#kyidylbones

Ethics: Beyond the normal respectful approach, there aren’t separate ethical considerations with dealing with age like there are for sex and race.  Just be considerate of the fact that child death is super upsetting to some people.  I literally had people in my classes at the masters level who were moved to tears by some of the younger remains, so even when you’re used to looking at things from a clinical perspective, kids can be tough.  

General: Age is separated into three general categories: juvenile (0-early 20s), adult, and elderly.  Juveniles are from birth until the last known skeletal change takes place.  IE, until all your teeth come in and all your bones fuse.  These are really good indicators of age, so we use them as much as we can for as long into the lifespan as we can.  Adults range from “done growing” to “showing signs of degeneration” EG, arthritis and that kind of thing.  Elderly is anything older than that.  

Also, this applies to all age categories: size is not an indicator of age.  Ever.  

Juveniles: We say juveniles instead of children because people in their late teens and early 20s aren’t really children, but they haven’t finished growing yet.  So juvenile is a more inclusive term, and the more accurate one.  That said, kids are by FAR the easiest to know the age of.  Juvenile remains do not look like small adult remains, because juveniles that have skeletons that do not resemble adult skeletons beyond the basic “ah, that’s probably a human”.  

There are a few ways that we determine the age of a juvenile, and the first thing we check is the teeth.  Before the body, before any other signs.  Because the teeth are consistently accurate across race, sex, economic standing, any pathologies, etc.  Teeth are formed and come in on a schedule.  Here is that schedule: 

And here is a link to a high res PDF version that you absolutely should take a look at (Source).  

Beyond this, the 3rd molar AKA wisdom teeth come in between ages 17-25.  Now, archaeological remains won’t have scars on the bone from the wisdom teeth removal that a lot of people commonly undergo, but in the future that will be visible on the bone.  I’ll get into this more when I get around to doing the damage and pathology posts, but healed bone has a different appearance than unbroken bone, so a healed-over tooth socket has a different appearance than bone that never had a tooth there to begin with.  In addition, while tooth eruption in a living juvenile is accepted as the time when the tooth breaks through the gums, in the remains of a juvenile we can see un-erupted teeth within the jaw.  It looks like this: 

(Source) 

As an aside: those lines on the teeth are called enamel hypoplasia, and I’ll cover it more in the teeth post, but essentially if you don’t get proper nutrition as a child when your adult teeth are developing in your jaw you get these lines in them.  

So anyway, because teeth come in on such a precise schedule, and because teeth survive better than anything else in your body (especially in a child’s body.  Childrens’ bones are fragile, partially ossified, and they decay quickly.), they’re very good for estimating age at death.  Even more so than bones, because bones can be altered by illness, malnutrition, repetitive activity, or genetic anomalies.  Teeth almost never are.  Or, rather, their rate of growth isn’t.  

Another thing we look for when determining age at death is the fusion of the bones.  See, as you’re growing you have more bones.  Those get larger until they meet up with the bone they’re part of, and then they start to fuse.  These are called epiphysis (growth plates).  Very young children don’t even have entirely ossified (bone instead of cartilage) bones, let along epiphysis that touch.  Babies don’t show up often in the archaeological record because of this. To better illustrate this, here is an image of an xray of a baby’s hand: 

(Source) 

You’ll notice that the finger bones (Metacarpals and carpels, known collectively as phalanges.) have small little bones at the ends that aren’t attached - that’s not an anomaly, that’s normal.  Those are the physis, which will fuse later in life after they are larger, and the plate between them from which they grow is the epiphysis.  You can also see that the wrist bones have barely begun to ossify and don’t show up on the xray, and the physis for the radius and ulna (arm bones) also haven’t begin to ossify and thus don’t show up - that’s why the arm bones look like one bone.  They aren’t, they have an epiphysis at either end (Your elbow is a separate bone called the olecranon and it doesn’t fuse until later on.).  This happens at a very predictable rate, and so we can tell how old someone is from a combination of their teeth and which bones have and have not ossified and fused.  In addition, the bone of the epiphysis has a unique texture that is referred to as “billowy” in the literature (even tho I hate that word).  Here’s a picture: 

(Source)

The one on the left is what you want to look at, since this is a progression through age.  Also I sniped this from a paper on age estimation, so if you’re interested in this take a look at it.  It’s on researchgate so it’s not behind a paywall.  As an aside: researchgate is amazing and you should all learn to use it.  

Anyway, see that bumpy texture on the left? That’s what unfused bone looks like at the growth plate.  This actually applies to, as far as I know, all land mammals.  So if you find animal bones with this texture at the end of the bone, then that animal was a juvenile when it died.  Bones fuse at different times in your life, but we know the times when they fuse.  There are 206 bones in the adult body, so that would be a lot for me to try and put in a tumblr post, but if you google a specific bone you should be able to find the ages they fuse.  I believe, if memory serves, that the skull sutures are the last to fully fuse, and they in fact continue to become more tightly fused as your life goes on. I’ll cover that in the next section tho.  It will hold together as a teenager, but the skull bones take a long time to fuse to each other.  Two of the last epiphysis to fuse though are the iliac crest (The curved part of the hip - it’s actually its own separate bone.  Like just the small, smooth curved part.) and the sternal end of the clavicle (clavicle = collarbone, and the sternal end is the medial part towards the sternum.).  This happens in your early to mid 20s.  

So teeth and bone fusion are the two most used methods of age estimation.  So if anyone ever shows you a small skeleton with fused bones and calls it a child, roll your eyes at them.  It’s not a child.  

