals and studied the entheses using the same methods you would apply to a human skeleton. The results showed differences between all uses of the species. Differences between zoo and free roaming reindeer were found in the upper arm bones, interpreted as different feeding techniques. An overall higher rate of entheseal change across all bones in the free roaming reindeer was also found, and was  interpreted as due to their large scale migration patterns causing repetitive strain on certain muscle attachments. Further patterns were shown in the draught reindeer with increased entheseal change in the hind limbs, which was interpreted as repetitive strain from pulling weights behind them e.g. a sleigh.

Figure 2: Analysis by Ninimal and Salmi showed evidence for Reindeers being used to pull weights behind them e.g. Sleighs. Photo: Wikipedia

                  I believe that if this technique is applied more frequently to other species of animal, zooarchaeologists could discover a lot more about past human-animal relationships. As shown in the Reindeer case study, analysis of entheses can show what activities the animal undertook, which is usually invisible archaeologically. Examples of this could be the analysis of cattle entheses which may show changes in upper limb bones due to ploughing, which is rarely seen archaeologically. Other possibilities may include the analysis of dog remains to identify whether they were used for hunting over long periods of time or traction e.g. sleigh pulling, or horses which may face entheseal change during horseback riding.

                  Although problems with the recording of entheseal changes exist, due to all existing methodologies only relating to human bone, the simple recording of the presence or absence of entheseal change may give information about the animal’s life history, and what it was used for in the past.

References/Further Reading

Ninimaki, S. and Salmi, A K., 2014. Entheseal Changes in Free-Ranging Versus Zoo Reindeer—Observing Activity Status of Reindeer. International Journal of Osteoarchaeology. 26 (2). 314 – 323.

Yonemoto, S., 2016. Differences in the Effects of Age on the Development of Entheseal Changes Among Historic Japanese Populations. American Journal of Physical Anthropology. 159. 267 – 283.