by Sue Black
The nose, which forms the middle part of the face, is wedged between the orbits and the mouth. The cheeks also sit in this plane, to either side. The nose houses the upper part of the respiratory tract and warms and moistens the air drawn in through the nostrils. Cold, dry air is painful to inhale. Our noses also have an important job as the gatekeepers of the lungs, helping to prevent foreign objects from getting into the respiratory system by trapping them in the sticky mucus that covers the hairs, or vibrissae, within the nostrils. The snottery green product of successful air filtration is familiar to us all, and especially to the little children it so fascinates.
As air is drawn in through the nose it circulates over the turbinates, or conchal bones (hence the word “conk”), which are highly vascularized and act like the folded metal slats seen in wall-mounted radiators. Having this massive blood supply within a structure that sits proud of our faces seems like something of a design fault, given that the nose is likely both to bear the brunt of any direct hit to the face and to suffer substantial blood loss as a consequence. Skulls are frequently found with broken nasal bones and a markedly deviated septum, often the legacy of knocks received in contact sports such as rugby or boxing.
The nose is also there to trap smells and convey them to the brain so that we can recognize them. At the very top of the roof of the nose is a small square of specialized mucosa, about 3 cm2 in size, known as the olfactory epithelium. Incoming odours are dissolved in the mucus and olfactory nerve cells transmit the information through the cribriform plate, a sieve-like piece of the ethmoid bone, into the cranial cavity. From here the signal travels, via the olfactory cranial nerves, to the part of the deep cortex of the temporal lobe of the brain where the message is received.
It is the connections of the olfactory cortex to ancient areas of the brain such as the amygdala and the hippocampus that make some smells particularly evocative. I only need to catch a whiff of wood polish or turpentine to be transported back to my childhood days helping my father in his workshop. An impaired sense of smell is now considered to be an early warning of neurodegenerative disease and a factor in identifying those at risk of developing dementia. It also came to be recognized as a symptom of COVID-19.
Forensic science is very interested in the kinds of things that we may choose to stick up our noses. For example, the habit of line-snorting cocaine can be detected in both the hard and soft tissues of the nose and palate. The ischaemic, or vasoconstrictive, properties of the drug leave their mark on the tissue and can eventually lead to necrosis and even ultimate collapse of the nose. Usually it is the cartilage of the nasal septum that is most obviously affected but the damage can extend to the palate, making it difficult for the person affected to drink normally without expelling the liquid out through their nose.
Nasal washings can therefore prove to be extremely important to forensic investigations. Flushing the nasal cavities and collecting the fluid, so that pollen, spores or other debris can be retrieved, may provide vital information about the environment in which the deceased took their last breath. When we can identify pollen from a particular plant within the nasal cavities, this may well indicate that the deceased was killed in a different place from where their body was found.
This procedure can be quite fiddly, but between us, a fellow scientist, Patricia Wiltshire, and I devised a method that has proved effective. Pat, a forensic palynologist (a specialist in pollen, spores and other palynomorphs), was discussing with me one day how difficult it was for her to obtain nasal washings during postmortems, because it involved flushing saline up the nose and attempting to catch it before it disappeared down the pharynx. She had found it no easier to try to flush in the other direction, from the pharynx upwards, and she was still looking for a solution.
I was reminded that we had recently talked about how, during embalming, the Egyptians would remove the brain with a hooked wire inserted through the nose, and this gave me an idea. I suggested that, once the pathologist had removed the brain during the PM, thereby cutting the olfactory nerves, she could perhaps use the filtration properties of the cribriform plate of the ethmoid bone to get the wash down the nose from the brain cavity above. Apparently, this worked a treat and so a new method was born. Magical things happen at thresholds where two different worlds collide and one can offer a solution to a problem that has been vexing the other.
The nose and cheeks may provide clues to ancestry. The shape of the zygomatic bones of the cheeks can point to eastern origins, while the nose often helps us to differentiate between the high-bridged characteristics of some ancestral groups and the broad internasal dimensions of others. It is fascinating to sit on a train or on the London Underground noting the massive diversity in the shapes of the various components that make up human physiognomy and imagining the underlying skulls. You do get some funny looks, though, as it is customary for people not to look at each other on the Tube.
Facial piercings are also very common in the nasal area, around the bridge of the nose, into the cartilages at the side or through the septum. We also see them, to a lesser extent, around the cheeks, where dimple piercings, paired studs inserted into the high point of the cheek, seem to be a current trend.
It is in the lower part of the viscerocranium, the mouth and chin, that the greatest growth in the face can be seen as we mature and try to make space for all our grown-up teeth. The human is a diphyodont, which means that we have two sets of teeth: deciduous (baby or milk) teeth and permanent (adult) teeth. Of course, we are really triphyodonts, because, thanks to the skills of our dentists, our adult teeth are not necessarily permanent, at least not in the form they grew originally, and may be replaced by a third set of plastic or porcelain teeth.
