Welcome back to the last instructional video of this first module. We will learn about the methods to reconstruct an individual’s stature, also known as their height, from their skeletal remains. First let's consider why we are interested in knowing someone's stature. The world is filled of short people, and tall people, and lots in between. Between, as well as within, populations, considerable differences in height are found. And these are considered normal in the sense that they're not associated with an abnormal endocrine change, or disease or malnutrition. Variation in height is distributed in a normal bell curve, with lots of people in the middle and fewer and fewer towards the ends as is depicted here. And while on average men are taller that women, there is a lot of overlap between the two. A lot of variation in your height depends upon your genes. Research suggests that 60 to 80% of your height is determined by genetic factors. By the genetic predisposition you inherit from your parents. Who in turn, inherited it from their parents, and so on. But, as many of you know the realization of one's genetic height potential is dependent on your environment. Mostly upon a growth period with adequate nutrition and good health. So, one reason osteoarcheologists are interested in stature is to compare the averages of different populations to see if one experienced a more harmful growth period than another. In particular, osteoarchaeologists have focused on comparing populations before and after major cultural changes. For example, before and after the Industrial Revolution or before and after a period of conflict or war. And in that way, we can infer the presence and extents of environmental stress that the population experienced. In historical and modern populations, events such as war, food scarcity, lack of access to healthcare and poverty have a clear negative impact on someone's height. We will visit one application of stature research at the end of this video, when we are fortunate to have an expert human osteology researcher and medical doctor, Professor George Maat join us. He will speak to us about his stature research on Western European populations that spanned over 2,000 years. First, though, lets explore the methods we commonly use to reconstruct stature. So if you think about all of the bones in your body that contribute to your height, from your feet up to your head, there are thirty in total, most in your spine. And you have an estimate of the amount of non-skeletal tissue between these bones. For instance, the intervertebral disks that exist between each of your vertebrae. You could measure each one of the bones, add in the soft tissue estimate, and then achieve a stature estimate. And indeed, occasionally this is done in osteoarchaeology. But in most instances, not all of the bones are present are well enough preserved to use this method plus it's quite time consuming. So usually osteoarcheologists will take measurements of the length of one or a few bones especially bones from your legs and your arms as these give the highest accuracy. And we'll plug these measurements into something called a regression equation. and Voila! a stature estimate is produced. So how does this actually work? Well it's actually quite simple. Scientists have measured the body proportions of thousands and thousands of individuals, from different populations the world over. And it's been shown, since the days of Leonardo Da Vinci, in fact. You'll likely recognize his Vitruvian man. That there's a strong correlation between the size of one body part and the size of another body part. For stature, it's been shown that size of one bone is strongly correlated with the final size of an individual with their height. This is been shown for example by Dr Mildred Trotter whose regression equation which we will use shortly. Because the leg long bones, the femur and tibia especially contribute the most to height, they have the strongest correlation with height. So we can take the length of the femur for example, plug it into a regression equation, an equation built from these data, on the relationship between its size, and a person's height, and we'll receive an estimate. The estimate won't be an exact match of course. There's a plus/minus factor that at least a few centimetres that must always be kept in mind, but we can usually get pretty close. It's important to keep in mind that we must use population specific, regression equations as much as possible because different populations in geographic groups have slightly different body proportions, which if not taken into account, will decrease our accuracy. And also one must use sex specific regression equations to account for differences in the relationship between different body proportions for males and females. Now if you want to see this in action, there is a short optional video that you can find in the course documents. Where Anne-Marijn will show you have to properly measure and a bone and apply the appropriate regression equation to achieve a final stature estimate. And now on to the interview. It is now my pleasure to introduce to you a renowned human osteoarchaeologist and medical doctor, Professor Doctor George Maat. Professor Maat, thank you for joining us today. Professor Matt spent many years compiling and collecting stature data from male individuals from 21 different populations throughout the low countries. If you're not familiar with this region, it's depicted on this map. And these populations came from the period from AD 50 to 1997, thus over 2,000 years worth of data. This paper was published in 2005 in the International Journal of Osteoarchaeology and you can see the title of the paper here. Professor Maat, can you please tell us about the main findings of your research? Of the main findings, I think the main finding was that although we expect it because this is happening nowadays, that people are getting tall all the time, that they had been doing so for the last 2,000 years. But in fact it showed, when putting all data together and putting them in a graph, that the dominating action has been that we were getting smaller for over 1,800 years. And then with the Industrial Revolution halfway to 19th century, only from that moment, we increased in length with an incredible more than 17 centimetres in 150 years. And that was quite a surprise, yes. And we think that is the result of decreasing and later improving social economic conditions of the populations. There are various parameters from what we could conclude that is. >> Now you have to make stature data from a number of different methods comparable. And also take into account that we shrink slightly as we age. Can you briefly explain to us how you were able to accomplish this? >> Yes, that is to measure directly or by correction. What the stature was of the males when they were in the ages between 20 and 30 years because we assume that before the 20 years they may still be growing and after 30 years they may be shrinking or for sure they were shrinking. And we could compensate for that because we have formulas to do that. The measurements have been taken directly from the skeleton as people were found inside of the grave. They have been calculated if we only had a bag of bones from their long bones. And we have of course also been measuring from the living people by having their standing heights straight away. >> And finally, in the 11 years since your study was published, what new research has come forth about stature increases or decreases in different countries? For example, are the Dutch still the tallest in the world? And do we see clear correlations between increasing stature and improved socioeconomic status? >> Well to start with the last question there are clear connections with especially the socioeconomic conditions of the people in the country. The better off they are, the taller they grow, not in one go, but through generations. And we do not have that much data from other countries. We have from quite a few Western European countries, and from that it shows that since the Second World War, the Dutch are the tallest. Before the second World War, this used to be the Scandinavian countries, but they, from 1980 got stuck at just under 180 centimetres and we've gained up until 184. But I have to say that the last ten, 15 years we haven't been growing taller. So we seem to have with the possibilities we have at the moment socioeconomically that maybe also genetically. This seems to be the limit for the average. Of course there are people taller or smaller. This is just about the average. >> Very interesting. >> I can add to that to predict something about countries we know little about. That since in the 1970s we had a huge immigration in the Netherlands of people from North Africa who were far smaller than the average Dutch at that time. That their offspring is gaining stature in an enormous way and may catch up with the original Dutch population. That has shown from the data as well. >> Very interesting. Thank you very much for sharing your research with us today Professor Maat. In this module you've learned about stature estimation methods from skeleton. And you've seen an expert on osteoarcheological stature research, demonstrate how interesting and informative these types of studies are. You've no doubt learned a lot. In the online discussion forum there is one question in particular we would like you to answer. And that question is how tall are you really? What factors can come into play when you either measure your own height or it's done by another person such as a nurse or a doctor or the employee at a driver's licence office? Have you ever perhaps exaggerated your height a little bit? And did you know you really are a little bit taller in the morning than you are at the end of the day? This is true, check out the online forum to find out why. Coming up next, is a short discussion where we return to some of the big questions that we pose in the very first video. And we hope to see you soon.
