Some evolutionary biologists say that after we pass reproductive age, nature, like a cat who’s been fed, is done with us. The bodily systems that thrived and repaired themselves to ensure that we pass on healthy genes cease to function well and leave us to slink to the finish line the best we can. Neuroscientist Daniel Levitin, author of this year’s Successful Aging, says “that’s not an unreasonable interpretation,” but he doesn’t settle for the view that aging after 40 is a long and listless mosey to the grave.
Levitin, 62, emeritus professor of psychology and neuroscience at McGill University, has lit up readers’ minds with his books on the joys of music, This Is Your Brain on Music and The World in Six Songs. But unlike an aging rocker playing his hits on an oldies tour, Levitin has remained fresh as a writer on the brain, exploring, in The Organized Mind, how to navigate our way through information overload to sane shores. In Successful Aging he details the effects of aging on this too solid flesh, from cell function to motor actions to sleep patterns, and prescribes ways of living to mute the insults of growing old.
Levitin nicely articulated his insights into better aging and living in our interview. After I transcribed our lively talk, I decided to step out of the picture and present his views on their own, under short subheads.
How We Age
We all age at different rates due to our history of exposure to environmental toxins and other stressors, both physical and psychological. That could include a history of a disease like diabetes, or whether you’ve been hit in the head repeatedly. We all know about people who are 50 and whose bodies are giving out, and people who are 90 and going strong. And the brain is a part of the body. Some people are able to enjoy long, sustained periods of cellular housekeeping and repair and others are not. To a neuroscientist, stress is a biological process. It’s not just road rage or being frustrated at work. Stress is a chemical response to things that happen to you and actually impairs the body’s ability to repair itself.
Why We Age
The question of why we age has produced a lot of false answers, such as, “We age because if we didn’t we would overpopulate the earth.” But evolution doesn’t know about overpopulation, so that doesn’t make sense. Or “We age so we don’t take for granted the time that we have.” But that’s nonsensical as well. These might be religious or philosophical notions, but they’re not scientific. We age because there’s been no evolutionary pressure to keep our bodies alive for a long time. I don’t know why that is and I don’t think anybody does.
Successful aging is being able to continue to take pleasure from activities that have historically brought you pleasure.
When We Age
Aging begins with conception, fertilization, and cell division. You age in the womb, you age on the day you’re born, you continue to age. After reproductive age, it’s not that nature is done with us, although that’s not an unreasonable interpretation. But the whole idea of Darwinian theory, of descent with modification, random mutation, and natural selection, is that whatever shows up in your genome gets passed to the next generation. It influences the next generation and the generation after that and so on.
Suppose there were people who had this super genome that allowed them to live to be 100. Let’s take women because the reproductive cut off for women is pretty well defined. If a woman has some genetic modification or mutation that allows her to live to be a 100, that isn’t going to show up in the reproductive genome at age 40 necessarily. It will get passed on, but there’s no selection force. That is, no evolutionary mechanism that causes it to become more common in the population.
The traits that allow you to attract a mate have to do with your health and mental and physical stability at age 20, 30, and 40. If there’s something that could be happening to you at age 90, there’s no way for that to be selected by evolution because you are likely beyond reproductive age. There’s no evolutionary pressure for it. That’s been the hardline that Alison Gopnik and others have talked about with the “grandparents syndrome.” In Orca whales and humans, grandparents play a role in raising the grandkids, and so although a grandparent is only passing on a quarter of their genes, to a grandchild as opposed to half their genes to their own children. They are strengthening the viability of that child to go on and reproduce by nurturing it. In other words, the evolutionary pressure to pass on genes might be fulfilled in part by grandparents who have a gene for nurturing behavior that makes both their children and grandchildren more successful in life.
How We Die
At some point, unless we get hit by a bus, we’re all going to die of disease. Which is a way of saying that our ability to repair our bodies and cells won’t be able to keep up with the accumulated damage that life has brought to them. The system just doesn’t function as efficiently as we get older. And at some point it catches up to us and the body shuts down. I mean, nobody just dies, they die of something. A friend of mine’s mother just died. She had cancer and doctors gave her a few months to live. Then she got an E. coli infection because her immune system was compromised trying to fight the cancer. And so then they give her antibiotics. It got rid of the E. coli but then metabolizing the antibiotic was tough on her liver, and her liver wasn’t able to keep up with the cleansing procedures necessary to make it function well, and so she ended up dying about a week later of liver failure. The biggest risk factor for death is age.
Successful aging is being able to continue to take pleasure from activities that have historically brought you pleasure, and being able to find new things that provide pleasure. It’s being able to engage with life, with friends and relationships, and being able to make a contribution to the world—whether it’s the way the Dalai Lama and Jane Goodall are doing it, or just the world of your own family.
