by Sue Black
Perhaps we only really understand the value of something when we lose it. Try to imagine your life without one or indeed both of your hands. You might think it is only those serving in combat zones around the world, where roadside bombs or improvised explosive devices are a constant threat, who need to worry about losing parts of their bodies. But we don’t have to be on active service to put ourselves at risk: simply doing nothing is enough. Some six thousand upper and lower limb amputations occur each year on the NHS as a result of type 2 diabetes.
We use our hands not only for practical purposes but to clasp, hug, caress and to greet. The hand is served by a wealth of nerve endings that convey touch and warmth directly to the brain. The fact that almost a quarter of the body’s sensory capacity is given over to the hand almost justifies elevating it to the status of an organ of sensory exploration in its own right.
Modern technological prostheses may be capable of replacing some of the motor functionality of the hand, enabling amputees to undertake basic tasks, but we do not have the technology that can recreate its innate sensitivity or the human connections made by a living hand, either for the toucher or the touchee. Even replicating the complex and subliminal gestures we use to communicate remains beyond the scope of replacement limbs, amazing though they may be in what they can now do compared with their more primitive predecessors.
Most of us find it extremely challenging to talk without the involvement of seemingly involuntary hand movements that either directly convey certain points or emphasize them. When we cannot use our voice, we have learned to rely on our hands and mouths to produce gestures and shapes to express ourselves. Technology now provides new options for those who lose their sight, but the art of reading Braille, which entails distinguishing between and interpreting the world of information contained in a pattern of little raised dots, is a perfect illustration of the value of the volume of nerve endings we have in our fingertips.
The intricacy of the anatomy of the hand, and the fact that it is so often seen in motion, make it a challenging part of the body for an artist to capture with accuracy. The detail reproduced by Leonardo da Vinci, marvellous though it is, pales in comparison with Albrecht Dürer’s drawings of hands, in which you can almost touch the veins, the tendons and the wrinkled skin. In his old age, and in poor health, Henry Moore drew his own hands as a representation of the ageing body. “Hands can convey so much,” he said. “They can beg or refuse, take or give, show content or anxiety. They can be young or old, beautiful or deformed.”
To get an idea of what a miracle of engineering the hand is, let’s take one simple movement, the action of picking up and holding a pen, and look at what our body has achieved to enable us to perform it.
First of all, it had to develop a pentadactyl (five-fingered) limb. Paired elevations, or limb buds, begin to form in the neck region of a human embryo at around 26 days of intrauterine life. By day 33, we have a recognizable hand plate at the end of the upper limb. At this point it looks a bit like a paddle as there are no separate fingers yet. Five days later, the edge of the paddle takes on a crenulated appearance as the cells in the interdigital spaces start to die and the tips of the fingers begin to emerge. The fingers gradually become more distinct as the cells between them continue to die off.
When these cells don’t do their job all the way down to the pre-destined position, we end up with webbed fingers. Sometimes the fingers don’t separate properly at all, a condition called syndactyly, whereby two or more fingers (or, more commonly, toes) remain fused together. This can be remedied by a relatively simple operation to separate them, resulting in two fully functioning digits.
By day 41, the neurovascular structures have penetrated deep into the hand plate, ensuring that future soft tissue will have access to a blood and nerve supply and all of the thirty-four (or so) muscles required to operate each hand will be in working order. By day 47, the hand can rotate, and by the next day cartilage, the precursor of the bones, will have started to form. Over the next eight days, cells die in pre-programmed locations in the cartilaginous mass to create joint spaces between the future bones. This is vital if the hand is to become a flexible multi-functioning tool and not remain little more than a static shovel.
By day 56, the thumb, known anatomically as the pollex, has rotated into a different plane from the other digits to produce our prehensile grip. The ability to bring the pad of the thumb into contact with the pads of all the other fingers is known as opposition. This is the feature that distinguishes us primates from the rest of the animal kingdom: your average dog, cat, horse or capybara simply can’t do it.
By now swellings have also appeared on the pads at the end of the fingers, which are jam-packed with the nerve endings critical to the sensitivity of the hand as an exploratory tool. This is also where our fingerprints will form.
And so, providing all has gone well, six weeks into your development, you will already be equipped with a perfectly functioning pair of hands. You will quickly learn to draw comfort from them (very early on, babies can be seen on ultrasound imaging sucking their thumb or a finger). It will take you a little while after you are born to learn how to use them smoothly and with precision, but the “reach” and “grasp” reflexes can be strong in newborn babies. Some palaeontologists believe this to be a remnant of the need to cling on to our mothers tightly during a previous arboreal existence.
So, we have the required pair of hands. What do we need to do with them to pick that pen up? First, our brain recognizes it as a pen, and we have had the thought motivating us to pick it up. To reach out for it, our brain needs to send impulses from our precentral cortex, down our spinal cord and out through the spinal nerves that serve the upper limb (located in the neck region, where the limb first formed). These pass through the brachial plexus, a spaghetti junction of nerves in the armpit, and then fan out to the muscles we have decided we need to move to perform our action. We must flex the deltoid to lift our upper limb, the serratus anterior to propel it forward and then contract at least six muscles in our forearm to activate the wrist and the joints of the index finger and thumb. To make sure the movement is smooth, our cerebellum at the base of our brain oversees the operation and irons out any potentially ragged manoeuvres.
