Have you gone to your GP and been told you’re as fit as a 21-year-old? No? How about a 50-year-old? Doctors and other health professionals often use descriptions like this, but what do they mean? 

The doctor is describing your physical conditioning or what’s regarded as your biological age, regardless of how many years ago you were born. 

Your chronological age will always be an easy-to-determine number, while your biological age depends on a number of changing variables.

Also known as physiological or functional age, biological age differs from chronological age because it takes into consideration factors other than just the day you were born. 

Scientists tell us biological ageing occurs as we gradually accumulate damage to cells and tissue in the body. 

Factors that influence this include:

• Chronological age.

• Genetics (for example, how quickly your body’s antioxidant defences kick in).

• Lifestyle.

• Nutrition.

• Diseases and other conditions. 

Using this information, medical professionals can figure out what age your body “acts” like it is, which may not be the same as your chronological age. 

For example, if you’re a 28-year-old male who doesn’t exercise, only eats high-fat foods, and has smoked five packs of cigarettes per day for the past 10 years, you would probably have a biological age of greater than 28 years.

Scientists have discovered a link between what we call ageing and the condition, or length, of a particular molecule present in most living organisms and viruses.

The molecule is called Ribonucleic Acid (RNA) and it is important in DNA coding and the manufacture of gene-related proteins. 

Scientists use the term “transcription” to describe the process of copying a segment of DNA into RNA. This process has been found to have an important influence on ageing. 

The researchers found that as humans, mice, rats, and killifish get older, the length of their RNA transcripts tends to shorten, creating an imbalance. Shorter transcripts are linked to common ageing conditions, such as inflammation, while longer transcripts tend to be associated with increased lifespan.

The researchers think the shortening of RNA transcripts, and therefore the number of shorter RNA molecules across cells and organisms, may be driving functional losses during ageing, rather than the traditional view that a few genes are responsible for what happens when living things grow older. 

When they analysed this phenomenon in animals such as mice and fish, nearly 80% showed a decrease in long transcripts. What’s more, similar results were found in human tissue, where it was strongest in brain cells.