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Osteological analysis: age and sex

Osteological analysis: age and sex
So you said you could sex the cremations. How would you go about doing that? Absolutely. So when you’re trying to determine sex in an individual you look at two main features, including the skull and the pelvis. Now unfortunately, with cremation deposits and because of the high level of fragmentation you don’t always have those parts of the skeleton surviving. So you kind of have to pick and choose whatever is available and make the most of it. So predominantly in the skull you’re looking for specific sexually dimorphic features. And these are features that are specific to males and females. And they vary in terms of shape and size whether or not you’re a male or a female.
And one example that we have here, here is the mastoid process. And this is something that you can find just behind your ear. And the size of this is sexually dimorphic, as well as the shape. So the bigger it is and the longer it is, it’s more male. But the smaller it is and the thinner it is, or shorter it is, is female. So in this particular individual you can see it’s very prominent, very long, quite sharp. This is what we consider to be male. So it’s aspects like this that we’re looking out for. This is quite a rare example. It’s– well, it’s a very well-preserved example. You don’t always find things like this within a cremation deposit.
Another example comes from the pelvis, and the main thing that’s very sexually dimorphic is what’s known as the sciatic notch, the great sciatic notch here. And again, this is something with specific shape and size to males and females. The wider it is is female, and the narrower it is, and almost the deeper it is, that’s male. So you can just tell by the shape and the depth of it whether it’s male or female. So if, as you say, you need the right parts of the skull or the pelvis to be able to determine, how often can you work out the sex in a cremation? Is it– are you likely to have that information? Not always.
It very much depends on each individual cremation how much material is there. And even if you do have a lot of material left over, you might not necessarily have those features that you need. So you do need a very good eye and able to determine if you do have even a section of that specific feature or the whole of it or just a small fragment of it. And also it’s best– if you’re not 100% sure, maybe go with just unidentified sex rather than assigning it to male and female. So usually the categories we use are male, female, or unidentified. And if you’re not 100% sure, then it’s probably best to leave it as unidentified.
So what about working out the age of the individuals? How would you do that? So age assessment is actually a lot easier to do than sex assessment, just because there are more features in the skeleton that we can use for ageing. One of these things is bone fusion. So younger individuals, their bones are made up of several components, and as you get older, they fuse together. Another aspect is looking at difference in bone size. So an adult bone is considerably more robust and larger in size than a juvenile bone. Other aspects include dental eruption– so deciduous teeth versus adult teeth or mature teeth.
Other aspects include looking at the vertebral bodies and how obliterated they are, and finally aspects of pathology as well. So individuals who may have more degenerative pathologies in the skeleton will suggest that they are older in age. So how accurate can you get about people’s ages from that information? Well, sadly, we can’t age them as accurately as we would like. We can only really narrow down to an age bracket of quite a few decades. So what we tend to utilise especially in this project, we’ve aged from 0 to just before puberty, so less than 13 years of age, and then sort of adolescence, 13 to 18 years of age, and then 18 and over.
And then the final bracket we could probably age to is 40 years and over. Right and can we age any of these particular individuals that we have? Yeah, absolutely. So this individual here that we have at the end, as you can see from these vertebral bodies there’s actually quite a lot of osteophyte growth around the edge both on the superior and anterior surface. And this is what is known as osteophyte development, and it’s associated with osteoarthritis. And this will typically occur in someone who is elderly or older or more mature in years. So I would assign this individual to being 40 years and over.
So have you worked out the age and sex of the individual that we’re looking at then? Yeah, absolutely. So as you can see from this individual, all the bones are fully fused, OK? They’re quite large in size, suggesting that they were over 18 years of age or an adult. And also there are some skeletal features that are more suggestive of being male rather than female– slightly larger, slightly more robust. So we would identify this individual as an adult male.

Carolina joins Emily again to find out what particular bone fragments can tell us about the biological sex and age of the individual.

(We use the term ‘biological sex’ or ‘osteological sex’ because the remains can only tell us about the skeletal features typical of males and females, and not the expressed gender of the person.)

diagram showing the Greater Sciatic Notch and the differences between a typical male and female pelvis including wider hips, sacrum, pelvic brim and subpubic angle in females

The differences between male and female pelvises. © OpenStax College, CC BY 3.0, via Wikimedia Commons. (Adapted by the course creators with the addition of the label ‘Greater Sciatic Notch’). Click to expand.

The bone fragment Emily discusses in the video has been identified as being from a female pelvis. Osteologists use a five point scoring system to assess the shape of an individual’s sciatic notch (Buikstra and Ubelaker 1994). A score of 1 is considered a definite female, and 5 is a definite male.

photo of the sciatic notch from the video with diagrams showing the wide (female - 1) or narrow (male - 5) shape.

Diagram showing the shapes that would score 1 and 5 which define ‘female’ and ‘male’ sciatic notches.

Emily also mentions ‘vertebral obliteration’ which refers to the degeneration of the vertebrae leading to changes in the shape of the spine, blocked blood vessels, nerve damage and loss of flexibility.

It’s much harder to identify the biological/osteological sex and age in cremated remains than it is with inhumations (the practice of burying the dead). Take a look at the videos in the downloads section if you’re interested in learning how age and sex is identified in inhumated remains.

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