Now we can feel the pen between our thumb and index finger through those sensory nerves in our fingertips, which have sent their signal all the way back to the post-central region of the brain to tell it that the pen is in our hand, confirming what our eyes are also reporting. Although we think we are feeling the pen in the pincer action between the thumb and index finger, this is really taking place in the brain.
To hold the pen where we want it, we then turn our wrist to a semi-prone position, using a couple of muscles in our forearm, and arrange our thumb so that it is flexed at both joints and our index finger so that it is flexed at two joints but extended at the third. All the other digits of the hand adopt a relaxed but contracted position so that we can tuck them out of the way in our palm.
And all this has happened before we have even started to think about what we are going to write. The human body is utterly amazing and none of its accomplishments more so than the delicate ballet performed by the hand, all reliant on a vast supporting cast that have been rehearsing their respective roles since long before we were born. We make all of these movements without even thinking, just taking it for granted that everything will be in the right place, correctly wired.
Clearly such feats demand a complex underlying structure, and so it is not surprising that of the 200-plus bones in the adult human skeleton, at least fifty-four of them, over a quarter, are found in the paired hands. The bones are small as their versatility and flexibility of movement require short segments to accommodate muscle attachment. There are normally eight carpal bones in the wrist region, five metacarpals forming the flat of the hand and fourteen phalanges (three in each digit apart from the thumb, which only has two) with a couple of tiny sesamoid bones thrown in for good measure in t
he tendons of muscles associated with the thumb.
The small size of the bones makes them hard to recognize outside the context of the rest of the skeleton. This is certainly true of children’s hands, as their components can be so tiny they could be mistaken for something like lentils, grains of rice or small stones. And it is not unusual for forensic anthropologists to have to search for hand bones, as each of the bony parts may fall away as the body decomposes. Human hands tend to be uncovered, and they stick out of the bottom of sleeves, making them easy prey for scavengers to carry off. So, as we have seen, when a body is discovered without its hands, we are not immediately concerned that they have been removed in a criminal act, although we do, of course, always check for cut marks on the remaining bones, just in case. In most circumstances what we will find are the marks left behind by the canine teeth of a fox, sometimes a badger. Feral cats and dogs will also target hands.
While it is fairly common for a body to be found minus its hands, what is less common is a hand turning up without a body. Of course, if one does, it doesn’t necessarily mean that its owner is dead, as it could be the result of amputation, either accidental or deliberate. And fingers have been known to be removed from kidnap victims to extort ransoms, even if this is a rarer event in real life than it is in crime novels and films.
When an isolated hand or finger is found, how do we know that it is human? My colleagues and I are used to police officers phoning to tell us that they have found a hand on the beach. So used to it, in fact, that our initial response is inclined to be almost blasé. Before even looking at the images we will ask them to send us, we will probably offer the opinion that it is likely to be a seal flipper. It is amazing just how closely a decomposing seal flipper can resemble the human hand. A seal flipper is, like the human hand, a terminal appendage on a pentadactyl (five-digit) limb. There is some debate about the evolution of the pentadactyl limb, but it is fairly characteristic of all four-footed animals, which include amphibians, reptiles, birds and mammals.
It is likely that these appendages evolved from the paired fins of primitive fish as they adapted to the need to move around on land. The basic form has been modified in different species, mainly through the loss or fusion of bones in the “foot” or “hand.” The ungulates are a good example of this. Their pentadactyl limb has evolved hooves to meet the specific requirements of their form of locomotion. Some are odd-toed (perissodactyl) ungulates, such as horses, others even-toed (artiodactyl) ungulates, such as camels; there is also an order “subungulates”—paenungulata, meaning “almost ungulates”—which includes elephants.
We had one of these routine “hand found on the beach” phone calls one day from a police officer on the west coast of Scotland. We went through the usual motions, asking him to send us a photo, which we would, of course, check, while informing him airily that it was most likely to be a seal flipper and he shouldn’t be too worried. Such reassurances take the immediate pressure off the police. Investigating the provenance of a dismembered human hand would mean gearing up for a large-scale operation involving air, land and sea searches and coroners and procurators fiscal, not something it is advisable to launch prematurely.
However, when the photos arrived it was clear that this was definitely a hand, not a flipper—and it was very nearly human. But not quite. No visible skin remained owing to advanced decomposition but the proportions were all wrong: the thumb was very short and the fingers very long. This was the hand of a non-human primate, probably a chimpanzee. There was no evidence of cut marks to suggest it had been removed with a bladed implement, and no obvious signs of predation, either. How on earth do you get a chimp’s hand on a Scottish beach?