One last note on juvenile skeletons: until the individual undergoes puberty, sex and race determinations are extremely difficult (teeth can be used for race, but not for sex.  Not really, anyway.).  So again, anyone who professes to know the sex of a set of pre-pubescent remains without like...a gravestone or something telling them is probably a liar.  Right now the methods for doing that are either expensive (genetics) or inaccurate.  And doing genetic evaluations on old juvenile remains is difficult, because their bones are more fragile than adult bones and break down easier, which exposes the DNA to easy degradation.  It’s not impossible, it’s just usually more difficult and more expensive.  

For reference, here is a juvenile skeleton laid out in standard anatomical position.  There is more than one individual here, so ignore any of the bones outside the arms and above the head.  

(Source)

Adults and the Elderly: After an individual finishes growing, estimating their age becomes increasingly difficult.  There’s no such thing as, for example, an average number of tooth cavities.  In addition, the natural growth and destruction of your bone cells over your lifetime means that things you do habitually can significantly alter the shape of your bones and the rate at which they break down.  

However, there are a few things that can be used.  Joints wear down at a fairly consistent rate, and arthritis leaves specific markers on the bones that we can identify as arthritis rather than normal wear and tear.  This is most easily views in two places: the public symphasis (the front where your two hip bones meet.) and the acetabulum (The socket that the round end of your thigh bone is in.).  The picture I used above is an image of the wear and tear seen on a series of pubic symphysises (symphysii? IDK.).  And so these are matched against skeletons whose age at death was known and age ranges for changes to this area were arrived at.  

When I was doing my MSc, we did a project where we were assigned a set of remains and had to use everything we’d learned in the course to do a full evaluation of our skeletons.  Well, the majority of my skull was missing and so I used the acetabulum to do age estimation on the skeleton (I had some teeth, but not most of the ones that are diagnostic of age, which I’ll cover in a sec.).  This is an image from and a link to one of the papers I used: 

(Source)

Two things happen here as you age.  One, the edges of the socket become damaged and it starts to change the anatomy (F is oldest).  Two, that space in the middle is called the acetabular fossa, or the acetabular notch.  And as you can see, the shape of it changes over time due to normal wear and tear.  In combination with resources like the one I linked, we can use this to estimate the age of an adult or elderly individual.  

Another tool we use has to do with the fusion of your growth plates.  After the bones fuse, the line is still visible.  Throughout your life the remodeling (normal breakdown/growth of bones and healing from damage.) causes the sutures to be come less and less visible.  We call this obliteration.  In the elderly, most of their sutures and growth plates will be completely obliterated.  For example, the femur is in four pieces as a child.  The main body of the femur, the head of the femur, the greater trochanter (The big bump on the top outside.  This is like...the part that’s wides below your hips where your thigh meets your pelvis, but on the outside.), and the condyles (the rounded pieces on the far end.).  The greater trochanter fuses and obliterates pretty early on, but the head and the condyles are pretty easy to see even in adults.  Here’s an example showing the femoral head: 

(Source)

As you can see, the trochanter has fused and is obliterated, but the head has fused and you can still see the line from the growth plate.  The sutures in the skull are especially good for this, as cranial sutures take the majority of the lifespan to obliterate (sometimes they never fully do.).  If you see a smooth skull, that person was ooooold.  

The last easily accessible way we assess age at death is via tooth wear.  Now, this won’t work in modern skeletons, which is why there’s a lot of research surrounding the evaluation of age at death.  We’re well aware that after humans entered roughly the industrial age, our foods became soft and teeth no longer wear like they should, and after that point in time it’s not possible to use the standardized methods of tooth wear to evaluate age.  Well, I should rephrase, it won’t be possible in westernized and industrialized societies.  Cultures in Africa and South America that still practice pastoral or hunter/gatherer lifestyles will likely still have expected tooth wear.  Anyone who lives in a society that has and uses grocery stores or doesn’t use two rocks to mill flour (Do not underestimate how much bread people ate.), is not going to have expected tooth wear (so it’s not about rural vs city.).  

See, it’s normal and natural for teeth to wear.  It’s normal and natural for the yellowish substance below the enamel, called dentin, to show.  Dentin is almost as hard as enamel, and it actually regrows.  We evolved to have tooth wear both on the surfaces and between the teeth.  Humans used to eat much tougher foods, and even when we weren’t, our foods had a lot of grit in them (IE, tiny pieces of stone from milling flour.  I have a whole ass theory about the role of dirt in the evolution of teeth for all animals but that’s neither here nor there.) and wore our teeth down.  Wear isn’t a sign of bad dental hygiene, it’s a sign of a tougher diet.  After the industrial age we started using different methods to produce food and started eating softer food overall, so we stopped putting the stresses on our jaws required for both proper tooth wear and the proper growth of our teeth (AKA: wisdom tooth impaction.).  So normally worn teeth look like this: 

(Source for both images)

If you’ll notice in that top image the lines where the teeth meet fit exactly together.  This is because of tooth wear.  Interestingly you’ll also notice in the bottom image that this individual’s teeth are unevenly worn, meaning they chewed on the right side of their mouth.  This is actually something we see all the time because of both handedness, and insult to the teeth on one side of the aw (AKA it was painful cause they had cavities.).  This individual was likely a young adult given that they don’t have a lot of tooth wear to begin with, but they were preferentially using one side of their mouth to chew and so it is more worn than it would be for someone who wasn’t doing that.  Here is the chart we use to grade tooth wear and age on adult teeth: 

(Source)

That link has a larger version of the chart and more images.  

So the fact that I’m 40 and still can feel all the cusps on all of my molars is an anomaly compared to previous humans.  Soft foods.  So if you compare the above image of the jaw with the chart, you’ll see that the individuals in both pictures have wear in the 25-35yrs old age rage, or what we would consider to be a young adult.  And before you start talking about average age of humans back in the day, don’t forget that the average includes a lot of dead children.  Once you made it to adulthood you lived a decent amount of time.  

