Verwandte Artikel zu Ageless: The New Science of Getting Older Without Getting...

Ageless: The New Science of Getting Older Without Getting Old - Softcover

Steele, Andrew

 
9780593214794: Ageless: The New Science of Getting Older Without Getting Old
Softcover
ISBN 10: 059321479X ISBN 13: 9780593214794
Verlag: RANDOM HOUSE LARGE PRINT, 2020

Inhaltsangabe

“A fascinating look at how scientists are working to help doctors treat the aging process itself, helping us all to lead longer, healthier lives.” —Sanjay Gupta, MD

Aging—not cancer, not heart disease—is the underlying cause of most human death and suffering. The same cascade of biological changes that renders us wrinkled and gray also opens the door to dementia and disease. We work furiously to conquer each individual disease, but we never think to ask: Is aging itself necessary? Nature tells us it is not: there are tortoises and salamanders who are spry into old age and whose risk of dying is the same no matter how old they are, a phenomenon known as “biological immortality.” In Ageless, Andrew Steelecharts the astounding progress science has made in recent years to secure the same for humans: to help us become old without getting frail, to live longer without ill health or disease.

Die Inhaltsangabe kann sich auf eine andere Ausgabe dieses Titels beziehen.

Über die Autorin bzw. den Autor

After obtaining a PhD in physics from the University of Oxford, Andrew Steele decided that aging was the most important scientific challenge of our time and switched fields to computational biology. He worked at the Francis Crick Institute, using machine learning to decode our DNA and predict heart attacks using patients’ medical records. He is now a full-time science writer and presenter based in London. He has appeared on the BBC and on Discovery, Inc.’s Science Channel.

Auszug. © Genehmigter Nachdruck. Alle Rechte vorbehalten.

1

The Age of Aging

Cast your mind back 25,000 years. It’s late on a warm spring afternoon in what we now call southern France, and you’re gathering firewood a short way from your camp. The men are out hunting, carrying spears and seeking out game like deer and bison. You and your fellow nomads look pretty much like modern humans, but life is very different—not least because of the ever-­present risk that it will end suddenly.

At 28 years old you’re doing quite well for a prehistoric woman. There are risks everywhere. A tiny scratch could get infected and kill you; you could meet a sudden end in an accident or animal attack; or other prehistoric humans, hungry and desperate, could murder you in a fight. Most tragic of all, though, out of the five children you’ve given birth to, two have died—one shortly after birth from what we’d now understand to be a serious fever, and another aged three who you buried just a month ago. Prehistory is a dangerous place to live, and death seems to strike at random, often without obvious cause. There’s no understanding of germs or birth defects—perhaps you blame capricious, vengeful gods or spirits in an attempt to make sense of it all.

It’s hard for us to work out exactly how long prehistoric humans lived, not least because prehistory is defined as the period prior to written records. There were no birth certificates or insurance companies compiling detailed mortality tables. However, surveys of bones at a handful of archaeological sites, plus extrapolation from modern hunter–gatherer societies, give us some idea—and it’s at once better and worse than you might expect.

First, the bad news: life expectancy was poor, probably somewhere between 30 and 35 years. Statistically speaking, a lot of you reading this would already be dead. However, life expectancy is a number which can obscure as much as it reveals. This is because it’s an average and comes with all the attendant statistical pitfalls. The main reason that it was so strikingly low in prehistory was the appalling rate of infant and child mortality. Infections in the first few years of life struck down many, many babies and children. You probably had only a 60 percent chance of making it to 15 years old—barely better than tossing a coin. This huge number of deaths at young ages drags down the average age at death significantly.

However, if your coin came up heads and you made it to your late teens, you could expect to live another 35 or 40 years, taking you comfortably into your fifties. This “remaining life expectancy” is itself an average, so it’s quite likely that a few ancient humans did make it into their sixties or seventies—what we, in modern times, would start to call “old age.” A headline 35-year life expectancy both masks the terrible toll of childhood deaths and underplays how long the oldest early humans lived. Such is the challenge of summarizing a complex phenomenon like human lifespan with a single number.

