Chapter 10
Why Do We Age? to Friendship
Technically, there is really no reason why the human body should age as long as it can repair and renew itself. Were this the case, individuals in the species would just keep on living until an accident or other external event killed them. Yet, as humans age, we experience changes to almost all physiological functions – hormones, the immune system, muscle function, heart function, lung function, blood systems and brain function. Therefore, something other than time must cause ageing. The programmed theory of ageing asserts that ageing is an intentional process, that is we are pre-programmed to age and die. The above diagram illustrates the differences in the average lifespan of different animals. (By permission Silvin Knight 2020. Data from S.S. Flower, ‘The Duration of Life in Animals’ in Proceedings of the London Zoological Society.) The rate-of-living theory states that humans and other living organisms have a finite number of breaths, heart beats or other measures, and that they will die once they’ve used these up. This is an attractive theory for which there is some evidence. There is a clear link between heart rate and lifespan in most animals. Small animals have higher heart rates and shorter lifespans; larger animals have slower heart rates and longer lifespans. There is as yet no definite evidence that humans have a finite number of heart beats, although people with faster resting heart rates die earlier. The free-radical theory is a well-known and much promoted ageing theory, particularly by corporates with a vested interest in supplements. When cells create energy, they produce unstable oxygen molecules called free radicals. Free radicals are some of the ‘waste’ products we referred to earlier. The theory posits that excess of free radicals causes accelerated ageing. Antioxidants are substances found in plants that soak up free radicals like sponges. In laboratory experiments, higher numbers of antioxidants minimise the damage caused by free radicals. However, most human studies of antioxidant supplements have not as yet shown the same dramatic effects. It is not entirely clear why this is the case but I will examine supplements in more detail later. The protein cross-linking theory attributes ageing to excessive binding between proteins in cells that forms rigid structures like ladders within the cell and causes the structural changes and stiffening characteristic of age-related disorders, such as hardened arteries, cataracts, skin wrinkles and lung fibrosis. Finally, a popular theory about ageing is that it is mostly due to inflammation occurring because of malfunctioning in our immune systems as we get older. Our immune system fights infection and anything else that is ‘foreign’ to the body. The effectiveness of the immune system peaks at puberty and gradually declines thereafter. Impaired immune responses lead to cell inflammation and eventually cell death.
Chapter 2: Why Do We Age?
Thanks to the global roller coaster that is Covid-19, we have all become very aware of the critical role the immune system plays and how fragile it is, particularly in older ages. Older people are twice as likely to have a serious response to Covid-19 as ageing immune systems make it harder to fight off the infection. Less than 1 per cent of people in their twenties died from the Covid-19 virus, compared with 20 per cent of over 80-year-olds. Overall, 80 per cent of deaths were in people over 65. In Italy, a country with one of the world’s oldest populations, the average age of death from Covid-19 was 81. This put a 20-year gap between the average age of people who tested positive for the virus and the deceased. Therefore, the potential to delay or reverse the effects of ageing on the immune system would have significant benefits for current and future infections. Understanding the cell changes that underlie the decline in immune function has advanced in recent years and clinical trials to evaluate various methods by which to enhance immunity are now underway, leaping to prominence because of Covid-19. In summary, it is most likely that all of the theories detailed above contribute, in one way or another, to cell ageing and cell death. Ageing is unlikely to happen because of a single reason – it is multifactorial. However, the good news is that the various interventions that we will discuss, such as food, hormesis, exercise, sex, laughter, friendship and sleep, all have their effects at the cell level through one or more of the pathways involved in the theories of ageing. A significant chunk of health budgets in Western countries is drawn down by age-related issues. Some argue that delaying ageing merely yields a one-time benefit after which the same healthcare expenses would ensue. But the evidence is to the contrary. We know from animal experiments that delayed ageing produces a genuine compression of diseases and death rates. In other words, if cell ageing is slowed down, it reduces the period of time at the end of life during which the animal experiences age-related diseases. For example, calorie-restricted animals not only experience a reduction in their risk of death but also declines in the risk of a wide variety of age-related conditions, such as cataracts, kidney diseases, arthritis, dementia, and many others. If this could be achieved in people, the benefits to health and vitality would begin immediately and the costly period of frailty and disability at the end of life would occur over a shorter interval before death. Such compression of diseases and disability would create financial gains, not only because ageing populations have more years to contribute but also because there would be fewer years during which age-entitlement and healthcare programmes were used. The pace of population ageing around the world occurs at different rates. France had almost 150 years to adapt to a change from 10 per cent to 20 per cent in the proportion of people older than 60. However, Brazil, China and India have had only 20 years to make the same adaptation. This will put huge pressure on health and social care systems in these countries. Thus the world faces major challenges to ensure that health and social systems are ready to address ageing demographics.
Chapter 2: Why Do We Age?
The countries in Europe where citizens enjoy the highest rates of good health after age 65 are Sweden and Switzerland. Why? What is different about Sweden and Switzerland? Explanations include better diets, good healthcare, high rates of physical activity and egalitarian societies. In other words, factors that are well within our control as individuals and as a society. Understanding the ageing process will not only inform what we can do as individuals to ensure longer, healthier lives but also how society can better assist its citizens as they age, ensuring equity.
Slowing down the process of ageing by just seven years could cut in half diseases at every single age. This would have a massive impact on human lifespan and healthcare costs. The Wright brothers, who built and flew the world’s first successful aircraft, looked at birds and thought, ‘These birds are heavier than air and they can fly. If birds can fly, we can make aeroplanes.’ And they did. There is no law of nature that says ageing is immutable. So, let’s be optimistic about what we can do for ourselves, both now and in light of new discoveries that are close to hand.
Chapter 3: Friendship
OUR FRIENDS AND RELATIONSHIPS LITERALLY KEEP US ALIVE. Even Albert Einstein recognised the influence of friendship: ‘However rare true love may be, it is less so than true friendship.’ When I started to study the association between family ties, friendship and health in the TILDA study, I was staggered by how powerful the physical effects of friendship are and how much difference good friendships make – and not only to pleasure and quality of life, but to hard outcomes like heart disease and even determining when we die. Good friendships add years to our lives.
Chapter 3: Friendship
I came across a lovely story recently of an unlikely ‘pairing’ that emphasised why friendship is important not just to us humans but also to other mammals. The story is about a rescue long-tailed macaque and a stray black-and-white kitten. The kitten wandered onto a Wildlife Friends Foundation park in Phetchaburi, Thailand, and was quickly adopted by a resident, Jojo. The macaque monkey had been rescued by the Wildlife Friends some years before when they came upon him cruelly caged in a restaurant. He was kept in the cage alone and was being used as a photo prop to amuse customers. Needless to say, the isolation that Jojo would have experienced is particularly painful for social animals like the macaque that, like ourselves, are a gregarious species, enjoying life in communities and organised groups. However, six years later, Jojo is a whole new monkey; he’s become the leader of a group of other rescued macaques at the wildlife rescue centre and has adopted a new best friend, the stray kitten. The furry duo has put species differences aside and share food, pose for pictures and even check each other for lice. The story exemplifies how friendship can unlock unexpected bonds and pleasures across species.