It is, of course, a golden rule never to assume that any removable feature will necessarily end up with the person for whom it was originally intended. I remember, when I was working as a consultant in Glasgow in the 1990s, being present at the postmortem examination of the body of a tramp who had been found dead in the undergrowth of a local park. There were no suspicious circumstances surrounding his death: he was an elderly gentleman in poor health and, given that he had been discovered on a winter’s morning after a cold night when the temperature had dropped well below zero, he had probably succumbed to hypothermia. But the police had no idea who he was, and it fell to us to come up with some clues to his identity so that any family could be notified.
He sported a full set of upper dentures (no lower ones) and, on the horseshoe area of the plate, we found a scratched reference number that could be used to try to locate the laboratory that had made the dentures for him, and, from there, perhaps lead us to the name of their owner.
However, it became clear as the investigation proceeded that the dentures worn by this gentleman had not been constructed for his mouth. We did indeed trace the laboratory and the man whose name they had on record was still very much alive. He had lost his dentures many years before, and it transpired that they may have gone through at least three identifiable owners before reaching the deceased. We thought it a testament to the famous Glaswegian iron constitution that the chap for whom the dentures had originally been made, betraying not the slightest hint of distaste that they had been found in the mouth of a dead man, asked if he could have them back as they were the “maist comfy wallies I ever owned.”
Such potential mix-ups are perhaps not as rare as you might think. A nurse at my father’s care home told me a story about an impish old lady who would go round at night collecting all the false teeth from the bedsides of sleeping residents and tumble them all into a sink (to “give them a good wash”), with the result that the next morning staff faced the time-consuming task of trying to match dentures to mouths, not always entirely successfully.
Teeth are the only part of the human skeletal structure that are visible to the naked eye and this makes them of significant value for identification purposes. They are also particularly useful in determining age. Tracing the development of the face
of a child into adulthood is fascinating. Much of the growth is to do with making space for the maturing and emerging dentition, which is relatively painless and happens over a long period of time, but it can be clearly seen in photographic portraits of children taken once a year throughout their childhood. I did this with my own girls.
By two years of age the largely nondescript “baby” face is gone and toddlers will be recognizable as miniature versions of the people they will become. The twenty teeth that make up the full range of deciduous dentition have formed and erupted so their little faces have to be sufficiently mature to be able to accommodate them all. By six, the face has changed again, this time to accommodate the eruption of the first permanent molar at the back of each quadrant of the mouth. They will now have around twenty-four visible teeth, and there is a great deal more going on up in their gums that can’t be seen.
There is a horrible phase between six and eight, during which the tooth fairy is disposing of the deciduous teeth and the permanent front teeth are erupting, when a child’s mouth looks a bit like a robbed graveyard, with tombstones at all sorts of angles and stages of visibility. The face then transforms one more time, when the second molar erupts at around twelve, just ahead of puberty, before settling into its adult form around the age of fifteen.
The final teeth may be the ones that cause the most problems, especially if you already have a crowded palate. The wisdom teeth, so called because they do not appear until close to adulthood, by which time we are all supposed to have achieved some semblance of wisdom, must try to squeeze their way into a mouth in which all the other twenty-eight are already in place. Sometimes wisdom teeth do not form at all; sometimes they form but never erupt, and sometimes they choose to sprout at unacceptable angles and become the bully boys, pushing all our other teeth around. Their presence, then, can be variable, but when they are there, they offer the forensic anthropologist a clear indication of the maturity of the individual under examination.
All of the baby teeth erupt from the gum and fall out between the ages of six months and ten years. The permanent teeth start to push the baby ones out between six and seven and are all in the mouth by the time we are about fifteen. These well-defined stages of development make teeth incredibly important to estimation of age in the remains of a child.
The knowledge that teeth are shed in a relatively predictable pattern was put to good effect in 1833 as the government tried to establish fairer conditions for workers, specifically in the textile mills. The Factory Act stated that no child under the age of nine should be employed. Yet often their ages were a matter of guesswork, even for the children themselves, as in the UK there was no registration of births prior to 1837, and it did not become compulsory for almost another forty years. So age, and a child’s fitness or otherwise to work, was established by looking at their dental development.
It was also acknowledged that no child younger than seven should be convicted for a crime as they could not yet be considered responsible for their own actions. The criterion used to determine age here was the eruption of the first permanent molar. If this had not yet happened, the child was deemed to be under seven and therefore below the age of criminal responsibility.
Forensic dentists, or odontologists, who specialize in the structure and diseases of teeth, are still employed today to help the courts determine the age of a child. Sometimes a minor who comes before the court, as either a victim or an offender, may not have documentation that confirms their age. Much of the world does not issue birth certificates and migrants and refugees who have fled for their lives do not always have their papers with them. In child slavery cases, any identity papers are often removed from the child, to render them utterly reliant on their “owners.” To determine the age of these children, it is considered safer to look inside their mouths to assess their stage of dental development than it is to subject them to radiation with an X-ray, although nowadays, other options are available: their bones can be examined by imaging that uses non-ionizing radiation, including MRI scans.
