For millennia it has been the dividing line in the battle of the sexes. Women may be better at multi-tasking, less susceptible to 'man flu' and safer behind the wheel — but, physically, men are the stronger sex.

And no wonder: on average, males are 6in taller than females and have twice the upper-body strength, as well as denser bones, stronger tendons and greater muscle mass.

Wonder Woman may be taking cinemas by storm this summer, but it's always Superman, with his rippling abs and bulging biceps, who saves the damsel in distress.

From longevity and surviving illness to coping with trauma and managing pain, we investigate the surprising ways in which women really are the stronger sex

However, this could be about to change. For a growing body of scientific study is turning centuries-old gender research on its head — by suggesting that women are, in fact, stronger than men.

'We often think of males as being the tougher and more powerful sex,' explains Angela Saini, author of Inferior, a ground-breaking new book which charts the scientists' findings.

'But strength can be defined in different ways. When it comes to the most basic instinct of all — survival — women's bodies tend to be better equipped than men's.'

From longevity and surviving illness to coping with trauma and managing pain, we investigate the surprising ways in which women really are the stronger sex...

ADVANTAGE GIRLS... EVEN IN THE WOMB

Girls' edge over boys doesn't just start at birth — it's there in the womb. Scientists at the University of Adelaide say this may be because a mother's placenta behaves differently depending on the gender of her baby.

Boys are bigger and grow faster in the womb, which can place a strain on the placenta and lead to under-nourishment of the foetus and high blood pressure in the mother.

'With female foetuses, the placenta does more to maintain the pregnancy and increase immunity against infections,' adds Angela Saini. 'Why this is, nobody understands.'

One possible explanation, she says, is that biologically, male foetuses are slightly more common than female ones. 'The difference . . . might simply be nature's way of correcting the balance.'

Scientists at the University of Adelaide say this may be because a mother's placenta behaves differently depending on the gender of her baby

PREMATURE BIRTHS ARE A BIGGER RISK TO BOYS

Boys are 14 per cent more likely than girls to be born prematurely, partly as a result of this under-nourishment in the womb.

Professor Joy Lawn, a neonatologist and epidemiologist at the London School of Hygiene & Tropical Medicine, who conducted a 2013 study into premature births worldwide, says it's the 'biggest risk for baby boys'.

'Even in the womb, girls mature more rapidly than boys, which provides an advantage because the lungs and organs are more developed,' she adds. 'In the UK, an extra 6,000 boys or so are born pre-term each year.'

This means male babies are less developed, which can put their early lives at risk. If a baby boy and girl get exactly the same neonatal medical care, boys are statistically 10 per cent more likely to die.

SOB STORIES MAKE MEN CRY THE MOST

They may act tough, but men are more emotionally fragile.

A UK study that exposed six-year-old boys and girls to a recording of a crying baby found that boys experienced a higher release of stress hormones.

The same researchers also said that boys cry more when upset and take longer to calm down.

The results were confirmed by 2015 neurology research, in which a group of men watched a series of emotional videos — categorised into 'blissful', 'exciting', 'heart-warming' and 'funny' — while their responses were measured via electrodes in their brains.

Men had stronger emotional reactions than women to all four, and responded twice as much to the heartwarming content.

A UK study that exposed six-year-old boys and girls to a recording of a crying baby found that boys experienced a higher release of stress hormones

A HIGHER IQ THAN ALBERT EINSTEIN

The debate over the differences between male and female brains has raged for many years, but new research shows they're far more alike than we imagined — and women have the upper hand.

The hippocampus, the part of the brain associated with emotions and memory, is similar-sized in both sexes. But women have more connections going from left to right across the two halves of the brain, which gives them an advantage in pulling together information from different sources and drawing logical conclusions.

Women consistently outperform men in IQ tests and the highest IQ score ever was recorded by a woman: American author Marilyn vos Savant, who, in the Eighties, got a sky-high score of 228 (far outranking Albert Einstein, between 160 and 190).

This mental strength gives them advantages in education and the workplace, too. Women now account for around 60 per cent of the world's degree-holders, while according to a recent report by McKinsey Research, companies led by women perform better and have more clout than those run by men.