So those of you who are older than your 30s or so might not remember this, but when your adult incisors come in they had small ridges on the edges.  It was easier to tell on your top teeth (maxillary incisors) than your bottom ones (mandibular incisors.), but it’s present on both.  These bad boys: 

(Source)

That is obviously a living human, but I’m showing you because they wear quickly.  They do, however, wear at a prescribed pace so if a set of remains has them they were young.  Sometimes they’re gone before you’re even an adult, but I figured I’d mention them because they are another kind of tooth wear.  

Disease: The last thing that helps in age determination are age-based diseases.  Namely, osteoarthritis and osteoporosis.  There are circumstances wherein someone younger can have both of those pathologies, but that’s why we have all of the other things.  So if we see signs of arthritis in a younger person, we’ll have the other signs to help us realize that they aren’t an elderly individual.  

Osteoarthritis is, essentially, a thinning of the cartilage, fluid, and other soft tissues in the joints, causing the bones to rub against each other instead of sliding nicely on the cartilage.  Now, a certain amount of thinning is expected with age - obviously, as arthritis in the elderly is extremely common even now.  But osteoarthritis is an escalation of the normal wear and tear into a pathology.  Osteoarthritis damages the joints, and so bone attempts to regrow, so you see a lot of abnormal outgrowths of bone that fit tightly together because they were rubbing against each other.  You also see, in extreme cases, striations on the bones where they were grinding together.  Like this: 

(Source)

This is a knee joint, viewed from the posterior side.  You can see on the bottom condyle and the opposing articular surface that there are lines.  Those lines are from the bones grinding.  You also can see, especially on the tibia, all those little funky looking bone bits.  All that roughness sticking out around end, below the flat surface.  Some roughness there is normal, but that’s rougher than it should be and that’s the result of osteoarthritis.  

The other disease common in the elderly is osteoporosis.  Osteoporosis is an illness that causes compact/cortical (the thicker hard bone around the spingy bone to thin and become porous (hence the name.).  I’ve held bone with extremely advanced osteoporosis and they are about half the weight of normal bones.  So that’s the first sign.  The next sign is that they’ll be damaged, both from the natural processes of time and from subsequent handling, because they’re farm more fragile than health adult bone.  The vertebra also take on a “squished” appearance due to the forces of gravity and the remodeling during the life of the individual.  You also will often see poorly healed breaks (I’ll show you more of this later in this series when I get to pathologies.).  

The pelvis of an adult human is a really common thing for an archaeologist to find.  And by the time we find it, it’s usually in three pieces (excluding your tailbone aka last vertebra).  Your left and right hip bones, called the innominates, and your sacrum.  Mind you, the pelvis is made up of a number of bones, but they all fuse in adulthood except these three (fun fact: I’m so used to using the individual names for them that I had to *google* the word innominate.), so this is what we usually find.  If it’s a kid, they still survive well because they’re thick, heavy bones, but they aren’t fused.  Another fun fact, the bumps of bone that you feel under your ass are called your ischium and I’m only telling you that because I think it’s a fun word to say.  Your hop bones, like the actual entirety of the flat bladed part at the top, that’s called the Illium.  I like that word too.  Aaanyway, here’s a human pelvis: 

(Source)

These are actual bone specimens in the top down view, both are women, but they are of different ethnic origin.  

(Source)

This is a cast (IE, plastic), front view of a male pelvis.  

You can see those 3 pieces I’m talking about.  The only joint there that remains unfused is the sacroiliac joint, IE, where the two halves of the pelvis join the sacrum.  However! You sacrum is technically a series of fused vertebrae and your spinal cord runs almost all the way to the very tip.  There are some conditions which cause these not to fuse, or to not fuse properly, or to not properly encase the spinal cord and it causes all KINDS of issues.  But anyway, yeah, your sacrum is a really tough hunk of bone because it carries a lot of weight.  The bit in the front is called the pubic symphysis and, despite what certain tumblr posts would have you believe, having children does NOT leave a notch on the inner side of it from the muscle tearing away tiny chunks of the bone.  In fact, it is hotly debated whether or not pregnancy leaves behind any skeletal evidence at all.  

Alright, so basically speaking, females make da babies and males don’t, so the different equipment is differently shaped......

.....wait, no, that’s not right.  Let’s back up.  Male and female humans are differently proportioned and their center of gravity is, on average, different.  This is the whole thing about men having upper body strength and women having thighs that can crush watermelons.  This is on *average* (I will be saying a lot about averages in these posts.) true.  And so the physics of the forces exerted on your bones is different.  Males are top-heavy, and so their pelvis is shaped in response to their gate and muscle structure because the pelvis supports and distributes the weight of your entire body.  And bipedalism means that the shape of the pelvis is very, very different depending on the weight distribution.  These changes to the pelvis are really obvious, which is why we can tell from just a few bones whether or not a hominin was bipedal.  It changes the *entire* body.  

It is true though that the pelvis of a female is different than a male, because a female pelvis has to be able to support the weight of a developing child while still allowing the individual to walk.  So the interaction of average size, a uterus, and the bipedal gate means that male and female pelvises are a different shape.  

Here is a comparison: 

(Source)

So firstly, that angle is called the sub-public angle, and because a females pelvis is wider and flatter than a male’s (when viewed from the front) it’s wider in the front.  This also gives any babies more room.  Secondly, you can see the difference in the tilt of the sacrum - in the female you can’t see the tailbone.  This, again, is due to the confluence of weight distribution and the necessity of passing a baby’s head through that space.  It would be a lot harder to push it out if you had a tailbone in the way.  Lastly, you can see that the shape of the circle when you look top down and bottom up are different - wider on the woman because of the same reasons I’ve already mentioned.  There is one more major difference between the male and female pelvis, and that’s the sciatic notch: 

(Source)

Characteristic of male on the left, intermediate in the middle, and female on the right (and dang, she was young, too.).  Thinner is male, wider is female.  Usually you can fit your thumb in a female’s notch but barely or not at all in a male.  I personally find the subpubic arch and the sciatic notch the easiest to use because, fun fact #2, those 3 sections are a bitch to hold together with your hands and that makes it hard to see the other shapes.  The amount of sacrums and pelvic bones I’ve accidentally dropped while trying to determine sex....it’s a lot, ok? It’s a lot.  I only have two hands and pelvises are big.  

