31 Aug 2013

Reason Why Women Live Longer Than Men, Extra X-Chromosome

It is a phenomenon seen in every population and every country - women live longer than men. It is generally believed that the reason for this is because men do more dangerous things, that is, they take a lot of risks, they don’t go to see doctors until when their condition got out of control and therefore die earlier. But a new study has proved this wrong.

Have you ever wondered why women live longer than men? Well, the reason is not the fact that the latter are exposed to more stressful way of lives and unhealthy habits such as smoking and drinking.The reason is simple: it is in their genes, suggests a new study.

The secret to women’s stronger immunity lies in a key biological difference between the sexes - stronger immune system to the genetic benefits of having two X chromosomes, while men have only one and a much smaller Y-chromosome.

Women are known to have lower incidence of cancer - men have a two- to five- times greater risk of developing the disease. Women are also better able to survive trauma, and according to some reports don’t get as seriously ill from bacterial and viral infections.

The study also says that the woman’s system is genetically programmed to better resist infections and also has a back-up system for fighting disease.

This means women have greater access to molecules called microRNAs, which are encoded on the X-chromosome. These tiny strains of ribonucleic acid are regarded as major regulators of the immune system.

Dr Claude Libert from Ghent University in Belgium led the research which drew up a detailed map of all the microRNAs in X-chromosomes found to have a role in immune functions and cancer.

He said: ‘Statistics show that in humans, as with other mammals, females live longer than males and are more able to fight off shock episodes from sepsis, infection or trauma.

‘We believe this is due to the X-chromosome, which in humans contains ten per cent of all microRNAs detected so far in the genetic code.’ Several of these are thought to have ‘important functions in immunity and cancer’, he said.

An Abuja based  medical practitioner,Dr. Agadu Charles disagrees with the notion that women are genetically programmed to resist infections.

He explains: “ It should be the other way round. Take for instance, in the transmission of most Sexually Transmitted Diseases(STDs), it is the female specie that is at a higher risk of infection because the anatomy of the female’s reproductive organs are designed to receive what comes out of the male and most times it is at the receiving end. The virus/bacteria are able to move rapidly to a safer region within the vagina/cervix or ascend upward to the fallopian tubes as in the case of Pelvic Inflammatory Disease (PID) which is an ascending infection”.

Men on the other hand cannot easily contract these infection except on repeated exposure because they could easily induce diuresis by drinking a lot of water before the act and pass out any virus or bacteria contacted, he added.

Women may have extra X chromosome while the men have Y chromosome but these are basically for reproductive purposes. That is why it is the man that has the key to a male child in a family which is the extra Y chromosome. This may not really have anything to do with immunity, he posited.

Women live longer because they don’t go through the kind of stress men go through. The man is stressed day and night in order to cater for his family so as not to be labelled a failure. All these expose the man to health hazards such as high BP, low immunity, accidents, heart attacks which may be why they may have a shorter life span than the women, he stated.

Dr Eleanor Fish, professor of women’s health and immuno-biology at the University of Toronto, said of the findings in the BioEssays journal: ‘The advantages of having two X-chromosomes as opposed to an X- and a Y-chromosome are huge.

‘MicroRNAs are very important for regulating proteins that would influence cell growth and cancer, and the immune response.

‘They can suppress proteins that promote cancer and boost proteins that do the opposite.’

If women develop a mutation on a gene linked to the immune system on the X-chromosome, they have a backup copy. But men do not.

From a biological point of view, she added, the difference has probably evolved because women are more likely to ensure the survival of a species.

They need to be able to resist infection when pregnant and when nurturing the child.

‘You don’t need many men to keep the human race going but you need females,’ she said.

Also, researchers in the Netherlands think they may have an answer to why women live longer than men. According to them, menstruation increases women’s life span. When women menstruate, they release a hormone called estradiol. This hormone basically gives the heart a workout. During the second half of a menstrual cycle (and during pregnancy), the female cardiac output increases around 20%. This increase is equivalent to what happens when someone exercises. So basically the female heart gets a sustained workout for a few days every month. The result? Less cardiac problems than men.

More  Reasons Men Die Sooner Than Women

Criminal Activity

Men who live a life of crime may increase their risk of dying from an altercation, homicide or other risky, unlawful venture. Throughout history and across all societies, men commit more crimes in nearly every crime category.

Bigger body size

Bigger isn’t always better as it pertains to longevity. “On average, people over 6 feet tall don’t live as long as people shorter than 6 feet tall.

Heart disease

Higher levels of estrogen in women protect them from heart disease for 10 to 15 years longer than men.


Men have an XY chromosome, while women have an XX. If a defect manifests on the X chromosome, it is possible that the genetic material on the extra X chromosome in women provides some type of backup for the expression of the good genes.

Smoking, eating and drinking to excess and internalizing stress can contribute to increased blood pressure and heart disease risk, which cause men to die sooner.

Greater immune system challenges

One reason men don’t live as long as women is directly tied to the immune system. Women live longer than men in general because they’re born with longer telomeres (components at the end of chromosomes that act as an index of cell age), which are basically your biological clock.

High-risk occupations

A man’s occupation may also play a role in his reduced life span. The top three most dangerous occupations, aircraft pilot, fisherman or logger topped the list — positions all predominantly held by men.

No comments:

Post a Comment


Related Posts Plugin for WordPress, Blogger...