Welcome to the third module where we delve into the field of paleodiet. This term is not to be confused with some recent and current diet fads taking the name paleo and claiming health benefits from eating a certain way. Rather this term in the academic field of osteoarchaeology means the reconstruction of the dietary practices of past peoples. As you will come to see, past peoples ate a tremendous range of different foods. We are, as a species, truly omnivorous. A lot of the variation in what people ate in the past is based upon what was available where they lived. And it's only recently that we in more developed countries have access to what is sometimes referred to as a global supermarket. There's an online optional exercise that asks you to keep track of what you ate and where that food came from. Try to figure it out in so much as possible for a day or two. For some fruits and vegetables, you may be eating a crop that was grown somewhat locally but in fact, that plant may be a new domesticate to the region. Meaning that 50, or even as far back as 500 years ago with the European arrival and colonization of the Americas, that plant did not grow there. But it does now and even if not, it can be bought here. So when we think of what people ate in the past, we should keep this in mind. On the one hand, they may have been less diversity in their diet compared to what we can find today in grocery stores. On the other hand, though, they probably made use of a wide variety of plants and foods, things we don't commonly eat today, thereby increasing their dietary diversity. And perhaps more importantly, there was the very real chance one could run out of food and starve. There was no grocery store to go to. There was only what was available in nature, plants and animals, and what could be stored. And stored without the advent of modern technologies. In the past, people were very clever in ways to store food, some of which are depicted here. But nonetheless, there were limits to this and the threat of food shortages was a reality for many people living in the past. But how do we know what people ate? Well, of course we think about what was available to them, given the climate, the region, and the species that existed. Then we can look at the remains of the foods that they ate. So for example, animal bones and plant seeds. And we can look at the residue inside of vessels used for cooking and oftentimes, microscopically or chemically, identify the foods that were present. We can look at their tools and infer what they were used for in regards to hunting, gathering, and fishing. And indeed each of these is a component of the major sub-disciplines of zooarchaeology, paleobotany and material culture studies. But in osteoarchaeology, as you've learned, we focus on the evidence that is stored in our own teeth and bones. What clues does your skeleton hold about what you've eaten? This module will introduce you to many of the ways that we reconstruct one's diet from their skeleton. We'll dive into some simple biochemistry to teach you about a common technique we use called Stable Isotope Analysis. With this technique we can take a small piece of bone, say like this. And after a lot of steps, get some numbers that tell us about the types of plants and protein that someone ate. For example, we can tell if someone ate a lot of seafood or if they were a vegan. And as you'll learn, we can also say how long someone was breast fed for. Next, we'll have a case study that investigates not so much what people were eating, but what they weren't eating. And this is via a lesion on the teeth called enamel hypoplasia. It can form when people undergo a serious episode of malnutrition or under-nutrition. Finally, we'll also have a case study about two common dental pathologies. Cavities, which we call caries, and mineralized plaque, which we call calculus, and how these have a relationship to diet. In the final discussion video of this module, we will talk about the recent trend of eating paleo. Now, while there's no doubt a discord between Western diets today and what diet our body has adapted to, you will come to see there was no single diet eaten by all people in the past. In fact, that there was remarkable diversity. It is not the case that the diets of past peoples were always perfect or ideal either. So hopefully this introductory video has given you lots of food for thought. And piqued your interest in the osteoarchaeological reconstruction of past diets. Coming up next is the video explaining the principles and methods of stable isotope analysis.