Perhaps it was from a wildlife park, or a sanctuary specializing in rescuing non-human primates; perhaps from the burial of a pet. Or it could have been dumped overboard from a boat shipping illegal animal parts for homeopathic medicines or black magic practices. We never found out, but we never again assumed that every hand on the beach would be a flipper, and it made us think twice about nonchalantly voicing this opinion before taking a proper look.
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As we saw in Chapter 8, hands, and fingers in particular, are often lost by those who die in a fire. As there is very little soft tissue or fat covering the hands, it doesn’t take long for them to burn down to the bone and for the bone to crumble into ashes. So it is important when recovering a body from a fire scene to thoroughly search the area around the base of the forearm to ensure that all the ashed fragments of the hand are retrieved. Given that these are so difficult to identify, it is increasingly being seen as essential to include a forensic anthropologist in any team dealing with a fatal fire, during both the recovery and subsequent investigation stages.
Our skills and anatomical knowledge have proved to be of genuine assistance to police officers and fire investigators. They are always amazed that we can pick up a tiny fragment of burned matter, which to them looks like nothing more than a piece of charred wood or a small stone, and tell them that it is a finger or a wrist bone.
Unfortunately, the input of forensic anthropology has not always been seen as crucial in these investigations. It is the way of the world that, too often, it takes a mistake to bring about improvements in procedures. This is precisely what occurred in one tragic case, in which the police only sought my opinion in the first place because the local forensic pathologist happened to be on holiday.
There had been a fire that, heartbreakingly, had resulted in the death of two little boys. It was sparked by an electrical fault in a remote, idyllic Victorian cottage in the Highlands which went up like a tinder box because of its original pitch pine features. The fire engines had a long way to travel and had to negotiate a winding, single-track road to finally reach the cottage. With nobody to help until they arrived, the parents battled the flames to try to rescue their sons, who were trapped in their bedroom, but they were beaten back by the ferocity of the fire and the thick, black smoke. It was believed that, mercifully, the boys probably died in their beds as they slept, overcome by the smoke. I cannot imagine the torment of watching your house burn, with your children inside it, powerless to save them.
Eventually the fire service got the blaze under control and, when the building was finally declared safe, they began the grim search for the bodies of the two boys. The roof had collapsed and the rafters and slates had caved into the cottage, so everything had to be lifted out of the way by hand as the shell of the building was searched, room by room. The heavy rafters were removed carefully and stacked outside at the front of the house. The boys, still in their beds, were found buried under slates and timber. Once the debris was cleared, their badly burned bodies were transferred to the mortuary for examination.
One child had been found intact but it was clear that significant parts of the older boy were missing. It was explained to the family that it was likely the rest of the body had been completely incinerated and would not be recovered. The children were buried in little white coffins as the mourners marvelled at the stoicism and dignity of these parents who had lost everything.
The couple returned to their cottage regularly as they tried to come to terms with their loss and work out what could be salvaged from the ruins of their home, perhaps as mementos of happier times. Two weeks after the fire, they were there laying flowers, as they always did, when they noticed a little pile of bones on the grass in their garden.
They contacted the police and were reassured by an officer who came out to have a look at the bones that they were most likely to be from an animal. He was a local, a countryman, and he thought they were probably cat bones. He told the couple not to worry, scooped the bones into an evidence bag and took them to the mortuary. As the forensic pathologist was on holiday, the police asked me if I could please go over to the mortuary and give these cat remains the once-over to reassure the family that these were indeed what they were.
When there is an anticipation that this kind of examination is a formality a
nd you will just be going through the motions, nobody is really interested in what you are doing, so support in the mortuary was minimal. Unfortunately, this was to be one of those occasions when I was going to rock the boat, because I was about to utter the unimaginable: these little “cat” bones were, without a shadow of a doubt, human, and from a young child of between four and six years of age.
There was an assortment of bones, including parts of the vertebral column, little fragments of rib and some of the small bones from the wrist. Several of them bore tooth marks. To the police, they were just little ivory-coloured flecks that could have been anything. The easiest course of action in such a situation is to challenge the anthropologist, especially since I was telling them something they were not happy to hear.
Asked if I was sure about this, I confirmed that I was. Nevertheless I was questioned hard about how I could be so certain. I replied that I had written the textbook on the identification of juvenile bones. Not only could I tell them which region of the body the bones were from, I could tell them which side, name them all individually and give them an age estimate.
The temperature in the mortuary dropped another ten degrees. It was, it seemed, more acceptable for the expert to be wrong than for an unwelcome opinion to be correct. As the police left me to finish my note-taking, I asked if a report was required from me. Surprisingly, I was told that it was not. They would rather wait for the forensic pathologist to come back from his holiday.
I went home. I felt very uncomfortable that something I knew to be categorically true was being questioned and that there was nothing I could do about it. I thought about the child, the family and the fire. I thought about how the bones might have got out into the garden. I thought about the implications of what I had to say going unsaid and I decided to write a report anyway, if only for my own peace of mind. Experience has taught me that, however much you think you will remember, if you don’t write it down at the time, you quickly forget details. I also know that if something is not recorded in writing there will be no evidence that it ever took place.