Welcome to the first case study of the activity reconstruction module. Where you will learn about musculoskeletal markers called entheses. These are areas where tendons attach to bone. Research has shown that strenuous and repetitive activities can cause the appearance that is the morphology of these origin or insertion sites to change. This can tell us which muscles where being use the most and therefore what types of activities were being the most frequently performed. Some researchers have dubbed the prospect of identifying an individual's occupation from the skeletal record, the �holy grail� of osteoarchaeology. So first, let's explain a bit more about these musculoskeletal activity markers. As noted an enthesis is simply the attachment site of a tendon and there are two forms of entheses, fibrocartilaginous and fibrous. Fibrous entheses change appearance in less complex ways than fibrocartilaginous entheses. Partly because of this more research has focused on the fibrocartilaginous entheses as these are thought to be more representative of activity. Over the years osteoarchaeologists have given quite evocative terms to entheses, including musculoskeletal stress markers, skeletal markers of occupational stress and enthesopathies, a combination of entheses with pathology. In this video we will use the term entheseal changes, abbreviated as EC. As it's the name that's most commonly used today and in order to avoid inferring anything about the cause of their appearance. So the theory that entheseal change relates to activity relies on the assumption that the morphology of an enthesis is influenced by repeated use of a particular muscle or muscles as a result of habitual activities. Thus causing bone remodeling to occur as a response to mechanical stress. And evidence to support the relationship between activity and entheseal morphology certainly exists. But we have to keep in mind there's actually a multifactorial etiology behind entheseal change. So, It's not reflecting activity alone, especially important is age related change as well as sex and disease and one's propensity for bone modelling and remodelling unto itself mediated by a large number of factors. As well there's a lack of clinical data, looking at the relationship between muscles and entheses and this leaves a lot of room for valuable future research. One way to improve our understanding of how changes in the morphology of muscle attachment sites come about and should be interpreted is to investigate and compare different populations. And indeed many such studies have been conducted, sometimes including individuals with a known occupation. Solid comparisons however, only possible with a consistent methodology which is something we will discuss now. In 1995, Doctors Hawkey and Merbs published a landmark study on Hudson Bay Inuit populations that became the driving force for musculoskeletal marker research in osteoarchaeology. Their initial system for scoring entheses was updated by Dr. Mariotti and colleagues in the 2000's, and has become widely used. This Mariotti Method uses three criteria to score entheseal change, namely, robusticity, osteophyte formation, and osteolytic lesions. The method was developed for 23 fibrous and fibrocartilaginous entheses with descriptions and pictures of robusticity scores for each. Now I expect some of these terms are confusing to you. Even osteoarchaeologists not specializing in this subfield have to spend some time getting familiarized with what these terms mean. If you'd like you can watch a short demonstration video explaining what these terms mean in more detail with examples drawn from our own laboratory collection. This is an optional video with our PhD student Jessica Pauler. Recently, a group or Entheseal Change researchers including the aforementioned Mariotti united in something called the Coimbra group. And this was to create a standard Entheseal scoring method solely applicable to fibrocartilaginous entheses. This new Coimbra group method, is in its final development and testing phase, but as of 2015 it worked as follows. A fibrocartilaginous entheses is divided into two zones. Zone one being the edge of the enthesis, and zone two being the rest of the surface. For zone one, two traits are evaluated, bone formation and erosion. And for zone two, bone formation, erosion, fine porosity, macroporosity, and cavitation are analyzed. It's not yet known which method is best as not only have clinical studies yet to be performed but few studies have assessed the similarities and differences of the methods� outputs. Now that you know what Enthesis are, the two main scoring systems that have been used by osteoarchaeologists and are aware of the rather young state of the field. Let's turn to an example of this type of research. We return to the site of Middenbeemster in the Netherlands, shown here. Recall that we excavated the cemetery in 2011 at the request of the adjacent church and have been undertaking a range of osteo- archaeological analyses of the almost 500 skeletons we uncovered. Most of the skeletons come from the 19th century. And important here is that the inhabitants of this rural Beemster area where mainly occupied with dairy, that is cattle farming. And had not yet been affected by the industrial revolution. So most labour was manual or the with the aide of stock animals. And my PhD student Jessica Palmer will now talk about the entheseal change research she has conducted on this population. Jessica, thank you for joining us today. Can you tell us about your motivation to investigate activity reconstruction markers in this population? >> Well what inspires me is that Middenbeemster is such a beautiful capsule collection of rural village population. These are very well preserved skeletons and we know a lot about their background, so the kind of activities that they would have been doing. And also we have all age categories available for a comparison. >> What methods did you use to try and reconstruct what their activity patterns were? >> Well I used the Mariotti method, which I applied to the larger muscles of the upper arm, the chest, and the back. And the reason I chose these muscles is I wanted to avoid the lower limb because it's involved in locomotion, so it's much more complex. And I wanted to look at the large muscles which would be involved in farming activities. >> I see. And what were the results? >> Well we had four very interesting results from this study. So first off, we saw a very clear correlation with age, which is not surprising because the longer you live, the more time you have for all these little changes to start building up. Secondly, we saw that there was no clear signs of social differentiation within this population. They were all doing quite a fair amount of physical activity. Thirdly, we saw that the larger muscles of the chest and the back were actually often more pronounced on the left than on the right. And this seems counter intuitive but it actually makes a lot of sense because if you're using farming equipment such as a shovel or a hoe, you're actually guiding the movement with your right arm but your left arm is doing the brunt of the force. And then lastly and I think this is the most exciting result, is we saw a difference in muscle use between males and females. Males had more pronounced entheseal changes for almost all muscles except the triceps. And the triceps is that muscle that runs on the lower side of your arm up to your ulna. Now what this tells us is that males were not necessarily always doing more strenuous physical activity than females. They were just doing different things. And activities that females might have been doing which would cause this triceps to be so pronounced. Could be things like milking cows, or maybe using a scrub board for doing washing. >> Very interesting. So one final question then. What types of research do you think need to be undertaken in regards to these entheseal changes? To allow this method, this research to really take off within osteoarchaeology. Well we'd need to do a lot more research on two levels actually. We need a lot more fundamental research into the clinical aspect of which things are normal variation at a muscle attachment site, which things are age related, and which things are actually activity related. And then also at the osteoarchaeological level, we need a lot more collections to be analyzed. We basically need to get a very big data set so we can get a grip on what is normal enthesial change within each context and then we can use that for further comparison. So a lot more needs to be done. >> I agree. Thank you very much for joining us and sharing your research with us today. >> Thanks for having me. >> In this video, you've learned about entheseal change research, an avenue of activity reconstruction research and osteoarchaeology. You've learned what factors influence entheseal morphology and about the two main methods we use. You then heard about a case study on a rural 19th century Dutch population that has contributed to our understanding of their activity patterns. Coming up next is the second case study where you were learn how a particular pathological lesion that occurs in synovial joints, osteoarthritis, can be used to reconstruct the past activity patterns. See you soon.
