The body, p.42
The Body, page 42
The greatest mystery of all is why some people get Alzheimer’s and others don’t. Several genes have been found to be associated with Alzheimer’s, but none has been directly implicated as a root cause. Just getting old vastly increases your susceptibility to Alzheimer’s, but then the same could be said of almost all bad things. The more education you have had, the less likely you are to get Alzheimer’s, though having an active and questing mind, as opposed to just racking up a lot of classroom hours in one’s youth, is almost certainly what keeps Alzheimer’s at bay. Dementias of all types are considerably rarer in people who eat a healthy diet, exercise at least moderately, maintain a sound weight, and don’t smoke at all or drink to excess. Virtuous living doesn’t eliminate the risk of Alzheimer’s, but it does reduce it by about 60 percent.
Alzheimer’s accounts for between 60 and 70 percent of all dementia cases and is thought to affect some fifty million people around the world, but Alzheimer’s is only one of about a hundred types of dementias, and it is often difficult to distinguish among them. Lewy body dementia, for instance, is highly similar to Alzheimer’s in that it involves a disturbance of neural proteins. (It’s named for Dr. Friedrich H. Lewy, who worked alongside Alois Alzheimer in Germany.) Frontotemporal dementia arises from damage to the frontal and temporal lobes of the brain, often because of a stroke. It is often highly distressing to loved ones because victims frequently lose inhibitions and the ability to control impulses, so they tend to do embarrassing things—shed clothes in public, eat food abandoned by strangers, steal from supermarkets, and so on. Korsakoff’s syndrome, named for a nineteenth-century Russian investigator, Sergei Korsakoff, is a dementia that arises most often from chronic alcoholism.
Altogether, one-third of all people over the age of sixty-five will die with some form of dementia. The cost to society is huge, yet almost everywhere research is curiously underfunded. In Britain, dementias cost the National Health Service £26 billion a year, but receive only £90 million annually in research funding, compared with £160 million for heart disease and £500 million for cancer.
Few diseases have been more resistant to treatment than Alzheimer’s. It is the third most common cause of death among older people, exceeded only by heart disease and cancer, and we have no effective treatment for it at all. In clinical trials, Alzheimer’s drugs have a 99.6 percent failure rate, one of the highest in the whole field of pharmacology. In the late 1990s, many researchers were suggesting that a cure was imminent, but that proved premature. One promising treatment was withdrawn after four people taking part in trials developed encephalitis, an inflammation of the brain. Part of the problem, as mentioned in chapter 22, is that Alzheimer’s trials must be done on laboratory mice, and mice don’t get Alzheimer’s. They must be bred to grow plaques inside their brains, and that means they respond to drugs in different ways than humans would. Many pharmaceutical companies have now given up altogether. In 2018, Pfizer announced that it was withdrawing from research into Alzheimer’s and Parkinson’s disease and cutting three hundred jobs from two research facilities in New England. It is a sobering thought that poor Auguste Deter, if she presented herself to a doctor today, would be no better off now than she was with Alois Alzheimer almost 120 years ago.
IV
IT HAPPENS TO us all. Every day, around the world 160,000 people die. That’s about 60 million fresh bodies a year, roughly equivalent to killing off the populations of Sweden, Norway, Belgium, Austria, and Australia year after year. On the other hand, it’s only about 0.7 deaths per 100 people, which means that considerably less than one person in a hundred dies in any given year. Compared with other types of animals, we are awfully good at surviving.
Getting old is the surest route to dying. In the Western world, 75 percent of deaths from cancer, 90 percent from pneumonia, 90 percent from flu, and 80 percent from all causes occur in people sixty-five years of age or older. Interestingly, in the United States no one has died of old age since 1951, at least not officially, for in that year old age was banished as a cause from death certificates. In Britain, it is still allowed, though not much used.
Death is, for most of us, the most terrifying event imaginable. Jenny Diski, facing impending death (in 2016) from cancer, wrote movingly in a series of essays for the London Review of Books about the “excruciating terror” of knowing one is soon to die—“the razor-sharp claws digging into that interior organ where all dreaded things come to scrape and gnaw and live in me.” But we do seem to have some measure of defense mechanism built into us. According to a 2014 study in the Journal of Palliative Medicine, between 50 and 60 percent of terminally ill patients report having intense but highly comforting dreams about their impending passing. A separate study found evidence of a surge of chemicals in the brain at death, which may account for the intense experiences often reported by survivors of near-death incidents.
