Welcome back to the last case study of this module. We're going to switch gears from talking about how we can see evidence of activity in the bones to exploring activity- induced dental modification. Abbreviated as AIDM, basically meaning evidence of people using their mouth as a third hand, or teeth as tools. Think about it for yourself. Do you find that you use your mouth and teeth in certain activities? To hold something, perhaps, while your hands are otherwise occupied? Or to grip something, or as an anchor or vice when trying to pull something apart? There is a great Dutch commercial, that we've put the link to here, that quite perfectly demonstrates what we mean. And on the online discussion forum we ask you comment upon the activities in which you use your teeth or mouth as a third hand. One thing to keep in mind, going forward, is the distinction between this kind of activity induced dental modification, which occurs as a side product of certain activities. And intentional cultural modification of the teeth. As interesting as this latter practice is, it's not what the focus of this video is upon. So let's think about this for past peoples, who usually had less sophisticated tools and technology available for the processing of materials or to aid in the construction of composite complex objects. It should come as no surprise that the mouth and teeth were quite heavily used, for example, as a brace, a vice, or to hold an instrument, to mould, shape, crush certain materials. In one well known example, Dr. Charles Merbs studied the skeletal remains of the Sadlermiut Inuit in Canada from the early 1900s, along with historical ethnographic accounts of their life ways. It was shown that the women made extensive use of their teeth to soften animal hides, for example in softening frozen animal hide boots. The women also made rope out of sinew by processing it with their teeth. And men, on the other hand, used their teeth for lot of vice grip tasks, for example, in holding a sled runner while it was being bent into place. For our case study we returned to Siberia, to our hunter gathers from the Lake Baikal region that you've come to know rather well. In case you're fuzzy on the details, recall we're looking at two different biologically and culturally distinct populations that lived in the region from around 9000 to 3000 years ago. The earlier Kitoi and later ISG. In my research I observed that a lot of these individuals had these strange grooves in their teeth, on the chewing or occlusal surface, that would not have formed merely from the normal chewing of food. These people had to be doing something extra to create these grooves. And the first step in figuring out with these grooves were was to document and describe them. So to measure their size, note where and in whom they were occurring. And here are some results of those analyses. Out of 123 observable individuals, 25, or just over 20%, had these occlusal grooves. A total of 51 grooves affected 57 teeth. In most cases they were more common in females than males. But, we do suffer from a small to even absent number of females at some sites, so our data is incomplete. Occlusal grooves are most common in middle adults. This suggests it took many years of repeated activity for them to form. As a whole, occlusal grooves were more common in the Kitoi peoples than the ISG. But it's really this one site, Khuzhir-Nuge XIV, that is bringing down the ISG average. The other two ISG sites also had a quarter or more of the population with occlusal grooves. These grooves affect the front teeth mostly, the incisors and canines. And it appears that they are radiating out from the oral cavity. They are roughly evenly distributed between the upper and lower jaw. Finally, if we compare sites that are located along the shores of the lake to those located along the river, regardless of time period, we find a much higher percentage of grooves in peoples from the riverine sites. And this suggests that maybe people relying more on riverine resources had a greater need to produce whatever it was they were making. Through analyzing the microscopic orientation of the striae within the grooves, we also can gain information about how they were formed. So I made casts or impressions of the teeth with grooves to take it to a powerful scanning electron microscope. And in this figure you can see an occlusal groove running roughly vertically, from upper middle left to bottom middle right, at just about 100 times magnification. Notice how the striae within the groove are orientated parallel to the groove itself. This indicates that something was being pulled back and forth repeatedly along that spot. But in this next figure, the occlusal groove runs diagonally from the upper right to lower left, the same level of magnification in the last image. But notice that the striae in this groove are a bit different. You can see both striae running parallel to the long axis of the groove, but also some that are perpendicular. And this suggests that the material that caused the groove was being twisted, as well as run back and forth lengthwise. So with all that information, what can we say? Clearly whatever was being done with the teeth was relatively common. And while overall more common in females, it certainly wasn't a strictly gendered task, as many males had grooves too. The activity that fits best with these data is the use of the mouth and teeth in the production of rope and string called cordage. This cordage would've had a wide range of purposes, from use in weaving baskets and containers, sewing clothing and boots, fastening together tented housing. Tying together separate components of composite tools like harpoons. Constructing snares and fowling nets. A part of smoking and drying racks for meat and fish. And we think especially important for these people is the creation of fishing line and fishing nets. Many tasks would have been considerably aided by a steady supply of cordage. Ethnographic and experimental archaeological research has shown that cordage can be made from certain plant fibres, as well as animal products like tendons. In the Lake Baikal region, plants such as dogbane, a type of hemp, cattail and nettles, as well as the inner strands of tree bark called bast, would have been excellent sources of the raw materials to make cordage. This quote from the observation of an indigenous Siberian group from the 1800s illustrates the idea. One can imagine that both men and women would be engaged in these tasks and that a lot of the population would be involved. One can easily understand why the appearance of the grooves would vary, depending upon the way and type of cordage that was being produced. Why evidence for this activity is absent from the Early Bronze Age site of Khuzhir-Nuge XIV remains a mystery, but maybe a new technological advancement's occurred. In this video, you've learned about something called activity induced dental modification, which is the fancy name given to marks that can occur in one's teeth as a result to be using your mouth and teeth as a third hand. Essentially, your teeth as tools. In our Siberian hunter-gatherers, the mouth and teeth were likely very important in the creation of cordage, which was then used in a variety of tasks. We think probably, especially in fishing, maybe along the rivers. Coming up next is the short discussion video for week four, where we come back to the big questions about activity.
