Why Do We Age

How and why do we age?

Ageing is 'The process of growing old' [1]. This is known information to almost everyone that as we age, we show more signs of ageing such as wrinkles or age-related diseases. However, the reasons for this is still not fully known and consolidated, which is why many theories about ageing exist and scientists are still currently researching this topic. This essay will cover well known theories and biological phenomena on the topic of ageing with critical evaluation in answering the title ‘How and why do we age?'

The first theory on why do us humans age is called 'The Somatic Mutation Theory of Ageing'. This theory (summarised) states that ageing is caused by mutations in our genes when they are copied incorrectly each
The biological phenomenon known as ‘Calorie restriction (CR)’ involves consuming less daily calories than average as the name implies. The link between ageing and calories has been made due to CR showing lower cholesterol, fasting glucose and blood pressure, which are considered to some as the ‘biomarkers of aging’ as they have a correlation to age related diseases [7]. So, CR lowers these biomarkers of ageing to help the organism to have a longer lifespan by reducing the risk of aged related diseases that are related. Extensive research has been done on this phenomenon and it is used as some as a remedy to live longer. In 1989, scientists in the University of Wisconsin primate centre used Rhesus monkeys, as they are genetically close to humans and have long lifespans, were used for CR research. What they found was that the Rhesus monkeys with the restricted diet were observed to look younger, they also have less heart disease and diabetes, with cognitive tests showing their minds were sharper compared to the monkeys who were free to eat what they wanted [8]. Having a high risk of heart disease and having a less sharp mind are signs of ageing as their body deteriorates over time, so this experiment is useful for giving us one of the reasons on why we age. However, while CR improved the health in these monkeys, a new study from the National
The shortening of Telomeres over time as cells divide more and more throughout our lifetime is one key reason on why we can succumb to ageing. When our cells become unable to divide and perform mitosis (cells divide into 2 identical cells), our current cells would wear out very quickly [13], when the cells wear out and do not divide as much, we will show more symptoms of ageing which could include wrinkles and saggy skin. The discovery of Telomeres come from three scientists. They observed that cells with mutations that made gradual shortening of the telomeres did not grow well and did not divide anymore after time, while one of them discovered that functional Telomeres prevented damage to the chromosome and delayed ageing, research was done to find that DNA sequence in the telomere will also attract proteins which will form a protective barrier around the ends of the DNA strands [14]. This research shows that on top of calories and mutations, these telomeres are also a big factor on why and how our cells age. We have telomeres to protect our cells becoming too short that they can no longer divide, they also form a protective shell at the end of DNA strands to protect them even further. This would mean that we age because of our cells losing genetic material each time they perform mitosis, and that without the Telomerase to