Dentition can help forensic scientists to establish if, and for how long, a deceased newborn baby survived after birth. Birth is a fairly traumatic process, not only for Mum but for the baby, too. It disrupts the development of the teeth, resulting in a “neonatal line,” a band which is microscopically visible in the enamel and dentine of the teeth formed up in the jaws at birth, and which is thought to be caused by the physiological changes that occur during the event. Since it appears only on teeth that are actively developing when a baby is born, it enables us to distinguish between prenatal and postnatal enamel formation. The approximate length of time the child lived can be calculated by measuring how much postnatal enamel has formed after the disruption that created the neonatal line. For forensic purposes, the presence of a neonatal line is accepted as an indicator of a live birth. When it is absent, it is likely either that the child was stillborn or that it died immediately after birth.
Our teeth change colour over time and can take on different hues when they are exposed to certain substances, which may offer pointers to identity. Children given antibiotics such as penicillin may be more likely to develop brown stains on their teeth. It has been suggested that this can also occur if the mother has taken antibiotics when pregnant. By contrast, an excess of ingested fluoride will result in white patches caused by fluorosis, a hypomineralization of the enamel.
Adult teeth may be dark in colour because of poor dental hygiene or staining by coffee, red wine, tobacco or other substances. Reddish black teeth might well be an indication of someone who chews betel nuts. This activity is prevalent in Asian culture and enjoyed by over 600 million people. In fact, betel nuts are the fourth most commonly consumed psychoactive substance after tobacco, alcohol and caffeinated drinks.
Today’s dentistry attempts to counter these hazards by promoting the ideal of the same perfect Instagram smile for everybody: beautifully even teeth (or veneers) and bright white colouration. This is not very helpful to forensic dentistry, which relies on identifying the variations that occur naturally in our teeth as well as those resulting from dental intervention or restoration.
Following the Asian tsunami of 2004, forensic odontologists were able to confirm the identities of some of the deceased through matches to bleaching trays, fillings, root canals and bridges. The more dental work we have done, the easier it is for our teeth to be identified as ours, provided, of course, that our dental records are available for comparison. On the other hand, the more cosmetic interventions we opt for, such as having our teeth straightened by braces, the more uniform and less individualistic our smile becomes.
It is rather ironic that whereas during our lives we battle with tooth decay caused by what we eat and drink, after we die our teeth can prove to be extremely hardy. They can survive explosion and fire damage, shielded from such ravages by being encased within the mouth, and in many circumstances their longevity can outstrip that of our bones.
As a result, and because most people know a tooth when they see one, forensic anthropologists are often presented with isolated teeth. But recognizing a tooth is one thing; being able to determine whether or not it is human requires a level of understanding of the variability of dentition in a range of common animals. So more often than not, it is the molars of sheep, pigs, cows and horses that cross our desks. If it is a human tooth, is it one of the twenty we have as a child or the thirty-two we have as an adult? Is it an upper or lower tooth? Is it from the right or the left?
Teeth can tell us a lot about the life of the person or animal they belonged to from both a phylogenetic (or evolutionary) and an onto-genetic (individually developmental) perspective. We form the type of teeth we are going to need to manage our diet. Canines are essential equipment for carnivores but surplus to requirement for herbivores. Both need incisors and molars, but the molars are of a different type. The committed carnivore will have carnassial, or slicing, molars that act like scissors to snip off the pieces of meat it consumes, w
hile the herbivore has grinding molars. As humans are omnivores, and eat a bit of everything, we have incisors to nibble and pinch, canines to pierce and molars to grind.
Sometimes the teeth that find their way to scientists are human, but turn out to be from a historic burial. The lack of modern dental treatment is an important indicator here but so, too, is the level of wear, which is not consistent with modern diets. High levels of carious lesions and decay tend to suggest a contemporary diet heavy in sugars whereas molars from archaeological remains are often eroded down through the enamel and into the dentine because of the amount of grit in the diets of bygone days.
Often it is that third, artificial, set of teeth that can prove the most fascinating, particularly in the shape of examples yielded by historical remains of the variety and ingenuity of the dentistry of the past. When, in 1991, I was part of a team excavating the crypt of St Barnabas church in West Kensington, London, the graves of three well-to-do women provided an insight into the everyday impact on their lives of their dental problems and of the efforts of their nineteenth-century dentists to solve them.
Sarah Frances Maxfield, the wife of Captain William Maxfield, who served in the navy for the East India Company, and in 1832 became the MP for Great Grimsby on the south bank of the Humber estuary in Lincolnshire, was buried in the crypt in 1842. She had been laid to rest next to her husband, who had died some five years previously. Other than that, all we know of Sarah is what we could surmise from the skeletal and dental remains within her lead coffin. She was evidently a lady of comfortable means, able to afford not only a triple coffin (a multilayered affair of wood and lead typical of the period for the wealthy), but also some expensive dental work during her lifetime.
