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

lot of people hate going to the doctor, and I get it. Hanging out in a waiting room on your lunch hour or having blood drawn when you’re running late for another appointment is not exactly fun. But I take going to the doctor very seriously. When I’m sick, I make an appointment. And when I’m healthy, I make appointments, so that I can avoid getting sick for as long as possible. I want to understand where my health is now so that I have a framework for comparison for later. I want to use medicine as a preventative tool for my health as I age.

      And researchers are discovering that this habit of mine might actually be tied to female longevity. Women are more likely to visit the GP than men and this may help us to live longer. So do the other healthy choices that, as a group, women make more than men do, like not smoking. Fewer women than men smoke, which cuts our risk profile for numerous diseases. Men also drink more than women do. Women are more careful about their nutrition, and taking care of food needs helps bolster strength and longevity. And women are less likely to take risks. Fewer risks equals fewer injuries, which equals greater health: unintentional injury is number three on the Centers for Disease Control and Prevention’s mortality charts for men, and number six for women. Women also value friendship, love, and connection. We are social beings who invest in our families and in our communities and in our relationships. All these choices contribute to a longer life.

      But female longevity isn’t just about our choices. Among primates like chimpanzees, females live longer too, and monkeys don’t make doctor’s appointments. So why do females enjoy a longer life span? Some scientists are looking for answers that are rooted deep within the genetic coding of our cells. The cells of men and the cells of women are not the same, and what makes your cells unique affects everything about you – including how long you live.

      THE OLDEST WOMAN IN THE WORLD

      Today, life expectancy is twice what it used to be, but it may still be forty years shy of the maximum human life span, which most scientists believe to be about 120 years old.

      They base that opinion on people like Jeanne Calment, the oldest woman who ever lived. Jeanne was born in France in 1875 and passed away in 1997. When she was a year old, Alexander Graham Bell invented the telephone. When she was thirteen, she met Vincent van Gogh. When she was eighteen, the Wright brothers flew for the first time. She lived through two world wars, saw infections thwarted by medicine, and witnessed the development of the Internet and contemporary medical technologies.

      When she was ninety, a lawyer who was not yet fifty offered to pay her every year if he could take over her home when she died. She agreed. He died at seventy-seven, and Jeanne kept on going. She lived by herself until she passed away at the age of 122.

      WHAT DOES IT MEAN TO BE BIOLOGICALLY FEMALE?

      You are a lady with millions of microscopic lady cells. Your female cells are special – the genetic information contained in each and every one of them is what makes your body biologically distinct from that of a man. Your female cells have unique characteristics, and so do the organs they make up, because female organs are sized and shaped differently than male organs.

      For example, the female heart has a distinct architecture. Our heart is smaller than a man’s, with thin vessels arranged in a lacy pattern instead of the thicker tubes that connect a male heart to his cardiovascular system. Cholesterol plaques can settle throughout a woman’s arteries, instead of in a more obvious clump, as tends to happen in men’s hearts, making it more challenging to detect heart disease in women. That is why women experience heart attack symptoms differently than men do, and why they need different care at the hospital during and afterwards. Women are far more likely than men to receive an incorrect diagnosis about heart attack symptoms despite the fact that more women than men die of cardiovascular disease every year in the US and the UK.

      Our hearts also beat in a distinct rhythm; any disruption of that rhythm results in an irregular heartbeat, called an arrhythmia, which can range in severity from mildly disruptive to life threatening. In addition, some medications and defibrillators – which have primarily been tested on men – have been shown to cause potentially fatal complications in women.

      Women’s unique biology also translates into unique risk factors for disease. For example, women are more likely than men to develop depression, eating disorders, and anxiety disorders like post-traumatic stress disorder. Mental health issues are, in turn, a risk factor for a variety of other diseases. A twelve-year study of more than 10,000 women in Australia aged 47–52 showed that middle-aged women who were depressed have twice the risk of having a stroke compared to women who are not depressed.

      But until the past few decades, nobody was talking about female cells, and it’s taken some time for the medical and scientific communities to realize just how important it is to consider the sex of our cells when it comes to healthcare. Today, with an improved understanding of how sex-specific biology affects research, diagnostics, and medical treatment, women are getting better care.

      HOW DO CELLS GET A SEX?

      Healthy people have forty-six chromosomes in each of their cells. Two of your forty-six chromosomes determine sex. The rest, the autosomes, determine pretty much everything else about you. Sex chromosomes only come in two varieties: X and Y. Women are XX and men are XY. The X chromosome is much larger than the Y chromosome, because it is a powerhouse: not only does it determine sex, it also contains additional genes and thus additional information. The Y chromosome is smaller and carries less information.

      Your sex is determined by your father. When a sperm, which has twenty-three chromosomes, twenty-two autosomes, and one sex chromosome, collides with an egg, which has twenty-three chromosomes, twenty-two autosomes and one sex chromosome, fertilization takes place. The result is a complete human cell – called a zygote.

      Since all of a woman’s cells have an XX, her eggs can only have an X. Since men have an XY, their sperm can contain either an X or a Y. It’s a toss-up. Will a fertilized egg become a female or a male? It’s all about the sex chromosome carried by the sperm.

      If you are a woman, the sperm that made you carried an X chromosome. As the female zygote divided, all the cells it made were female, and thus, so are you. A zygote divides and replicates and divides and replicates and divides and replicates. And after all that replication, you’ve got a cluster of female embryonic stem cells that will eventually keep dividing to become heart cells and liver cells and skin cells and blood cells and brain cells. And all those resultant organs will be female organs made up of female cells.

      The genes located along the X chromosome are called sex-linked genes; some of them are coded specifically for female anatomical traits, but other genes are responsible for more than three hundred genetic diseases, known as X-linked disorders. The fact that we have two X chromosomes in each of our cells may actually be one reason why women live longer than men – if one of our Xs contains a faulty gene, we have another X to step in. One example of this is red-green colour blindness, a common X-linked disorder. More men than women are colour-blind, because if the gene for colour is disturbed on their X chromosome, they don’t have a second one to use for backup. Having two Xs is like having an extra little black dress in the closet – or even better, having a few extra years of life in which to wear it.

      HYSTERIA