by Sue Black
The human body responds in a variety of ways to the stresses placed on it, especially by repetitive activities, and bone can retain discernible echoes of an occupation undertaken hundreds of years in the past. When the wreck of the Mary Rose, King Henry VIII’s magnificent flagship, was finally raised in 1982, the bones of about 180 of those who perished were recovered. The ship had gone down in the Solent on a warm summer’s evening in 1545, in full sight of land, while leading an attack on an invading French fleet. All but about twenty-five of the crew of 415 were lost.
As expected, analysis of the bones showed them all to have been male, and mostly young—the majority were under thirty and some no older than twelve or thirteen. The ship also carried over three hundred longbows and several thousand arrows, so it is likely that there was a strong contingent of the much-feared English bowmen on board. Examination of the bones by an osteoarchaeologist, Ann Stirland, revealed a disproportionate incidence of os acromiale: it was present in some 12 per cent of scapulae.
The scapulae of modern-day archers who take up the activity as youngsters often show os acromiale on one side, particularly the left, as this is the arm most commonly used to brace and take the strain of the bow. It is therefore not unreasonable to surmise that many of the men on the Mary Rose would have been taught archery from a very early age and that the presence of the acromial ossicle (little bone) was a visible remnant of their strenuous training.
The human remains from the Mary Rose had all been taken to Ann’s cottage near Portsmouth for storage and analysis. This is not something that would happen today: the bones would be secured in a laboratory for safety’s sake. But in those less regimented times I was able to sit with Ann in her dining room one glorious summer afternoon, with all the bones laid out on a table, marvelling at the remarkable preservation of these incredible pieces of history. The os acromiale was something she was very excited about and we spent hours trying to reunite these little lumps of bone with the scapulae from which they had originated by searching for the best fit, not always successfully. I felt really honoured to be allowed not only to look at, but to handle these remains, and the memory of that afternoon, passed in the companionable silence of scientific study, is one I cherish. Every time I see a documentary about the Mary Rose, it transports me back to that perfect summer and Ann’s boundless enthusiasm, her copious cups of tea and a tremendous amount of laughter and wonder.
7
The Pelvic Girdle
“The pelvis is a literal gateway to evolution”
Holly Dunsworth
Evolutionary Anthropologist
The second girdle in the body, the pelvic girdle, extends all the way around the torso from the sacrum at the back to the pubic bones in front. This is the junction where the weight of the upper part of our body is transferred from our spine to our hips, and from there down through our lower limbs to the ground.
Each of the innominates, the two paired hip bones of which it is comprised, is constructed from three parts: the ilium (at the back and at the top), the ischium (at the bottom) and the pubis (at the front). The ilium is the section that forms a joint with the sacrum at the back and it has broad, flat blades for muscle attachment. It is the ilium that has the prominent lump we can feel on our hips on each side. The ischium (specifically the ischial tuberosity) is the bit that we sit on. The pubic bones are at the front and articulate with each other in the midline behind the area where our pubic hair grows.
The ilium forms first, in the second month of fetal life, followed by the ischium at four months and lastly the pubis, at around five to six months. At birth, the pelvic girdle is comprised of twenty-one separate bones (fifteen in the sacrum and three in each of the two hip bones). The three bones on each side will eventually fuse together towards the end of puberty to make the single bone known as the innominate—rather incongruously, given that this literally translates as “no name.” Fusion takes place, at around five to eight years, between the ischium and pubis, so that by the age of eight both innominates are in two parts. Between eleven and fifteen years, the ilium and the combined ischium and pubis all come together in the cup-shaped acetabulum of the hip joint. Each innominate will finally be complete when we are around twenty to twenty-three, once the crest that runs along the top of the bone stops growing.
The innominate is a rich source of information for the forensic anthropologist. It may be of little value in helping with height or ancestral origin, but it comes into its own in establishing sex and age at death. It is said that, presented with a whole skeleton to examine, we will probably be able to assign sex correctly around 90 per cent of the time. But if you had to do this from just one bone, you would always choose the innominate, which can tell us what we need to know to get this right about 80 per cent of the time.
The innominate would also be the top choice for age determination, as it can assist us in coming to a sound decision right the way through from the early years into old age. Age-related changes in adults between twenty and forty may be seen in the surfaces of both the sacroiliac joints and the pubic symphysis between the two pubic bones at the front. Here the alterations can be both developmental and degenerative. These are well documented by research, enabling the bone to continue to give us guidance on the likely age of a deceased person well beyond their third decade.
The pelvis is divided by a well-defined rim into the false (or greater) pelvis above and the true (lesser) pelvis below. The false pelvis is so called because it is generally considered to be part of the abdominal cavity. This provides large, flat sites for muscle attachment and holds some of the abdominal viscera. The true pelvis beneath is a much tighter space, which houses structures such as the bladder, the rectum and the internal reproductive organs.
