It's been known for a while now that, generally speaking, women live longer than men, with some studies suggesting that males have a mortality rate that is up to 60% higher than females.
Traditionally, this difference in life expectancy was blamed on the greater risks taken by men in terms of accidents and illnesses linked to lifestyle, such as heart disease and cancers. However, in today's world when men and women live equally adventurous lives, such a simple explanation no longer rings true.
Now, scientists at Uppsala University in Sweden say that the so-called 'stronger sex' have their Y chromosome, or, specifically, the loss of it, to blame for their shorter lives. Only found in men, the Y chromosome is the sex chromosome which contains the DNA that makes males, well, male. It is present in nearly every cell in the body, representing almost 2% of the total DNA in cells.
However, in some men this chromosome starts to disappear from blood cells with age, and it is this process that researchers are saying may be the cause of shorter lifespans. Previous studies have associated this chromosome loss to a higher chance of developing a range of cancers, but it has now also been linked to Alzheimer's disease.
More than 3,200 men between the ages of 37 and 96 took part in the study, in which tests showed the Y chromosome to be missing from the white blood cells of roughly one in five participants, with this loss being more common in the older generations. Health records then showed Alzheimer's disease to be almost three times more common in men ffected by the phenomenon.
Furthermore, it was found that healthy men were almost seven times as likely to go on to develop the condition, which causes progressive mental deterioration, if they were missing Y chromosomes. This is because the white blood cells in question form part of the immune system, and it is thought that without their Y chromosome they struggle to work properly, leaving the body vulnerable.
Dr Simon Ridley, of charity Alzheimer's Research UK – the UK's leading dementia research charity – said: 'This interesting study points to a potential new avenue to explore for researchers investigating the development of Alzheimer's disease. Alzheimer's disease is the most common cause of dementia, and with no treatments currently able to alter its course, research to understand the disease is vital.
More reasons women might live longer:
This time we're talking about X chromosomes, of which women have two and men only have one (their equivalent of a second X chromosome is the very on-topic Y chromosome). This difference alters the way our cells age. By having two X chromosomes, women keep double copies of every gene. This means that, when one bunch of our cells (made up of X chromosomes) is ageing, we have spares. However, men don't have that back-up, increasing the risk of cell 'malfunction' and putting men at reater risk of disease.
Testosterone can be found at the centre of the longevity argument:research by the Endocrine Society in 2015 showed that high levels of testosterone leads the body to produce lower levels of 'good' cholesterol, which helps remove LDL (otherwise known as 'bad' cholesterol) from the body. This can therefor leave the male body more susceptible to cardiovascular disease.
Pre-menopausal women, on the other hand, have the sex hormone oestrogen to thank for their longer lives. Research at Queen Mary University, London, suggests that this hormone could help protect women from cardiovascular disease by keeping the immune system in check.
Compared to men, women are relatively iron deficient – especially when they are in their teens and early twenties – because of menstruation. Iron plays a very important role in reactions in our cells that produce free radicals which can in turn age our cells and weaken our immune systems. Therefore, having a large amount of iron in your system (which,as explained, is more likely to happen in men) can be potentially damaging your cells and increase the chances of developing cardiovascular problems later in life.