The Longevity Book: Live stronger. Live better. The art of ageing well.. Cameron Diaz

that little voice in my head says “Stop! Why? Enough!” I say, “Because I like it. Because it keeps me strong.” That is the legacy my grandmother left me, and I thank her for it each and every day.

      My grandfather, although he lived in the same house with my grandmother, had a very different lifestyle than she did. His job required him to sit in an office, he smoked and he chewed tobacco, and he enjoyed red meat more than his vegetables. When I was eight years old, he had a heart attack and passed away. He was only sixty-three. Meanwhile, my grandmother lived to be nearly ninety. She stayed vital into her seventies. Hauling feed, along with all of her other regular chores, kept her strong and resilient.

      But even hard work cannot always protect us from illness. At seventy-three, my grandmother was diagnosed with breast cancer, which is now considered to be an age-related disease. She also developed an irregular heartbeat. So she underwent two major surgeries to save her life – she had a mastectomy and she had a pacemaker implanted. During her recovery she came to stay with us, and I spent that summer making meals, helping her bathe, and reading to her as she drifted off to sleep. She had a bell that she would ring in the morning, and I would come and take her to use the bathroom. For the first time in her life she was relieved of her strenuous chores and her day-to-day responsibilities – and she liked having her family close by, helping her, caring for her.

      When she got better, she went back to her active lifestyle, gardening and working around the house. But she was getting older and getting tired. She didn’t have the same energy that she’d had abundantly before her battle with cancer. And so, after a while, she decided that she had worked hard enough. She didn’t want to take care of the animals and the garden anymore. She wanted a less strenuous life – and so my mum and dad asked her to move in with us.

      At first she remained active, walking around the house and hanging out in the kitchen. But as time went by she began to rely more and more on our caretaking, and I watched her go from functioning mostly on her own to relying on me to hold her up as she scuffled with her walker. She went from sitting with the family in the living room to spending most of her day lying down and asking everyone to come visit her in her bedroom. She stopped eating her meals at the table and requested to have them in bed. As her effort declined, so did her health. I could understand how at her age she might want a rest from her backbreaking chores, but it was hard and confusing for me to watch her change. She was never the same again.

      I was just a kid, but her changes imprinted on me how fragile even the strongest person could become. I saw how important it is to work as hard as we can, for as long as we can, if we want to age with strength.

      WHERE DID YOU LEARN ABOUT AGEING?

      I witnessed different kinds of ageing when I was a kid, and it taught me a lot about what I might expect for myself. Where did your first ideas about ageing come from? Many of us learned about what ageing looks like by watching our family members grow older. Were your grandparents healthy and active, or did they always seem old and infirm? How about your parents? The attitudes we absorb about what it means to age and what life is like for the aged will affect our own ageing process.

      Your birthday does not determine how long or well you will live. You may share the same birth year as someone else, or even the same birth date and birth mother, but the way that you live will affect the way that you age. While there are broad age-related changes that apply to everyone, for an individual, biological age (how healthy you are on the inside) is a more important indicator of health than chronological age (the number of years you’ve been on this planet). The ageing of our cells is the true measure of how old we are.

      Many different factors influence the way you age. There’s the genetic component, of course, which we are reminded of every time we give our family medical history at the GP surgery. But genes aren’t everything. While some research ties longevity to the genes we inherit from our parents, our choices, our environment, and our attitude have just as powerful an impact on how healthfully and long we live. How old we truly are – in a biological sense – is a combination of these factors.

      My grandmother’s habit of hauling chicken feed on hot summer days at the age of seventy is a good example of how the number of years we have lived and the level of health and independence we enjoy do not always correlate. Each of my grandparents aged in a way that was purely of them, not only genetically but also an extension of their personalities and how they lived their lives. When I was growing up, I was aware that my grandmother was seven years older than my grandfather. But now I understand that biologically, deep within her cells, she was probably a lot younger than her chronological age.

      Nobody can resist the pull of time forever, but the longer we are able to find the energy and the reserves to keep pushing ourselves, to believe that ageing with strength is possible, the stronger and more self-reliant we are likely to remain.

      AGEING IS PERSONAL

      Nature gives you the genes you have at birth. As an adult, the environment you live in and the lifestyle choices you make help determine how you age and how you feel. Since where you live and how you live is personal to you as an individual, so is the way that you age. That’s part of why the study of ageing is so complex: there is no one-size-fits-all answer. You start out as a cluster of cells that develops in response to the genes that are coded deep within your DNA, which are also known as your genotype. Your genotype is what you inherited from both of your parents, basically the blueprint that nature has used to create and build you. When infants are born, they are immediately weighed and measured. This is a useful marker for health, because babies can be compared by height and weight. But by the time we are toddlers, our environments have already begun to affect our development as much as our genes.

      Even in our earliest years, our environments influence our health. Growing up in a household that is very stressful, for example, will affect your genes differently than if you are raised in a home that is calm and secure. Alexandra Crosswell, a research scientist at the University of California, San Francisco, whom we saw give a rousing lecture about her work, has been studying a group of breast-cancer patients to investigate the ways exposure to stress during our childhood years can affect our health as adults. She found that participants who had experienced abuse, neglect, or chaos within their home as children showed biomarkers for inflammation later in life that are linked to negative outcomes for health and well-being.

      Life has a real effect on our health. Stress and trauma and smoking have an effect; love and safety and eating green vegetables have an effect. But these factors don’t just have a short-term impact on our well-being; as Dr Crosswell’s study suggests, they can also have a very powerful, long-term influence. How is this possible? Because your lifestyle – the experiences you have, the places you live, the choices you make – can actually alter the way your genes are expressed.

      Some genes are like light switches that can be flicked on or off by experience. Good nutrition, fitness, and low levels of stress may help flick off some of your genetic predispositions to disease, while smoking, eating poorly, and being sedentary may activate on your genes for disease. And the genes that have become altered as a result of your lifestyle can actually be passed down to the next generation. That means that the DNA each one of us receives from our parents is influenced by the lifestyle of not only our parents, but also our grandparents and our great-grandparents and our great-great-grandparents. The study of this biological phenomenon is called epigenetics. A relatively new branch of the field of genetics, epigenetics suggests that the effects of life on our genes can be passed down like family heirlooms.

      My grandmother’s active nature affected my attitude about ageing. But the effects of her choices on my health may be even deeper than attitude. If she was especially active when she was young, then those genes could have been passed on to my mother, and to me.