15 Apr 2013
HEIDI DOUGLASS | h.douglass@unsw.edu.au
Yes, it’s true. Women live longer than men. In fact not only does evidence suggest that we females have always outlived the blokes, it appears that as more time passes the gap is increasing. Currently Australian women can expect to live, on average, 5 years longer than our male counterparts, which is the same for most developed nations of the world. Why is this so?
No-one knows for sure, but there are a number of theories. According to CHeBA’s Co-Director Professor Perminder Sachdev, the first thing that people will say about this topic is that women have healthier habits and he thinks to some extent this is true. Women tend to smoke less, drink less, eat better and generally take care of their bodies. This may be a factor, but according to Professor Sachdev this isn’t a sufficient explanation because of a paradox, which is that even though women live longer than men, statistics show that they acquire more illnesses and visit doctors more than men.
So what about stress? Historically men have had the stress of going to work everyday to support the family and had to periodically go off and fight wars. Surely “life stress” has hindered men? Apparently not. Even though women’s lives have increased in stress with the elimination of male-female role stereotyping in the second half of the century, and the combined pressures of work and home on women, they still manage to live longer. Hence, stress isn’t a good explanation either. So what is?
I posed this question to my family, who, despite being in long and (so I thought) loving relationships, were all fairly cynical about the longevity of women. One family member told me: “They need to see their husbands die and the power of will is amazing”. No, that didn’t come from a female.
My surrogate grandmother, a mid-70s German that has lived in Australia for more than 50 years, made some sense. According to her, “there are biological differences related to hormones and childbearing [that make women live longer]. They are also better equipped to cope, and when husbands die earlier can look after themselves better than widowed men.”
My sister-in-law also made an interesting point, stating that “women are less susceptible to cell damage which is also why more girls are born than boys.”
My partner, in the health and fitness industry, may also be close to the mark with his statement that “women store body fat differently to men. The theory is that men immediately store body fat around their internal organs whereas a woman tends to store it in their hips and thighs (to protect the child bearing process). This disadvantage to men does not tend to affect women to the same extent until after menopause.”
My sister, (married for 15 years with four children), thinks it is “because we have more heart”. According to my mum women are just waiting a very long time for a break. And from my dad? Apparently "men can only take so much".
Hmm…on that note, let’s head back to the expert.
According to Professor Sachdev, we need to try to understand why we age. What are the processes at the biological level that make us age?
“We need to understand this because when you look at other species like rats or chimpanzees - even in those species females tend to have an advantage over males,” he says.
“A female rat in a laboratory will live longer than males. The female or worker honeybee lives a relatively long life whereas the male counterparts only live for a day or 2, with the express purpose of mating with the queen bee, and this is true of a number of other species as well.”
“People have looked at the reasons for this from various viewpoints. One popular theory for ageing is the wear and tear theory; that as cells divide, some defects accumulate in the cell, both in the DNA and the proteins that are formed. The body has a mechanism by which you can repair these defects and it is suggested that women do a better job of repairing these defects at a cellular level than men, and gradually with ageing the individuals that have a better repair mechanism will survive longer than those that do not. Hence, a major reason for women living longer than men is at the genetic level. And an obvious and major difference at the genetic level for women is that they have two X Chromosomes whereas men only have one X chromosome. The second major difference is in the hormones themselves. Women have oestrogen as a major hormone through their adult lives rather than testosterone - although of course after menopause that changes for women.”
It would appear that while testosterone gives men advantages in early life such as in increased muscle strength, it may actually be at a long-term cost for ageing. Oestrogen early in life is, on the other hand, a key factor in providing protective effects from the wear and tear mechanisms that are inevitable in the body.
According to Professor Sachdev, it has been shown that male animals have a tendency to live longer if they have been castrated. Scary thought for men! Historical evidence suggests that castrated men tend to live longer than uncastrated ones by about 14 years.
The fact is that a female child born today is likely to live into the early 90s, with far more women reaching this age than men. Western societies continue to see an increase in the lifespan and no one knows how far that will go. So far the longest living person (a woman) with a well-documented age died at 122.
Australia’s only study of centenarians is conducted by the Centre for Healthy Brain Ageing (CHeBA). With the centenarian population being the fastest growing demographic and predictions that by 2050 there will be over 2 million centenarians internationally (with up to 50,000 in Australia), it is worth finding out why this is so. And why the majority of centenarians are women.
As Professor Sachdev says, “It is not without reason that we call nature Mother Nature”.