There are also several less obvious ways of determining sex from a skeleton, so you guys should definitely visit the source for the above image because they go into it deeper and there are several excellent images of public bones.  

So how else do we determine sex? The next easiest way is from the skull, because the features are distinct and skulls survive well.  

The Skull

In my opinion the easiest landmark to use on a skull for sex determination is the jaw.  There are several features of the jaw that can be used here - and, mind you, when determining sex we measure every small and large sex-linked feature according to a scale and then average it all out.  We never look at any single thing (although sometimes the individual has something so characteristic that you can’t help it.  The individual in my position has a brow like a neanderthal, so it was pretty obvious.).  Anyway, there are several features here but the easiest is to look at the shape of the lateral distal posterior portion of the jaw.  It’s called the masseteric tuberosity.  Basically, it’s a little bit of bone that sticks out of the back of your jaw.  It’s one of the attachment points of the masseter aka chewing muscles attach.  Because males have stronger muscles pulling on that part of the jaw and exerting more force, it flares out further for them when you look at it from the front, like this: 

(Source)

It’s that sticky-outy thing thing that I circled in red.  Here is an example of the same thing on females: 

(Source)

Female jaws are rounder, and so that bit is less defined, flares out less, and is not as sharp as it is on males.  And this is a reminder that these measures aren’t absolutes - humans have a lot of variance in them.  The female asian and the male on the right both have somewhat atypical structures, while the female european and the two other males have a very characteristic structure.  

The two other easiest to identify are the shape of the brown line and the shape of the chin (the mental protuberance).  Here is an image of the comparison: 

(Source: Pinterest, but this images are from the Human Bone Manual text that I use and I used this image so I wouldn’t have to make my own. :P) 

You can see in the profile that the female skull has a higher, more vertical forehead with less pronounced brow ridges.  If you look, you can also see that her chin protrudes less in profile, and is softer and less pronounced in the frontal view.  The angle under her teeth is less severe.  

So these three things, the chin, the brow, and the jaw, are the easiest to identify the most likely to be characteristic of the sex of the individual.  But, if you compare the images I’ve used here you’ll also notice that there are other differences in the skull.  Females have more of a slope to the bottom of their jaw, the bump on the back of their heads (the occipital protuberance) tends to be far less pronounced; and this is the case for all muscle attachments generally speaking.  On average, males are more easily able to build muscle mass and are larger, and so their muscles pull harder on their skeletons and create larger muscle attachments.  The round, blunt thing to the right of the back of the jaw that sticks out from the skull (the mastoid process), is also at a different angle and is larger in males.  This is another case of the muscles being bigger and stronger - the mastoid process is where several of your jaw and neck muscles attach.  

There you have it, then.  The easiest ways to tell the sex of a skeleton.  :) 

This post has been approved by Gage the science doggo: 

White/Caucasoid.  

Female, front view. (Source)

Male, profile view (Source)

So let’s break this down in an orderly way (I will put the comparisons and stuff at the bottom in an orderly table for easy reference.  Hell, this is partially for my own reference too bc I never remember this stuff off the top of my head.): 

Eye shape and sharpness - This is easiest to see in the front view, obviously.  White skulls that have stereotypically white features will have eye orbits that are technically called “square with rounded edges” (or as we call them in the nail world....sqoval.), but they sit at kind of an angle where they’re higher in the middle and lower at the lateral sides so most of us just refer to them as “aviator glasses” which I think is pretty funny of us.  And although you obviously can’t feel it with your fingers, the borders of the eye sockets will be sharper.  

Prognathism - As you can see from the bottom image, on a caucasian skull there is a low amount of prognathism.  The chin is often behind the spine of the nose rather than protruding.  European skulls have flatter faces, basically.  Although this male has a bit of an overbite so the curve around his teeth is more severe than it otherwise might be.  Generally speaking though, you’ll be able to draw a line from the nasal spine to the chin and not much will stick out past the line and the line will be straight.  The “muzzle” area of the face is less pronounced.  

Nasal Shape - This is actually mathematically determined by a measurement called the nasal index.  It is the ratio of the height to the width multiplied by 100.  European skulls have thin, tall noses, and you can see that illustrated pretty well in the woman above.  

Nasal Sill - On caucasians, the nasal spine aka sticky-outy-bit at the bottom of the opening that you can see in profile is more pronounced.  It sticks out further.  This means that a caucasian skull will also have more guttering behind the edge of the sill.  IE, if you stick your finger in its nose and run it along the bottom of the nasal passage, you will feel a distinct dip. Europeans have a distinct nasal sill.  

Nasal Bridge - White have shorter nasal bones, and so the bridge of their nose is shorter in profile.  It also usually has a more extreme curve in the area inferior to the browbone.  This male actually isn’t a good example of that, because his nasal bones are long for a caucasian skull.  Basically, our noses stick out further.  

Unique skull features - None.  Caucasian skulls are kinda boring TBH.  