People who have an upbeat personality are more inclined to engage with other people. And other people are more inclined to want to engage with them. Nobody wants to be around a perpetual sourpuss. And social connections are vitally important to life satisfaction and successful aging, and in fact loneliness has been associated with a greatly increased risk of premature death. It compromises the immune system. Upbeat people tend to explore the environment more, which means they’re going to be more apt to learn new things and stay mentally challenged. They don’t get into despair. An optimistic person will more likely take steps to safeguard themselves because they think those steps are going to amount to something.
People who have a personality that’s more generous have brains that are physically different.
The neurochemical serotonin is responsible for mood regulation, and it’s also a precursor to immune system function. So if you’re in a good mood, and your serotonin levels are healthy, that’s going to produce T cells and natural killer cells, which are like the James Bond of the immune system. They handle the most difficult cases. Many of us have cancerous tumors growing in us all the time, but our immune system gets rid of them. We just don’t know about it. That’s how the immune system is supposed to work. When the immune system is compromised, or the cancer evolves some kind of special mutation that makes them resistant to our immune system, you can end up with a malignancy. But being upbeat, being sociable, being engaged with life tends to increase serotonin. And being stressed, which releases cortisol and adrenaline, for evolutionary reasons, turns your immune system off. It also turns off higher cognitive thought, digestion, and libido. In the short term, if you’re trying to escape from a tiger, it’s OK to shut down those systems. But you don’t want them chronically shut down.
Be optimistic but realistic. You get a big ugly black growth on your arm and you think it couldn’t possibly be cancer and so you don’t have it checked. That’s too much optimism. False hope is tricky. If you’re convinced you’re going to die, and it sends you into a mental funk, depression and stress, that shuts down your immune system. If you’re optimistic and think you can fight this, you may be able to tilt the balance. Somebody could say, “I’ve got a 20 percent chance of living with this for another five years. Screw this, I’m just going to make out my will and sit on the couch and eat bonbons until I go.” But the other person would say, “20 percent? Maybe I can increase that to 30 if I do these things.” And that’s worth doing. You want to avoid the extremes of gullible optimism and fatalistic pessimism.
We shouldn’t fear death. We need to prepare for it. If you’re afraid of a traffic accident, you still have to drive. You wear your seatbelt, you make sure the car is in good shape, the tires are inflated. Employ the same kind of conscientiousness you do before a long road trip to your own aging process. Follow healthy practices—a good diet, exercise, and good sleep hygiene. Make sure you have a doctor you trust, one you can communicate frankly with, one who sees you as a whole person and can help you to minimize the risk that something bad will happen.
Stress actually impairs the body’s ability to repair itself.
Take a Chance
My thesis is that you can tilt the balance with positive psychology and lifestyle changes. But you can’t guarantee you’re going to live forever. To some extent, whether you’re going to get cancer is out of your conscious or direct control. But I have a friend who’s beat cancer twice, and in both cases the doctors gave him just a year to live. That kind of thing is underappreciated. If the doctor says you’ve got metastasized lymphoma and six months to live, that’s an average across a whole lot of people who are not you. Some people are going to die tomorrow, and some people are going to live another 40 years. In the aggregate, you’ve got six months to live. Whether you’re in the category of people who die tomorrow or live another 40 years, to some extent that’s not under your control or volition. It’s just your own particular body, with its own particular way of handling things. But there is a small percentage of people whose bodies will respond to efforts to beat cancer. Not in every case, but in some cases. And I think most people would say it’s worth a shot.
There are certainly scammers out there who want to separate you from your money and pedal you all kinds of things that don’t work. Aging supplements that don’t work are a billion-dollar industry. To me, pseudoscience is somebody who uses the words of science in a superficial way to bamboozle people who don’t understand the science, which is most of us. They start talking about stuff like quantum energy fields, or about profusion of blood in Spect images. And some of this is jive, it’s true.
But your attitude and personality do affect your brain. People who have a personality that’s more generous, people who experience compassion—even if they didn’t come by it naturally, but had to learn to do it, or had to meditate, or join a religion—have brains that are physically different. Your brain changes in response to your experiences but not just your experiences. Your brain changes in response to how you respond to those experiences. If you greet the world with compassion and gratitude, big parts of your brain that have a lot to do with immune system function and cellular repair are strengthened.
It’s easy to draw out the connection between successful aging and conscientiousness. Conscientious kids don’t cross against the light and get hit by a bus. Conscientious adults don’t end up in prison because they follow rules. They don’t end up burning through all their money because they set a little bit aside. They go see the doctor when something is wrong. Conscientiousness is huge, and it’s unevenly distributed through the population, as are all personality traits. The good news is that even if you don’t have a lot of it, or you have too much of it and you’re obsessive-compulsive, you can change. And you can change at any age. You’re never too old to change.
Kevin Berger is the editor of Nautilus.
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