Most dying people lose any desire to eat or drink in the last day or two of life. Some lose the power of speech. When the ability to cough or swallow goes, they often make a rasping sound commonly known as a death rattle. It can sound distressing but seems not to be to those experiencing it. However, another kind of labored breathing at death, called agonal breathing, may very well be. Agonal breathing, in which the sufferer can’t get enough breath because of a failing heart, may last only for a few seconds, but it can go on for forty minutes or more and be extremely distressing to both victim and loved ones at the bedside. It can be stopped with a neuromuscular blocking agent, but many doctors won’t administer it, because it inevitably hastens death and is therefore thought unethical or even possibly illegal, even though death is just around the corner anyway.
We are extraordinarily sensitive about dying, it seems, and often take the most desperate steps to put off the inevitable. Almost everywhere, overtreatment of dying people is routine. Among those dying of cancer in America, one in eight receives chemotherapy right up to the last two weeks of their lives, long past the point where it is effective. Three separate studies have shown that cancer sufferers receiving palliative care in their final weeks rather than chemotherapy actually live longer and suffer much less.
Predicting deaths, even among the dying, is not easy. As Dr. Steven Hatch of the University of Massachusetts Medical School has written, “One review found that, even among terminally ill patients whose median survival is only four weeks, doctors were correct to within a week of survival in only 25 percent of cases, and in another 25 percent their predictions were wrong by more than four weeks!”
Death becomes apparent very quickly. Almost at once the blood begins to drain from the capillaries near the surface, leading to the ghostly pallor associated with death. “A man’s corpse looks as though his essence has left him, and it has. He is flat and toneless, no longer inflated by the vital spirit the Greeks called pneuma,” wrote Sherwin Nuland in How We Die. Even to someone unused to dead bodies, death is usually instantly recognizable.
Tissue deterioration starts almost at once, which is why “harvesting” (surely the ugliest term in medicine) organs for transplant is such an urgent business. Blood pools in the lowest parts of the body, as gravity demands, turning the skin there purple in a process known as livor mortis. Internal cells rupture and enzymes spill out and begin a self-digesting process known as autolysis. Some organs function longer than others. The liver will continue to break down alcohol after death, even though it has absolutely no need to do so. Cells, too, die at different rates. Brain cells go quickly, in no more than about three or four minutes, but muscle and skin cells may last for hours—perhaps a whole day. The famous muscle stiffening known as rigor mortis (literally “stiffness of death”) sets in between thirty minutes and four hours after death, starting in the facial muscles and moving downward through the body and outward to the extremities. Rigor mortis lasts for a day or so.
A corpse is still very much alive. It’s just not your life any longer. It’s the bacteria you leave behind, plus any others that flock in. As they devour the body, gut bacteria produce a range of gases, among them methane, ammonia, hydrogen sulfide, and sulfur dioxide, as well as the self-explanatorily named compounds cadaverine and putrescine. The smell of a rotting corpse usually becomes horrible within two to three days, less if the weather is hot. Then, gradually, the smells begin to ease until there’s no remaining flesh and thus nothing left to cause odor. Of course, the process can be disrupted if the body falls into a glacier or peaty bog, where bacteria can’t survive and proliferate, or is kept very dry so that the body mummifies. It is a myth, and physiological impossibility, incidentally, that hair and nails continue to grow after death. Nothing grows after death.
For those who choose to be buried, decomposition in a sealed coffin takes a long time—between five and forty years, according to one estimate, and that’s only for those who are not embalmed. The average grave is visited for only about fifteen years, so most of us take a lot longer to vanish from the earth than from others’ memories. A century ago, only about one person in a hundred was cremated, but today three-quarters of Britons and 40 percent of Americans are. If you are cremated, your ashes will weigh about five pounds.
And that’s you gone. But it was good while it lasted, wasn’t it?