Next, we have black/African skulls.  In the US especially this can be a lot harder to determine because of centuries of admixture with the white population: 

This is a front and profile view of the same male, african individual. (Source)

Something you’ll start to notice as we go through this is that Black skulls and white skulls usually have opposite features and asian skulls are between these two extremes (Except for eye orbit shape.  Here it’s Asian on one end and African on the other, with European inbetween.).  If you think about geography here, it kinda makes sense.  Anyway, the skull features: 

Eye orbit shape and sharpness - African skulls tend to have eye orbits that are more square in shape, and often aren’t angled the way they are in whites.  This individual’s are angled though so they’re not super stereotypical of what would be considered characteristic of African eye orbits.  His are fairly square though.  The edges of the orbits tend to be softer and less distinct.  

Prognathism - African skulls are prognathic, meaning that they stick out the furthest.  In this individual, you’ll notice that it isn’t just his teeth that stick out past the line because of an overbite, the entire upper part of the maxilla is curved outwards.  African faces are much less flat than white ones.  The “muzzle” area is more pronounced.  

Nasal Shape - As you might expect, African nasal shapes are much wider and shorter than European ones.  They appear a lot rounder, and this is something that’s fairly unique to them, especially if the individual has very stereotypically African features.  

Nasal Sill - The nasal spine sticks out much less in an African skull - I’ve seen individuals who barely had one at all.  Between that and the prognathism, the bone almost seems as if it stretches, and you see very little silling.  So if you stick your finger up its nose you won’t have a sharp edge with a dip behind it in the nasal passage.  Sometimes there won’t even be a sill at all.  I actually found a really good image of this, but I don’t want to mess up tumblr’s list ordering, so I’ll stick it in below the list.  

Nasal Bridge - Africans have flatter noses, and to accommodate this their nasal bones are longer and the curve that’s inferior to the browbones is much less acute.  Their noses stick out less than that of Europeans’, and it’s something that is fairly consistent in their skeletal remains.  

Unique racial features - Not many, but Africans do have something called a “bushman’s canine”. Now, I’m gonna be honest with you guys and tell you that I STILL have problems identifying this feature.  This is despite the fact that I was taught dental anthropology by one of the dudes who basically came up with these guidelines.  So on the bottom of the upper canines there is a bump of tooth enamel that is more pronounced on Africans than it is on other races.  There’s a grading scale and stuff.  You can read about it here.  Now I found that by just googling Bushman’s canine, but one of the authors (Joel Irish) was my prof, lol.  Here’s a picture of it, but actually the drawing in that paper above is better at illustrating the two opposite ends of the scale.  I added the lines: 

(Source)

In addition, here’s the image showing the nose shape: 

(Source)

African skulls will also sometimes have stronger muscle attachment sites, but honestly there’s a lot of that part of anatomy that’s social so it’s not something you can use to ID them unless you know what they should be for the society you’re looking into.  

Ok, so that’s African skulls done.  Next up, Asian.  As a reminder, Asian and Native American skulls are *extremely* similar.  This is because they share common ancestors.  This is also confirmed by their genetics (Native American genetics are super interesting, but that’s a whole other thing.).  

(Source)

This is an Asian male.  

Eye Shape/Sharpness - Asians and Natives have round eye sockets, and the edge of the socket is of middling sharpness.  In addition, their cheekbones tend to be flatter and wider, so the combination of these things makes their skull shape pretty distinctive.  Personally I find Asian and Native American skulls to be the easiest to ID, and a lot of these features persist through admixture, too.  

Prognathism - Asian/NA skulls have a middling amount of protrusion.  This individual has a distinct prognathism, but it’s honestly hit or miss.  They can have it either way.  Asian cheekbones tend to mitigate the visual effect though so it’s a bit harder to see without specifically looking for it in profile with a straightedge.  

Nasal Shape - As you can see from this individual, the nasal opening is neither as tall as caucasians nor as wide as Africans.  Again, this correlates to what you might expect given their phenotypes in life.  Theirs are the most heart shaped, too.  

Nasal Sill - This is another area where they fall between the “very pronounced” of whites and the “not at all pronounced” of Africans.  This individual barely has a nasal spine at all, but does appear to have something of a sill that would be present if you felt inside the nasal passage for it.  

Nasal Bridge - Same as above, it falls in between the two extremes in shape and length.  

Unique Racial Features - This is why I think Asian and Native Skulls are the easiest to ID.  They have some really interesting racial quirks i their skull anatomy.  First off, they have what’s called a persistent metopic suture.  When we’re all babies our forehead (frontal) bone is in two pieces, and then they fuse.  The suture between the two is then obliterated, IE, completely healed and smoothed over.  In Asians and Native Americans, this suture fuses but you can still see it: 

(Source)

It’s a completely harmless genetic variant that runs in those racial groups.  The second easy to identify feature is shoveling.  On the back of the upper (Maxillary) incisors.  It’s basically just a difference in shape; a border around the back of the tooth.  It looks like this: 

(Source)

And here is the scale we use to grade it: 

(Source - heheh there’s Joel again.)

It’s found on the lower incisors as well, but it’s easiest to see on the maxillary ones.  

The last easy indicator is found along the sutures along the top and back of the skull.  The coronal (arc along the front like a crown), sagittal (top center) and lambdoid (where the parietals fuse to the occipital.  It’s like a downward V on the back of your skull.) sutures can be what’s called simple or complex.  In Africans and whites, the sutures are mostly simple.  In Asians and Native Americans, it’s complex.  What that means is that the wiggly line is so wiggly that it loops back on itself and forms extra small bones called wormian bones.  Sometimes these bones can actually be very large and have names.  Here’s what a skull with small wormian bones looks like: 

(Source)

The bones with the star are the wormian bones, although there are other, smaller ones.  Very large ones are called Inca Bones, after the population they were first identified in.  They look like this: 

(Source)

A and B are examples of Inca bones.  They’re generally a harmless genetic variant.  

