Josh Mitteldorf - Cracking the Aging Code: The New Science of Growing Old - And What It Means for Staying Young

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Go over the heads of the scientists, she said, take your case directly to the people. Thats what Darwin did!

To my mother, Harriet Mitteldorf (1922)

JJM

Tis not that Dying hurts us so
Tis Livinghurts us more
But Dyingis a different way
A Kind Behind the Door

EMILY DICKINSON

Now flip, flop, and fly, I dont care if I die.

BIG JOE TURNER,
A KANSAS CITY BLUES CROONER
AND FOUNDER OF ROCK AND ROLL

Over my dead body.

GEORGE S. KAUFMAN,
SUGGESTING HIS EPITAPH

What Is Aging?

Scientists sometimes use the word senescence . The common meaning is a deterioration in many body functions that comes with age. Sometimes we will use the demographers definition: an increased risk of death with passing time.

It is a common belief that aging is inevitable and universal. Not on your life!

During the twentieth century, medical technology took enormous strides toward the conquest of infectious disease and recovery from trauma. With hygiene and sanitation, then antibiotics in the 1930s and an ever-expanding arsenal of vaccines, many plagues of the past have been vanquished: polio, syphilis, whooping cough, diphtheria, and cholera were once feared as a death sentence, and now they are footnotes in the mortality statistics. The diseases that remain are all associated with aging; diabetes, arthritis, and osteoporosis are growing, and the Big Three killers are cardiovascular disease, cancer, and Alzheimers. Tens of billions of dollars have been spent on medical research over several decades trying to conquer these diseases with the same approach that succeeded so well for infectious disease.

That approach has been to work with the body, to stimulate the bodys growth and inborn strength, to buttress its natural defenses. Even the reductionist tradition of Western, allopathic medicine has been influenced by the philosophy of natural medicine, working with the body instead of attempting to overpower it with technology or drugs. But what the doctors do not yet realize is that they are working with a suicidal patient.

Suicide Genes

Man overboard!

You run to the railing and throw him a lifeline. If only you can get the buoy within his reach, you might pull him back to safety

Good toss! The life preserver is right in front of him, but he is not taking it. Is he just too weak? Has he lost the will to live? You call to him. Go away, he answers. Leave me alone! And now your understanding of his situation is changed.

He didnt fall off the boathe flung himself into the sea. To save a man from drowning is one thing; to dissuade him from suicide will require a different approach. In the immediacy of the crisis, you might take advantage of his exhaustion, jump in the water, overpower him, and carry him forcibly to safety. But next week, he might make another attempt. To help this man, you will have to get to know him, learn what is important to him, understand why he wants to kill himself, and convince him to choose life.

* * *

Doctors today are trying to help a body that does not want to be helped. Efforts to restore the bodys natural balance wont work, because as we age, the bodys natural metabolism is bent on self-destruction. Attempts to bolster the bodys natural defenses are doomed to failure because the natural defenses are slowly being shut down with age.

Progress can be made against the Big Three diseases, and aging itself can be abated, but a different approach is required. We must be willing not just to assist the body but to coax, cajole, and even fight with it when appropriate. We must learn more about hormones and the signaling language that regulates metabolism. We must whisper the word youth in the bodys own native language of biochemistry, a language as yet still somewhat foreign to us. But this is the language in which the entire life plan is spelled out, from development in the womb to aging and death.

Selfish Genes

The central idea of this book is that aging is built into our bodies. Aging doesnt just happen but is regulated and controlled by our genes. Our self-destruction is scheduled as much as is our development in childhood or our sexual development at puberty. Growth, puberty, and aging all unfold on a schedule programmed into the regulatory segments of our DNA.

But to an evolutionist, these things are not the same at all. A strong body helps us to survive and preserve ourselves. Sexual development is necessary for reproduction. These things are good for us, good for the prospects of our genes. They help our genes to be passed along, to prevail, and to spread in succeeding generations. This fits well with the idea of natural selection, the fundamental premise of Darwinian evolution. It is easy to understand how genes for growth and sexual development evolved. They are selfish genes, because they help the body, their vehicle, and so they help themselves.

But aging is about weakening and dying. It cannot be good for the body. Genes may cause aging, but aging cannot promote the prospects of those genes; quite the contrary, aging ends the careers of the very genes that cause it. This does not make sense from the prevailing evolutionary perspective. Why would selfish genes kill their bodies? But in fact multiple lines of evidence suggest that is exactly what they are doing. As we get older, our genes turn against us, killing healthy nerve cells and muscle cells, permitting the thymus gland to wither away, which undermines our immune system. We consider this self-destruction normal, but in fact, it doesnt apply to all species. There are a few animals and many plants that do not age. And although selfish gene theory cannot explain why our bodies do this, another theorythe Demographic Theory described in chapter 8does. The self-destruction we take for granted is in fact under evolutionary control. These evolutionary suicidal tendencies, while they do not make us as individuals live long and prosper, turn out to have a vital evolutionary function.

These suicide genes are the opposite of selfish genes. In the course of evolution, genes for aging must have fought an uphill battle against natural selection. How could aging have evolved?

This is a question that has been asked over and over since Darwin first skirted the issue 150 years ago. In fact, there was no mention at all of life span or aging in the first edition of On the Origin of Species (1859). Skeptics confronted him with the great range of life spans in nature. Why have life spans not evolved ever longer? Isnt that what we should expect from your theory? Darwins answer in later editions was uncharacteristically vague and unconvincing. Although many volumes and thousands of articles have been written on the subject ever since, there are really only three kinds of answers.

Three Evolutionary Stories About Aging

Answer number one is that there really is no aging in nature. Animals in the wild do not live long enough to die of old age, because they die of other things first. Its a highly competitive world out there, red in tooth and claw. Organisms are ever at risk from predators, accidents, and starvation. We are aware of aging when we look at domesticated animals protected from their natural enemies, and of course civilization has afforded humans a safety that is completely uncharacteristic of our evolutionary history. Aging is an artifact of protected environments, and in the natural world where evolution runs its course, aging doesnt existso there is nothing to explain.