ACKNOWLEDGMENTS
I don’t believe I have ever been indebted to more people for expert help and guidance, more generously given, than I have with this book. In particular I wish to thank two people for their especially close help: my son Dr. David Bryson, pediatric orthopedic fellow at Alder Hey Children’s Hospital in Liverpool, and my good friend Ben Ollivere, clinical associate professor of trauma surgery at the University of Nottingham and a consultant trauma surgeon at Queen’s Medical Centre in Nottingham.
I am also much indebted to the following:
In England: Dr. Katie Rollins, Dr. Margy Pratten, and Dr. Siobhan Loughna of the University of Nottingham and Queen’s Medical Centre, Nottingham; Professor John Wass, Professor Irene Tracey, and Professor Russell Foster of Oxford University; Professor Neil Pearce of the London School of Hygiene and Tropical Medicine; Dr. Magnus Bordewich of the Department of Computer Science at Durham University; Dr. Karen Ogilvie of the Royal Society of Chemistry; Daniel M. Davis, professor of immunology and director of research at the Manchester Collaborative Centre for Inflammation Research at the University of Manchester, and his colleagues Jonathan Worboys, Poppy Simmonds, Pippa Kennedy, and Karoliina Tuomela; Professor Rod Skinner of Newcastle University; Dr. Charles Tomson, consultant nephrologist at Newcastle upon Tyne Hospitals; and Dr. Mark Gompels of North Bristol NHS Trust. Special thanks also to my good friend Joshua Ollivere.
In the United States: Professor Daniel Lieberman of Harvard University; Professor Nina Jablonski of Penn State University; Dr. Leslie J. Stein and Dr. Gary Beauchamp of the Monell Chemical Senses Center in Philadelphia; Dr. Allan Doctor and Dr. Michael Kinch of Washington University in St. Louis; Dr. Matthew Porteus and Professor Christopher Gardner of Stanford University; and Patrick Losinski and his helpful staff at the Columbus Metropolitan Library in Columbus, Ohio.
In the Netherlands: Drs. Josef and Britta Vormoor, Professor Hans Clevers, Dr. Olaf Heidenreich, and Dr. Anne Rios of the Princess Máxima Center for Pediatric Oncology in Utrecht. Special thanks also to Johanna and Benedikt Vormoor.
I am also much indebted to Gerry Howard, Dame Gail Rebuck, Susanna Wadeson, Larry Finlay, Amy Black, and Kristin Cochrane at Penguin Random House, to the brilliant artist Neil Gower, to Camilla Ferrier and her colleagues at the Marsh Agency in London, and to my children Felicity, Catherine, and Sam for much willing assistance. Above all, and as always, my greatest thanks go to my dear and saintly wife, Cynthia.
NOTES ON SOURCES
The following is intended as a quick guide for those who wish to check a fact or do further reading. Where a fact is commonly known or widely reported—the functions of the liver, for instance—I have not cited the source. On the whole, sources are listed only where assertions are specific, arguable, or otherwise distinctively notable.
CHAPTER 1: HOW TO BUILD A HUMAN
Altogether, according to RSC calculations: The information on the cost of building a replica Benedict Cumberbatch was supplied by Karen Ogilvie of the Royal Society of Chemistry, London.
We need, for instance, just 20 atoms: Emsley, Nature’s Building Blocks, 4.
We now know that selenium makes two vital enzymes: Ibid., 379–80.
you can irremediably poison your liver: Scientific American, July 2015, 31.
in 2012 Nova, the long-running science program on PBS: “Hunting the Elements,” Nova, April 4, 2012.
Well, you blink fourteen thousand times a day: McNeill, Face, 27.
The length of all your blood vessels: West, Scale, 152.
if you formed all the DNA in your body: Pollack, Signs of Life, 19.
You would need twenty billion strands of DNA: Ibid.
Its chemical name is 189,819 letters long: Ball, Stories of the Invisible, 48.
Nobody knows how many types of proteins: Challoner, Cell, 38.
All humans share 99.9 percent of their DNA: Nature, June 26, 2014, 463.