Lastly, we’ll address aborigonal features: 

(Source)

This is an aboriginal man.  Aboriginal is a generalized term for any indigenous group, but in anthropology - and from what I can see most places - we use it to describe people indigenous to Australia and the surrounding islands.  The reason why it is only sometimes considered a separate category is that it’s pretty localized, and the differences really come down to some special features.  So here are the main differences you can look for to tell if a skull is aboriginal: 

Large teeth.  Aboriginal people have really big teeth.  There’s no other way to put this, they just...they’re large.  

Very pronounced browbone.  As you can see above, the browbone is MUCH heavier on an aboriginal skull than on any other kind of skull.  This is especially true for males.  

Flatter chin.  It’s called the mental protuberance, and on an aboriginal individual it is less prominent than on other individuals.  

Large occipital bun.  The occipital bun is the bit at the bottom back of your skull where your neck muscles attach.  You can see it in the profile picture in the far right sticking out of the bottom of the skull.  It’s especially pronounced in aboriginal people.  

Ok, so there is one more important characteristic for judging race that I totally forgot to include yesterday, and that’s palatine shape.  The dental arcade is the area of the maxilla that houses the teeth.  Basically the top of your mouth.  And as you, a human person, knows - it’s in the shape of an arch.  But that arch varies in shape from race to race.  And, what your probably don’t know from not seeing a bunch of skulls, is that there are sutures in there.  Between 2-4, but even when you have two they bisect each other and look like 4.  The shape of these sutures also varies from race to race.  Again, it’s a harmless genetic variant that runs in various geographic areas.  However, I’m going to elect to skip it because there’s already a LOT of info in this post and going into it with the depth it deserves would be a lot.  Instead, I’m going to just summarize here for you all WRT the characteristics I’ve listed: 

Eye sockets: White - Aviator glasses, rounded square, sharp edge.  Black - square/rectangle, blunt edge.  Asian & Native - Round, middling sharp edges.  

Prognathism: White - little to no prognathism.  Black - most pronounced prognathism.  Asian & Native - varies between these two extremes.  

Nasal Shape: White - tall and thin.  Black - short and round.  Asian & Native - in-between these two.  

Nasal Sill: White - sharp nasal spine, deep well behind a sharp wall.  Black - Little or no spine, smooth sill.  Asian & Native - Varies between these two.  

Nasal Bridge: White - short nasal bones, more extreme curve.  Black - longer, flatter nasals, a much less extreme curve.  Asian & Native - you guessed it...between these two extremes.  

Unique racial features: White - None. Black - Bushman’s canine.  Asian & Native - tooth shoveling, persistent metopic suture, wormian/Inca bones.  

Here is an image of mixed animal bone from my own collection: 

Ooooo so many cool things in this one picture.  There’s burned bone, small bone, big bone, MgO staining, teef!, moar different burned bone...and one of the things that gets mistaken as human most often: turtle shell.  It’s the piece that’s in the top row, fourth from the right.  It looks very much like human skull when it’s fragmentary and is easy to mistake it as such.  It’s flat and the lines look like sutures (place where the bones in the skull fused, and are now the markers of separate bones.), but they don’t go all the way through.  Anyway, this is a good depiction of the wide variety of colors animal bone comes in.  The large piece in the very lower right is close to what I’d consider an average.  

Here’s an image of human femur that has been defleshed, but not buried: 

(Source)

Probably a young adult because the bone is in good condition, and the head has been fused but the suture isn’t completely grown over (obliterated).  

These are also human femurs: 

(Source)

Side note: they all probably had rickets and that center one is a juvenile, and I’ll teach you how to ID that later on.  They were found in a cave, a burial, and an archaeological site respectively.  

This is another femur: 

(Source)

Bottom is the femur, and it has a healed break in the middle.  The top is also a femur but it has....so...so...many problems.  SO MANY.  I could barely tell it’s a femur from this angle.  

Anyway, the color and texture on that front femur is what I would consider like an average color and texture for a human bone.  And it’s tan, sure, but it’s a different color tan than animal bone, especially IRL.  

In short: human bone looks different and feels different than animal bone, even before you take into consideration things like anatomy.  

Regarding anatomy, it’s...well, it’s an incredibly complex topic and I don’t know that I can really cover it appropriately here in my blog.  It mostly boils down to the impact that bipedalism has on our bodies, the impact that a big brain has on our skulls, and the impact that our manual dexterity on our fingers.  The walking thing is especially important because it changes *everything* about our anatomy.  Like...head to toe.  Everything.  

If you’re interested in human bone anatomy I have two resource recommendations for you.  First, The Human Bone Manual.  This is the one I used for school, and it’s the most useful textbook I’ve ever purchased.  I still use it all the time.  The ebook version is around $18.  Second, this app is called Essential Skeleton 4. It’s free, and it’s the most comprehensive skeletal anatomy app I’ve ever seen (and I’ve used a LOT of them.  It’s made by the same people who make essential anatomy - but EA isn’t free.).  Unfortunately, it’s iOS only and I’ve never found a decent alternative for android. :/ 

There is a lot more to telling human from animal, but my hope is that you’ll pick it up as I make the other entries into the series.  My best advice here is to develop an eye for detail.  Be like Elliot Spencer: it’s a very distinctive ___________. 

One final note on anatomy: people almost always do not realize what size bones actually are.  Human femurs are long and they’re heavy for their size.  They’re usually at least a foot or two in length (I mean...obviously...height is a factor.). The head is good and solid, and the shaft is thick with a lot of compact bone, but when the soft tissue is gone they’re hollow.  Most of the long bones are.  Foot bones are larger than most people expect. Skulls vary in size between softball-ish and volleyball-ish.  And human bone has a distinctive density which, unfortunately, you can’t learn the feel of without handling bone.  If you pick up a bone that looks right but doesn’t feel right - you know it.  I handled a human femur that felt like bird bone (bird bone is very light with a lot of spongy bone bc they fly.) because of a pathology (a non-standard but usually naturally occurring thing on the bone.  Breaks aren’t a pathology, but their regrowth can be.  Syphilis damage is a pathology because bacteria is naturally occurring, as are things like bone cancer, osteoporosis, etc.).  Other times it’s because your damned osteology prof mixed in a human-looking animal bone with the box of remains to trip you up because the differences can be real subtle and you need to learn that.  

