We have long been told that ageing, like the passing of time, is an inevitable, irreversible process. From a biological point of view, that belief is now changing. So what exactly is ageing?

The most widely accepted idea is that it is a part of the life cycle. But the ageing process doesn’t start at the same time for everyone, and not even all the organs in the same person age at the same rate. We talk about ageing as a wide-ranging phenomenon — it is a physical process, but also a psychological one, and a social one. 

The difference between chronological and biological age

Our chronological age is the age that appears in our passports — the number of years we have lived. It’s an objective measure. Our biological age, on the other hand, is the age we appear to have both physically and at a cellular level. For instance, there are ninety-year-olds who look twenty years younger. These people generally are fitter than most people of their age, and in fact there are ways of quantifying this (for example, by measuring the testosterone levels they generate).

When do we begin to age?

Around the age of 30 our bone mass stops increasing. It’s also said that after a certain age the brain no longer has the plasticity to learn new things. And the question of hormones is essential, such as menopause in women and declining testosterone in men. Some scientists believe that we start to age from the moment we are born. However, some others see it as the process in which most of our functions begin to diminish rather than grow, such as having fewer neurons, fewer nephrons, less muscle strength, and so on. This is all part of normal ageing.

Some scientists believe that we start to age from the moment we are born.

Ageing in cells

All cells experience changes with ageing. For instance, they become larger and are less able to divide and multiply. Many cells then lose their ability to function, or they begin to function abnormally. Waste products build up in tissue, and connective tissue changes, becoming more stiff. This makes the organs, blood vessels, and airways more rigid. Many tissues thus lose mass in a process known as atrophy.

Why do we age?

We don’t know for sure these changes happen as we get older. Some theories claim that ageing is caused by injuries from ultraviolet light over time, and wear and tear on the body. Most scientists however view ageing as a predetermined process controlled by genes, and have specifically identified the various hallmarks of ageing at a cellular level that include genomic instability, cellular senescence, stem cell exhaustion, and altered intercellular communication.

There isn’t one single reason responsible for all the changes of ageing, which is a complex process. Most gerontologists (people who study ageing) feel that ageing is due to the interaction of lifelong influences that include heredity, environment, culture, diet, exercise and leisure, past illnesses, amongst others.

Ageing is due to the interaction of lifelong influences that include heredity, environment, culture, diet, exercise and leisure, past illnesses, amongst others.

Ageing is a fact of life

As we age, from a strictly biological point of view, our organs start to lose their ability to function. As far as the symptoms of ageing are concerned, typical ones include hair turning white, men going bald, degenerating eyesight and hearing, and so on. Then there are factors that may increase the risk of disease. For instance, the pancreas ages and stops secreting insulin and we may develop diabetes; we may put on weight; our blood pressure may rise leading to a stroke or a heart attack. Unhealthy living habits such as smoking and drinking compound the risk.

Unhealthy living habits such as smoking and drinking compound the risk.

Inevitably, the ageing process is associated with illness. Rates of cancer, heart failure and dementia rise in older people as a direct result of ageing. And as age increases, morbidity rates also increase. While ageing in itself is not a cause of diseases, it however favours the emergence of it.

FY