The rim separating the false from the true pelvis is known as the pelvic brim, or pelvic inlet. At the other end we have the pelvic outlet, bounded by the coccyx at the back and the ischial tuberosities to either side. The inlet and outlet are the gateways of the pelvic cavity, through which our soft tissues, such as our gut, nerves and blood vessels, pass. It is also the transit route for material that we wish to expel from the body: the products of our urinary tract, our digestive system and our internal reproductive organs (ejaculate in men, menstrual matter and, of course, babies in women).
That the female pelvis is so firmly associated with childbirth explains its particular value in the determination of sex from skeletal remains. It needs not only to retain its ability to perform its full-time functions—keeping our guts inside and allowing us to walk on two legs—but to be ready to accommodate the biggest thing ever to pass into the pelvic inlet and out through the pelvic outlet: a baby’s head. Once that descends through the pelvic inlet, trust me, you sure as heck want to get it out of the pelvic outlet as swiftly as possible.
Until the hormones associated with puberty kick in with a vengeance—especially the primary female hormone, oestrogen—the pelvis is equally paedomorphic in both sexes, which means we are unable to determine the sex of a child from the pelvic bones. In general, whereas increasing levels of oestrogen change the shape of the female pelvis quite dramatically, the male pelvis retains its more childlike form and just gets bigger in response to larger muscle mass.
The reaction of the female pelvis to the effects of oestrogen is to prepare the girdle in a variety of ways for its role as a birth canal. For example, during pubertal growth, the back of the pelvis and the sacrum are raised, straightening the hook-shaped greater sciatic notch (through which the sciatic nerve passes from the pelvis to the lower limbs) to adopt a more obtuse, or open, angle. This creates a more spacious pelvic cavity with a wider pelvic inlet and outlet, aided by changes to the sacrum, which broadens in the female. Her pubic bones, which remain fairly triangular in the male, become longer and squarer. This helps to increase the size of both the pelvic inlet and the pelvic outlet. The ischial tuberosities will be further apart in the female than in the male. If you are in any doubt, look at the saddle on an old-
fashioned bicycle. The manufacturers used to make them broader for women’s bikes to suit the wider gap between ladies’ ischial tuberosities.
These minor modifications to the female pelvis are all designed to work together to allow the successful passage of a fetal head. And most of the time, they do. However, when it comes to childbirth, considering that the pelvis is already jam-packed with all Mum’s internal wiring, plumbing and viscera, there is still precious little room to squeeze a great big head through that tiny space. It is said that, on average, the female pelvic canal is an inch narrower than a baby’s head, so something has to give if the head is going to get through the birth canal safely. The truth is that both mother and baby compromise just a little, because, after all, only an inch or so has to be found.
As the time for birth approaches, Mum’s ovaries and placenta increase the production of a hormone called, rather appropriately, relaxin. This helps to rupture the membranes around the fetus and soften the cervix. There is some evidence that it also softens the ligaments that hold the normally tight pelvic ring together and so permits a little bit of movement. At the same time, since the bones of the baby’s skull are not yet fused, as the head passes through the slightly loosened pelvic canal, they can ride over each other, squeezing the brain beneath. This is why it is not uncommon for babies to be born with slightly deformed skull shapes, which generally rectify themselves shortly after birth.
Quite often we find pits and grooves at the sites of joints in the pelvis, specifically in the joints between the sacrum and the ilium and between the two pubic bones at the front. In the past, scientists considered these to be indicators of childbirth: they even called them “scars of parturition.” Some even went as far as to equate the number of pits present with the number of live births a woman had accomplished, one pit for each delivery. Time and research has shown this to be nonsense. If my Uncle Willie’s brothers and sisters had all lived there would have been twenty-four of them. His poor mother was pregnant virtually her entire adult life. If a pit had been formed every time she had given birth, her pelvis would have looked like Swiss cheese.
While these pits are noted much more frequently in females, they do occasionally occur in males, too, so clearly they can’t be fully explained by childbirth. When we do see them, they are nevertheless generally a good indicator of the female sex, although they are more likely to be scars caused by ligaments stretching at the joint surfaces than evidence that a woman has delivered a baby.
It is not unusual for fetal bones to be found within the pelvic cavity of a skeleton and it is something that a forensic anthropologist will routinely look for. Childbirth is a hazardous time for both Mum and baby and fetomaternal mortality is always a risk. There is also a rare phenomenon which merits just a little mention. A lithopaedion, Greek for “stone baby,” can form either from a primary abdominal pregnancy or from a secondary abdominal implantation following an ectopic pregnancy.
The egg is usually fertilized high up in the fallopian tube, but if this occurs as it crosses the gap between the ovary and the tube, it can sometimes be deflected into the abdominal cavity. In an ectopic pregnancy, the fertilized egg does not get as far as the uterus and instead implants in the fallopian tube. Should the tube rupture, the embryo can migrate into the abdominal cavity. Alternatively, if the egg is fertilized before it enters the fallopian tube, it may fail to cross the gap between the surface of the ovary and the fimbriae of the tube and embed directly in the abdominal cavity.