How do you know where to dig? Sometimes, honestly....we don’t.  We’re just making educated guesses based on migration patterns and known settlements and research into local history.  Generally, if there’s a group of people who lived somewhere, they also did something with their dead.  So if you have a settlement, you’ll probably find bodies in it or near it at some point.  Sometimes people find remains and are like “uuuuuhhhhh....” and we come and dig ‘em up.  This is especially true on private property.  Farmers are notorious for this.  Construction, too, obviously.  Sometimes we look in caves, because very old caves have lots of dirt on the floors and a lot of times if it’s a good cave there’ll be bones in it.  Sometimes people threw their dead in bogs and now we have stuff that isn’t skeletons but is really old.  

(Source)

That is a whole ass human dude.  He’s around 2000 years old.  You can still see his facial hair.  

So there’s a lot of science behind how and why different environments preserve bodies differently, and I couldn’t possibly get into the detail of that here, but it’s definitely a factor we consider.  A swamp in Florida isn’t a good place to expect to find remains, you know? General rule of thumb is: more water = less body, unless there water isn’t standard water (it’s very alkaline, very acidic, or very frozen.).  Dry, cold landscapes like the Andes are great for preserving bodies.  

So what you find when you go looking is going to vary wildly depending on the environment.  My personal experience, though, is in graveyards.  Graveyards are an easy thing to dig because it’s not uncommon to just like...know where one was.  But graveyards aren’t the orderly things you’d expect them to be, not even modern graveyards.  People bury their loved ones on top of other people, graves intersect, and sometimes people would sneak bodies into the consecrated part of the graveyard when the priests/monks/etc. said they couldn’t be buried there.  So you can have bodies mixed with other bodies or under other bodies or just like random parts of people that were dug up, someone said “oops”, and then they were re-buried in a different spot.  So when we dig a graveyard, we keep complex records of where all of the remains were found, including in-depth drawings.  This is one way in which it’s similar to digging up a settlement.  It’s...pretty much the only way in which it’s similar.  Because part of the reason we do this is so we don’t mix up peoples’ body parts.  Graveyards aren’t what you expect - when I was digging in one we thought we’d gotten most of the bodies out so we were using a mattock to make sure and the site director missed cracking the skull of an intact child by about a centimeter.  Luckily the swing tore up a little bit of dirt and exposed it, but if it hadn’t? The next swing would have gone right through and inflicted heavy damage.  So you have to be careful even in a graveyard.  

Another thing about graves is that it doesn’t take long for the wood of a coffin to decay, so when you dig them up you will often just find the body and sometimes some nails.  The nails are good, because they show you the outline of where you can expect to find parts of the same individual.  This is one of the ways we show respect - we do everything in our power to NOT mix up the remains of different individuals and to separate them when we can.  

Let me sidebar here for a minute to explain.  See, your bones fit together.  I don’t meant “ah yes, everyone’s shin bone connects to their thigh bone”.  No, I mean that those bones have grown together in the same space for YEARS and they fit exactly.  They have the same texture and thickness, they go together like puzzle pieces....at the spots where the bones touch.  Or, as we say, articulate with each other.  See, if I were to take, say, my cuboid and try to trade it with someone else’s, it wouldn’t articulate right.  But something big like a tibia and femur will not be as easy to piece back together.  That, and we don’t always have complete bodies.  So we have something called “MNI” meaning “Minimum Number of Individuals”, and the maximum.  So...three left femurs mean at least three people.  Four right humeruses mean at least four people, so the minimum is 4.  However! We don’t know if any of those left femurs or right humeruses belonged to the same person because they don’t articulate with each other.  So the maximum is seven people.  We have between 4 and 7 people in that set of remains.  This becomes really important when you’re dealing with intersecting graves, mass graves, etc.  Any time the remains are what we call comingled (mixed).  This is what we’re really meticulous when recording where we found a given bone or set of bones.  

Ok, back to the main thing.  So...how DO we dig up dead people, anyway? It’s generally done in three stages: 

Exposing - This is where we dig down just enough to cleanly expose what we believe to be the margins of the grave.  We dig to the edges of the grave, not to a set square size like you would with a settlement. This is where we dig really cleanly, expose any grave goods, take pictures, etc.  And it looks like this: 

(Source.  Was super frustrating searching for this bc I have several of these pics on my phone of the graves we dug and can’t use them for privacy/ethical reasons.) 

Pedestaling/Cleaning - This is when we dig down around the skeleton and the grave goods, and then we start digging under the bones in preparation for the last stage.  This is time consuming, detailed work.  When I was doing this with the child we found, I used a mini trowel the size of my thumbnail and a dental pick.  It’s *especially* important with juveniles because their bones aren’t fused and those unfused pieces are *tiny*.  They literally look like clods of dirt.  Most archs - rightfully - can’t stomach the idea of throwing pieces of a human body into the spoil heap, so we’re as careful as we can be.  This part, when done right, takes days.  It’s a difficult thing to get a picture of, but this one is close: 

(Source)

The tags aren’t something I was taught needed to be done, but I can see why someone would.  They’re basically just grave goods and features of the grave.  They’ll be used to make a map of what’s what later on when the writeup is being done.  

