Surprising facts about ageing
Our genome is at constant risk of damage
The DNA in each of our cells gets damaged 100,000 times every day. On average, that’s more than one damage incident every second! With our bodies being made up of more than 1013 cells, this add up to a mind-blowing 1018 damage incidents our DNA sustains each day. That is a 1 with 18 zeros!
DNA damage, which accumulates in our cells over time, is one of the main causes of ageing. While we are young, our cells are good at repairing damage. But as we age, this repair becomes less efficient and we end up with permanent damage to our genetic code.
Cells with irreparable genomes can become senescent or die. This in turn drives the ageing process. If genes with important functions in the cell become damaged, the resulting mutations can also lead to cancer and other age-related diseases.
We start to age even before we are born
Ageing accompanies us throughout our whole life. Visible signs of ageing, like grey hair, wrinkles and age-related diseases become obvious only in later years. But biologically, our bodies start ageing already before we are even born.
Researchers measure our biological age by looking at so-called ‘epigenetic clocks’ that are ticking in each of our cells. Such clocks detect epigenetic marks: tiny chemical changes in our DNA. These small chemical groups can latch onto the DNA in different places. In doing so, they switch genes on and off. As we age, the occurrence of epigenetic marks changes in a predictable pattern. Researchers can measure the changes to calculate your biological age – which may well differ from what’s written in your passport.
A recent study in mice suggests that the youngest possible age is not reached at the time of conception as you might expect. Instead, the embryo goes through a rejuvenation event in the first couple of days and genuinely starts to age about a week into its development.
Women outlive men in most parts of the world
In Germany, children born after 2020 can expect to live up to 83.2 years if they are girls and 78.3 years if they are boys. What causes this difference of almost 5 years? Several reasons might contribute: on average, women visit doctors earlier and more often, drink less alcohol, eat a healthier diet and use less tobacco.
There might also be a genetic reason for this difference. Not only in humans but also in many other mammalian species, females outlive males. The possible reason: Female cells contain two X chromosomes while male cells contain one X and one Y chromosome. Women therefore have an extra copy of each gene on their sex chromosome that could step in if the other copy gets damaged. Which genes precisely are involved, however, still remains unknown.
It’s never too late to achieve something big
Colonel Harland Sanders pursued many different careers throughout his life. But only in 1952, at the age of 65, he franchised his secret recipe for fried chicken: the fast food chicken restaurant chain Kentucky Fried Chicken was born. Back then, Colonel Sanders was living off a monthly check over $105 from the US Social Security. Kentucky Fried Chicken quickly expanded throughout the US and globally, and became one of the most successful franchises of its time. At age 73, Colonel Sanders sold the Kentucky Fried Chicken corporation for $2 million.
Noah Webster Jr. was 70 when he published the first edition of his American Dictionary of the English Language in 1828. Today updated versions of his dictionary are better known as Merriam-Webster Dictionary.
And even at the age of 78 and older you might still have what it takes to become the most powerful politician of your country. In the 2024 presidential election, the United States will choose between candidates aged 78 and 81, making the winner likely the oldest person to hold office in the US.