The embryo is a genuine parasite, and provided it can implant successfully on to an abdominal surface, it can survive and develop outside the uterus, sometimes for as long as twelve to fourteen weeks. This is the stage when a fetus normally shifts its pole for placental implantation, and if a placenta cannot get hold of a sufficient blood supply, a function for which the uterus is specifically designed, the abdominal pregnancy will usually fail and the fetus will die. However, lithopaedia have survived beyond this age. The oldest we know of lived for thirty weeks.
Since the fetus cannot be expelled naturally—it has no way out—and may in some instances be too large to be absorbed by the mother’s body, it begins to calcify. It is likely that the conversion into bone is an autoimmune response to protect the mother from infection in the event that the fetus starts to decompose. And so it is slowly turned into a stone baby.
The medical literature recounts fewer than 300 authenticated cases of lithopaedia and in most the mother was unaware that the stone baby even existed until it was discovered during a pelvic examination, often for something unconnected. Women have gone on to give birth to other live children without knowing they had a secret passenger on board. A stone baby can weigh as much as four pounds, yet in some instances, a lithopaedion has remained in the body undetected for forty years or more.
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The pelvis is susceptible to fracture, especially from impact in a fall, crush injury or road accident. It is a common outcome when pedestrians are hit by vehicles. Collisions in which the knees slam into a car dashboard are a particular hazard: the femora can plough into the hip socket and break the pelvis into many pieces. This type of fracture can be very debilitating as there is a risk of nerve damage, which may result in incontinence and impotence. So please, don’t sit in a car with your knees touching the dashboard. Move your seat further back and stretch out your legs.
Because the pelvis is a ring, a break in one part of the structure is frequently accompanied by a second fracture or further damage in another: these are known as unstable fractures, and such injuries, and their consequences, can be complex. When a person has survived them, the scars remain in the bones for the forensic anthropologist to find and as the fractures will almost certainly have required hospital treatment, there are usually X-rays, CT or MRI scans on record for comparison.
It is also not unusual for gunshot injuries to manifest in the pelvis. I was asked in both of the following separate cases to attempt to retrieve bullets from exhumed skeletal remains to try to shed some light on who may have been responsible for each shooting. These men had been dead for some forty years, but in both instances, the question of who had fired the gun was now of some importance to wider investigations. Both had been buried without postmortem examinations and without the removal of any ballistic evidence. This seems inexplicable today, but perhaps it was just a symptom of the time and place in which they lived.
The first victim was a young man of eighteen who had been standing on a street corner in Belfast talking with a friend when he was shot in the leg from a passing car—a classic drive-by shooting. He was rushed to hospital but died later on the operating table. The medical notes identified a ballistic entry wound but no exit, suggesting that the bullet may have stayed within his body.
As part of legacy investigations, a decision was made to exhume his remains and examine his skeleton for any ballistic evidence. He had been the first of his family to be placed in the grave, but three relatives had since been buried on top of him and the process of exhumation was going to be lengthy and complex.
The difficulty of this grim task was exacerbated by the weather. Exhumations always seem to be required when it is cold, dark and wet. It makes for a miserable scene as everyone huddles into tents to shelter from howling gales and lashing rain. You also know from bitter experience that the grave is going to become waterlogged and that you will soon be up to your knees in mud and water.
The most recent burial in the grave was that of a child, who had been interred in a cotton shroud that was visible very close to the surface. These remains were very carefully exhumed by hand using a trowel and placed gently into a body bag for reburial at a later date. A mechanical digger was then employed to strip away thin layers of soil until the top of the first adult coffin lid was uncovered.
At this stage, all that was needed was a quick jump into the grave to check the name on the plate, open the lid, transfer the skeletal remains into a body bag and hand out the disintegrating MDF pieces of the coffin.
But by the time we got down to the lid of the second adult coffin a ladder was required. When a grave is deep it is difficult to manoeuvre in the tight space. For a lady of advancing years, and “wide in the beam,” as my father used to say, it is always helpful to have a younger, fitter, thinner colleague working with you. Lucina, bless her, knows that she will always end up being sent down the hole.
The second set of skeletal remains were lifted from their coffin without incident and transferred to a body bag. The body bags, complete with their contents, were stored on site in what is known as a transportation coffin, which is really just an oversized wooden box, to await reinterment when the investigation was over.
The coffin of the young shooting victim was located exactly where the cemetery records said it would be, which, I can tell you from personal experience, is not always the case. We checked the name on the plate, removed the lid and transferred the remains to a body bag as the coffin was too rotten for us to try to lift it intact. A metal detector was passed over the coffin, and, once all the detritus had been removed, it was used again to scan the soil on the floor of the grave to make sure that no metallic pieces of evidence had been missed. Nothing was found.
The body bag was radiographed, using a mobile X-ray machine that had been brought to the cemetery. Everything was done in the presence of family members and their legal representative, to ensure that all aspects of the exhumation were open and transparent. For understandable reasons, there was considerable distrust between the victim’s relatives and the police. The family had also engaged their own forensic anthropologist to monitor the operation. It was hoped that these measures would instil a spirit of co-operation and help with the healing process.