Lifting - We never just pull a bone out of the ground because it damages them.  So we dig around them until they’re ready to come out on their own (and in the case of a large set of broken bones like you see above in that person’s skull, we’d just take the whole pile - dirt and all - for processing in the lab later.  And no, it’s not normal to have the skull glued back together.  We don’t glue remains together.).  If one piece comes out before the others, it is bagged and tagged.  We try not to have them come out separately, but it’s better to do that then to lose one.  When we’ve cleared all the dirt out, we “lift” the skeleton, IE, remove it from the grave.  If I included a pic of this it would just be an empty grave. :P 

We make sure to take all of the grave goods and any soil samples with us, all carefully labeled.  Fun fact about soil samples BTW.  The soil around the bones and especially in the abdominal cavity can retain molecular traces and bacterial from the flesh that tell us about their gut flora and diet or about any parasites they had (parasites were super common back in the day.).  It’s....really cool.  So a sometimes, if we suspect that there might be money for that kind of analysis, we’ll take soil samples of the gut region.  

We are...well, we’re very ritualistic about all of this.  It is, of course, for scientific rigour.  But part of it is that we’re systematically dismantling these peoples’ final resting places.  They had lives and loves and spiritual beliefs that we are disturbing.  This is sacred ground for so many cultures.  So it always feels a bit like we’re doing these things in a specific way to show respect to the resting dead.  That’s why in my 4 types of anthropologists post awhile back I said that archs are chaotic outside the pit but anal inside it. We want to learn from the dead, and it all feels a bit ritualistic if I’m being honest.  And there’s this juxtaposition of digging in the dirt, in the chaos of earth and time, in a very structured, clean, orderly way.  

I went back and forth on the most concise, easy to understand way of doing this and it took me a bit to figure it out, but I think it’s going to be like this: I’m going to tell you what we look for generally, and then give specific examples in each category as we go through race by race.  So, there are a lot of things that can indicate race in a skeleton, but I’m only going to cover the easiest to digest.  Understand though that there’s a lot of smaller indiciations.  Like with sex, these are graded on a scale in relationship to how stereotypical they are of a given feature.  And, unlike with sex, it’s much easier for the opinion and biases of the examiner to alter the results because a lot of these comes down to “what shape is this thing and which shape is it closest to”.  This is, of course, subjective.  The ones I’m going to cover are: 

Eye orbit shape and sharpness. 

Prognathism (the amount that the “muzzle” area of the face sticks out.  Eg., how flat is or isn’t a face?)

Nasal shape

Nasal sill (this is the bit that sticks out at the bottom of your septum, and the “floor” of your nose/top of your maxilla in your nose.

Nasal bridge

Unique racial features.  

First, I’m gonna use some screenies from my ipad to be very specific about the area of the skull I’m talking about here.  These all were taken by me in essential skeleton and edited.  

Eye orbit shape: 

I think this one is one of the more accessible things to understand without a skull in your hand.  If you think of the way that people look IRL, there are physical features that tend to be more common in various populations, and that translates to the skull (and in case you’re wondering: no, white is not treated as the baseline here, but you’ll see.).  Here it’s the shape of the eye socket.  

Eye socket sharpness: 

When you hold a skull in your hand, if you run your finger over the part of the eye socket between the lines (really, the whole edge, but the effect is more pronounced at the bottom and on the lateral edges), it’s sharper on some races than on others.  Again - this is a skeletal marker of physical features that you can see in a living person.  I’m not going to point this out in the example skulls because you won’t be able to see or feel it in the images, but it’s a pretty easy to understand way of adding another racial marker to your tools.  

Prognathism: 

So the easiest way to understand this is twofold.  First, how far does the chin stick out in relationship to the top of the nose? This shows how far the face protruded in life.  Here you can see the angle is 88 (although honestly i’ve never known anyone to measure this - I’m using it to illustrate the point.), and I only know that because the ruler tool I used to draw the lines told me so, lol.  The easiest way to see this is to look at the curve of the profile like I’ve illustrated with the green line.  

Nasal Shape: 

The shape of the nasal opening varies between racial groups.  We look at the height and width from the places I’ve illustrated above.  Sometimes we also look at the shape of the sort of upside down heart area I’ve outlined, because human variation means that you’ve gotta have a couple of ways of doing things.  

The Nasal Sill gets two images cause it has two parts: 

The top one has a landmark called the anterior nasal spine highlighted (honestly I think of it like the pointy nose thing).  The degree to which it sticks out  varies by race.  It is part of the maxilla, and together with the two portions of the maxilla that i’ve circled forms the nasal sill.  A lot of textbooks refer to the nasal sill as having a “height”.  I found this confusing and I found the pictures confusing too, so I’m gonna try a different tactic with you guys.  So first of all, you can feel some of these bones in your face.  Pinch the bottom of your septum where it meets your upper lip and wiggle it.  Feel how there’s a harder bit under the cartilage? That’s the pointy nose thing...er, nasal spine.  Now - and this is a little gross but it’s ok I won’t tell anyone - if you feel down into the bottom of your nasal passages you can feel where this blends into your maxilla.  The cartilage rises up and that forms your nasal passage.  On a dead person, that cartilage isn’t there.  So the hard bone that you feel there is all we have.  Well, the angle at which that slopes deeper into the nasal passage varies by race (because nose shape varies by race).  In some individuals, the anterior edge of that opening is sharp and lifted, forming a sort of dip in the area I’ve circled above.  This is the nasal gutter.  And if you google that, you will be hard-pressed to find anything that explains it with any clarity, especially because you don’t have a skull in your hand.  But it’s one of those things that’s useful to know because it can be really distinct and easy to see the differences in.  

The Nasal Bridge: 

Because the shape of the nose changes the bones all around it, another indicator is what I’ve shown here.  The angle of the curve of that red line, and the length of the blue line.  That’s basically the length of the nasal bones.  You can also tell with the shape of them, and the shape of the place where they connect to the frontal (the suture that connects them to the brow bone.), but I’m not going to cover that.  We have enough nose things.