My DNA and your DNA will differ: Arney, Herding Hemingway’s Cats, 184.
about a hundred personal mutations: New Scientist, Sept. 15, 2012, 30–33.
One particular short sequence, called an Alu element: Mukherjee, Gene, 322; Ben-Barak, Invisible Kingdom, 174.
Five out of every six smokers: Nature, March 24, 2011, S2.
between one and five of your cells turns cancerous: Samuel Cheshier, neurosurgeon and Stanford professor, quoted on Naked Scientist, podcast, March 21, 2017.
Our bodies are a universe of 37.2 trillion cells: “An Estimation of the Number of Cells in the Human Body,” Annals of Human Biology, Nov.—Dec. 2013.
There are thousands of things that can kill us: New Yorker, April 7, 2014, 38–39.
We undertake every part of the process: Hafer, Not-So-Intelligent Designer, 132.
CHAPTER 2: THE OUTSIDE: SKIN AND HAIR
“Our seams don’t burst”: Jablonski interview, State College, Pa., Feb. 29, 2016.
We shed skin copiously, almost carelessly: Andrews, Life That Lives on Man, 31.
We each trail behind us: Ibid., 166.
acne, a word of very uncertain derivation: Oxford English Dictionary.
They detect light touch: Ackerman, Natural History of the Senses, 83.
if you sink a spade into gravel or sand: Linden, Touch, 46.
Curiously, we don’t have any receptors for wetness: “The Magic of Touch,” The Uncommon Senses, BBC Radio 4, March 27, 2017.
Women are much better than men at tactile sensitivity: Linden, Touch, 73.
skin gets its color from a variety of pigments: Jablonski interview.
Its production slows dramatically as we age: Challoner, Cell, 170.
“Melanin is a superb natural sunscreen”: Jablonski interview.
Melanin often responds to sunlight: Jablonski, Living Color, 14.
The red of sunburn: Jablonski, Skin, 17.
The formal name for sunburn is erythema: Smith, Body, 410.
The process is known as melasma: Jablonski, Skin, 90.
some 50 percent of people globally: Journal of Pharmacology and Pharmacotherapeutics, April/June 2012; New Scientist, Aug. 9, 2014, 34–37.
As people evolved lighter skin: University College London press release, “Natural Selection Has Altered the Appearance of Europeans over the Past 5000 Years,” March 11, 2014.
Skin color has been changing: Jablonski, Living Color, 24.
Indigenous populations in South America: Jablonski, Skin, 91.
Rather harder to explain have been the KhoeSan people: “Rapid Evolution of a Skin-Lightening Allele in Southern African KhoeSan,” Proceedings of the National Academy of Sciences, Dec. 26, 2018.
Using DNA analysis: “First Modern Britons Had ‘Dark to Black’ Skin,” Guardian, Feb. 7, 2018.
suggested that the DNA used in the analysis: New Scientist, March 3, 2018, 12.
We are actually as hairy as our cousins the apes: Jablonski, Skin, 19.
Altogether we are estimated to have five million hairs: Linden, Touch, 216.
it provides warmth, cushioning, and camouflage: “The Naked Truth,” Scientific American, Feb. 2010.
In furry mammals, it adds a useful layer: Ashcroft, Life at the Extremes, 157.
Horripilation also makes mammalian hair stand up: Baylor University Medical Center Proceedings, July 2012, 305.
genetic studies that dark pigmentation: “Why Are Humans So Hairy?,” New Scientist, Oct. 17, 2017.
“because it increases the thickness of the space”: Jablonski interview.
humans don’t seem to have pheromones: “Do Human Pheromones Actually Exist?,” Science News, March 7, 2017.
secondary hair is for display: Bainbridge, Teenagers, 44–45.
We each grow about twenty-five feet of hair: The Curious Cases of Rutherford and Fry, podcast, BBC Radio 4, Aug. 22, 2016.
The system introduced the concept of the mug shot: Cole, Suspect Identities, 49.
The uniqueness of fingerprints was first established: Smith, Body, 409.
They are assumed to aid in gripping: Linden, Touch, 37.
why our fingers wrinkle when we have long baths: “Why Do We Get Prune Fingers?,” Smithsonian.com, Aug. 6, 2015.
