 Hi everybody, I'm Matilde van den Berg in the University of Groningen, and I will be presenting my muscle thesis results about developing a two-ferne eruption pattern scheme to estimate Asia's death in reindeer, based on recent populations from sub-art. In zooarchology, understanding the mortality patterns of animals is very important to gain insight into ancient hunting, management and husbandry practices. And the aging methods based on the dental wear and eruption patterns are quite significant because they are relatively quick, they are also non-destructive and they are also very cheap. And this method already proved this accuracy in several other studies and also for a surveyed species. Aging methods based on dental wear and eruption patterns do exist for reindeer, but they don't exist in the form of an easy-to-use scheme, such as the famous one for sheep and goat by ground from 1982, which you can see on the screen. And this one is widely used. Also the methods for reindeer have been criticized for their very shortcomings. For example, there's a high degree of subjectivity or they promote very narrow age classes, which they can't hold up to when tested. And some studies on reindeer motility even resort to using sheep goat schemes because they are so easy to use. And this really shows the urgency of developing a new, cheap, easy way to estimate Asia's death in reindeer. And this study saw to establish an easy-to-use, high-accuracy, tooth wear and eruption pattern scheme to estimate Asia's death of reindeer based on the dental aging of Svalbard reindeer. And for this, I used recent populations of Svalbard and blind tests on researchers with different levels of experience. And I had several stiff questions and I will only talk about one and a half because there is not enough time. I will talk about how easy is it for both experienced and inexperienced users to use the scheme. And what is the deviation of the estimated actual age when the scheme is applied to a biological assemblage of known age? And what can we learn from this? So I will first give you a little bit of theoretical background. Aging of mammals on the base of tooth eruption is possible because the deciduous teeth get replaced in a set of sequence and mostly also related to settled ages, although there is an age range. And the aging of reigning on the base of tooth wear patterns is because the reindeer have a salinable teeth, which means that they have dentine and animal in foldings in their teeth. And when the tooth wears away, you can see it in the result as a pattern. And previous studies have shown a strong correlation between age and the tooth wear interruption patterns, although there is also a range. Sizable osteological collections are pretty rare, but I wanted to use the reindeer menables of known age for several reasons and one of them being that an established method can then be tested for age justification. So for this study, two modern known age collections of solvents reindeer were identified and they were aged through the counting of the cemental anolea and also the eruption patterns. The first is a collection of manables from animals from the six hunting areas in the Nordiskolt region. And I visited the collection and I looked at 314 manables of 162 animals of known age. And I wanted to profoundly study at least 10 manables inside every age class and also 3 manables for every sex because then you can assess the two fair variation inside the sexes and inside an age class. But for the older age categories, because it ranges from 0 years to 17 years, there weren't so many manables, so this wasn't possible. But till about 13 or 14 years of age this was possible. And the second collection is a collection of manables collected from the reindeer's winter range on Ecea by the Netherlands Spitzwerken expedition of 1968-1969. And here I looked at 61 manables of known age, but in the process of counting the cemental anolea, the first molar was destructed, but this is not a problem because I wanted to test the scheme on this collection. And normally in archaeological samples there will also be some teeth missing, so it's actually a good practice. All the manables from the Nordiskolt collection were exempt for eruption patterns and too far. The malaria from teeth of the manables in age classes ranging from 0 to 3 years were assessed on the state of eruption. And for this I followed the codes of Eubank et al. of 1964. For example, the sea stands for the perforation in cribs visible. And you can see an example on the screen. And for the assessment of two fare, I looked at the dentine enamel patterning of the occlusal surface. So it's the upper surface of the teeth of the stadious pre-moder 4, of the pre-moder 4, the first molar, second molar and third molar. And then I constructed two schemes and those were relative and an absolute scheme based on Nordiskolt collection. And absolute scheme deals with absolute ages of the reindeer in a Nordiskolt collection. And the relative scheme deals with relative ages and this can be used on any reindeer population and can also be calibrated. I also tested the scheme for ease of applicability and intersurfer bias on 11 observants. Five observants were experienced and this means that they already worked with the scheme many times before because they are zooarchaeologists. And the inexperienced users, they worked with a scheme like the one I showed you