This was the story for tens of thousands of years: eye-watering levels of child mortality held overall life expectancy down; most who made it to adulthood lived decent but not exceptionally long lives. For millennia, death was an omnipresent feature of human life, often rapid and without warning. Those who escaped the capricious clutches of infectious disease, injury or bad luck were greeted by an inexplicable state of decline which we’d now recognize as aging: a gradual loss of faculties in a world where fitness, keen senses and mental acuity could be the difference between eating and being eaten.

It can be tempting to think of prehistoric humans as primitive, but their brains were actually very similar to our own; it seems likely that this constant, senseless loss would take its toll. While we can only speculate, there are sites where human or pre-human remains are found together, suggesting some kind of deliberate disposal of the dead. There’s an ongoing debate about when exactly funeral rituals arose—many, of course, would leave no trace which could survive the intervening millennia. But, if these sites are what they appear, funeral behavior could date back tens or even hundreds of thousands of years, to a time before our species, Homo sapiens, when our hominin ancestors walked, and aged, upon the Earth. As we transition into recorded history, our preoccupation with death is hard to deny: increasingly extravagant structures culminating in the pyramids of ancient Egypt formed the engineering pinnacle of increasingly rich mythologies surrounding life and its end.

Given this, it’s perhaps not surprising that some of the earliest philosophers grappled with aging and death. In ancient Greece, Socrates and Epicurus were unworried by dying, believing that it would be like eternal dreamless sleep. Plato was similarly sanguine, but for different reasons: he believed that our immortal souls would go on existing even after our bodies had ceased to. Aristotle was more concerned by death, and arguably the first philosopher to make a serious attempt to explain aging scientifically in 350 bce. His central thesis was that it was a process by which humans and animals dry out; as you will note from its absence in the rest of this book, sadly his theory hasn’t stood the test of time.

Even as schools of philosophy, religions and empires rose and fell, surprisingly little changed about lifespans for thousands of years. A family moving to London in 1800, looking for work as England industrialized, would have a surprisingly similar tale to tell as their nomadic ancestors, statistically at least. The exact causes of death were quite different—fewer hunting accidents, more factory accidents, and a different spectrum of infectious diseases at home in densely populated urban centers rather than small, nomadic groups—but the result was much the same: high birth rates, high death rates. By this time in history we do finally have some actual data to go on—the two countries whose records stretch back the furthest are the UK and Sweden, and both show an overall life expectancy somewhere around forty years in the early nineteenth century.

As the 1800s got into full swing, things finally began to change. Slowly, between 1830 and 1850, graphs of life expectancy start to pull up. If we take the leading country in the world at any given time, which we can regard as the state of the art in population health for any given moment in history, a very striking picture emerges. The maximum global life expectancy has increased by three months every year since 1840, with clockwork regularity. Even better, the trend shows no sign of abating. Predicting the future is always hard, but you could do worse than to extrapolate this trend of nearly two centuries onwards into it. That means (if you’re middle-aged or younger), for every year you stay alive your expected date of death recedes a few months into the future. Alternatively, for every day you survive, you gain another six hours—meaning that a good night’s sleep isn’t really time wasted, as you’re getting most of it back thanks to rising life expectancy.

The cumulative effect of this incredible progress is that lives are now twice as long on average as they were in the early 1800s—life expectancy has gone from 40 years back then, to over 80 in the rich world today. It’s easy to be glib about this meteoric rise because it’s so familiar, so take a moment and transpose those dry numbers onto your own life. At 40, you’d be statistically dead in 1800; now, you’ve got as much life again still in front of you. A 20-year-old today has...

„Über diesen Titel“ kann sich auf eine andere Ausgabe dieses Titels beziehen.

Verlag
RANDOM HOUSE LARGE PRINT
Erscheinungsdatum
2020
Sprache
Englisch
ISBN 10 
059321479X
ISBN 13 
9780593214794
Einband
Taschenbuch
Anzahl der Seiten
485
Kontakt zum Hersteller
Harder
https://www.edel.com

Neum�hlen 17
Hamburg
Hamburg
22763
Deutschland