What is ageing?

It is said that age is just a number. And this is true. There is no answer to whether or when someone is old, because it is a purely subjective feeling. You are only as old as you feel. Average life expectancy has been increasing for years and has doubled for both men and women in industrialised countries over the last 120 years [Roser et al. 2013]. In Germany, life expectancy for girls born in 2021 is over 83 years and for boys over 78 years [German Federal Statistical Office (Destatis) 2020]. In addition, there are now more than 500,000 people worldwide who are 100 years old or older - a number that has more than tripled in the last 20 years [German Federal Statistical Office (Destatis) 2022]. The age record is held by Frenchwoman Jeanne Louise Calment, who died on 4 August 1997 at the age of 122 years and 164 days. In fact, many researchers consider an age of around 120 years to be a natural upper limit for humans [Dong et al. 2016]. This is based on the observation that while average life expectancy has increased over the last century, the maximum life expectancy has not changed and has remained almost constant at around 120 years.

But age and ageing are not the same thing. Age is just a number and is often subjective. Ageing, on the other hand, is an observable process that can be described and defined scientifically. In ageing research, ageing is defined as a progressive loss of physiological integrity leading to functional impairment and an increased likelihood of death [López-Otín et al. 2013].

The classic, verifiable ageing processes, such as the appearance of wrinkles and the decline in performance and endurance, begin to occur around the age of 20. The speed and continuity of the ageing process is influenced by several factors. Genetic factors determine about 10-15% of a person’s ageing process [Melzer et al. 2020]. Other factors include individual lifestyle and external environmental influences.