from Grants 1982 before a couple of years back but never did it again. So they were not experienced but they knew how the concept worked. And then I gave them high quality pictures of 20 to 25 reindeer managals of the occlusal surfaces of the buccal, which is towards the lips and the lingual, which is towards the tongue side. And also the pattern code, erythron pattern codes in the descriptions. Also that I applied the schemes, both of them, on the HREA collection of the 61 managals to evaluate the performance of both the schemes. And finally I decided to draw the schemes in black and white because it makes them more objective. And the results you can see in this picture. So the results were fairly consistent between the experienced and inexperienced testers. The inexperienced testers estimated 69% of the managals within one year deviation of the real age. And the experienced testers tested 62% of the managals within one year deviation of the real age. And the deviations of more than two years are very low for both testers groups. And these results demonstrate user friendliness and also the ease of applicability of the scheme because there's a minor variation between experienced and experienced user groups. And regarding age justification, between 90 and 93% of the gels were estimated within a two year deviation of the real age. So the age justification is fairly good. It was also found that the accuracy of the scheme decreases with increasing age. And that's for the youngest age category, 92% of the managals were estimated within one year deviation of the real age. So that is fairly good. In the table you can see the age categories and then the deviations. So then I applied the absolute scheme on the HSAEA collection. And the absolute scheme scores very well for the two youngest age groups, which are 0 to 5 and 5 to 10 years old. And fairly well for the oldest age group, which is 10 to 17 years old. For the youngest age group, 96% of the estimations are within a one year range of the real age. And for the second age group, 80% of the estimated ages are within a one year range. For the oldest age group, about 60% of the estimations are within a one year range. So then I applied the relative scheme to the HSAEA collection to see how it performs. But I found a prominent difference between the two, namely the prime age group is overestimated and the young age group is underestimated. And I found this pretty striking because the absolute scheme, it performs so well. So there are two reasons why this could have happened. The first is that there are different age classes, so it's harder to compare. And the second reason is that it could be due to an inherent fault in the calculation of the ages. That hasn't been addressed before in any literature about too fair in the Russian pattern scheme, so I'm a bit puzzled. Namely, how it works is that you decide the too fair stage with some left side of the picture for a wear pattern. And then with that you can have a numerical equivalent. And then for all the T's you count them together to get a manipular wear stage. And in the case of young individuals, they still have the deciduous premolar 4, which is on the left side. When it's really worn, it can, for example, have the too fair stage of G. And the numerical equivalent of that is 13. But if you have an older reindeer, which has not the cities anymore, but the premolar 4, that has, for example, too fair stage B, then you have only numerical equivalent of 7. So when you calculate manipular wear stages, actually the younger individual comes up older. And this has never been addressed, so I think we should probably do this from now on. And then this has to be changed, but I still have to test this. So as a conclusion, it is possible to establish a relative and absolute too fair and Russian pattern scheme based on the molecular form team of the Northern Scott collection. The absolute scheme can be used to assess absolute ages of Svalbard's reindeer from the 6th century ground and the grounds and relative scheme can be used to estimate the age or death of any reindeer but only relatively, but can be calibrated. The absolute scheme scored very well for ease of applicability and age justification and there was also minor variation between the experienced and inexperienced users and this proves the accuracy and also the user friendliness of the scheme that we developed. And the best results are yielded within the youngest age categories, which is 0 to 5 years old. And the application of the absolute scheme to the Azure collection yielded even better results with about 83% of the mannables being estimated within one year deviation of the real age. And the majority of the Azure collection didn't even have a first molar so it also proves the utility of the scheme for molars or for mannables with one teeth missing which is often the case in archaeological assemblages. And lastly, the calculations from the Asia should be changed for the serious premolar form and this problem should be addressed in other studies concerning two fare and two eruption schemes. I would like to acknowledge many people of whom my supervisor, Shanaan Tiavila, the first one and also the Katerine van Tussbuk Foundation for granting me a scholarship so I could go to Oslo and visit a collection and also a research school archon for giving me the archon conference subsidy so I can present my results to you.