SUPER-POWERED IMMUNE SYSTEM

It's no surprise that adult women's bodies have high levels of oestrogen and progesterone, the female sex hormones. But did you realise that these help to make their immune system stronger and more flexible?

A 2009 Canadian study found these hormones act against a certain enzyme which — in men — hinders the body's defences against bacteria and viruses.

There are two reasons women need a stronger immune system. The first is evolutionary. Dr Leslie Knapp, of the University of Cambridge, says women are better equipped to fight off illness because they're built to carry on the species: 'It only takes one male to reproduce with lots of females, but females are much more important in terms of producing offspring.'

A 2009 Canadian study found these hormones act against a certain enzyme which — in men — hinders the body's defences against bacteria and viruses

FORCE OF NATURE It's hard to argue that women are physically stronger than men (although some certainly are — recent statistics have shown a spike in the number of female bodybuilders in the UK). On average, men have bigger builds, with more muscle compared to fat, and a more even fat distribution throughout their bodies. However, a fit woman generates the same force per unit of muscle as a similarly fit man; she just has a lower total muscle mass (as opposed to less muscle strength) so can’t lift the heaviest weights. Women’s legs may even be stronger than men’s, muscle for muscle. Comparing leg strength to lean body weight (that is, a person’s weight not including the weight of the fat on their body), women’s legs are actually 5.8 per cent stronger than men’s. Advertisement

The second explanation is biological, based on the fact that women can bear children. In very basic terms, a pregnancy is the same as foreign tissue growing inside a woman's body. Normally, a person's immune system would reject any such foreign matter.

But unlike men, women's immune systems have two gears: one that can attack the bug making her sick, and another that can nurture the new tissue of a growing foetus. This flexibility makes pregnancy possible — and makes women stronger and better at battling disease.

But women's powerful immune systems can sometimes attack themselves, making them more prone to autoimmune diseases such as rheumatoid arthritis, lupus and multiple sclerosis.

WHY WOMEN DON'T GET 'MAN FLU'

If A nasty bug does penetrate that iron-clad immune system, women still have the advantage: they fight off sickness faster.

Studies have shown that females have more white blood cells

Studies have shown that females have more white blood cells, the parts of the blood which produce antibodies — natural proteins which neutralise bacteria and viruses.

Disease therefore progresses faster in men — and tends to take hold earlier in their lives. In 12 of the 15 most common causes of death, including cancer and heart disease, men die at a much higher rate than women.

Dr Steve Austad, a leading authority on the science of ageing from the University of Alabama, says women are far more robust.

'Pretty much at every age, women seem to survive better than men,' he explains. 'Once I started investigating, I found that women had resistance to almost all major causes of death.'

The fairer sex are even better at battling coughs and colds, suggesting that 'man flu' — that infamous ailment which floors even the healthiest men — may actually exist.

AND THEY'RE NOT SCARED OF DOCTORS

Of course, social factors are at play, too. Not only are women biologically stronger when they're sick, but they're far more sensible about it.

British researchers have found that women are better than men at reporting poor health, and more likely to seek medical help when they first experience symptoms.

According to the National Pharmacy Association, men visit their GP four times a year compared to six times for women, visit a pharmacy four times a year compared to 18 — and are twice as likely to take medication without reading the label.

The study also found that nearly nine in ten men don't like to trouble medical professionals unless they have a 'serious problem'. That lack of oversight may help to explain why 36 per cent are obese (compared to 28 per cent of women) and why men are twice as likely to have an alcohol disorder.

British researchers have found that women are better than men at reporting poor health, and more likely to seek medical help when they first experience symptoms

ARE HORMONES THE KEY TO A LONG LIFE?

Of THE 43 'supercentenarians' in the world — people over 110 years old — 42 are women.

In Britain, there are 150 people over the age of 107, only eight of whom are men.

Bessie Camm, a former nurse from Rotherham, Yorkshire, is the UK's oldest person at 112, and puts her longevity down to 'hard work, knowing lovely people and good food'.

Scientists still haven't pinned down the reason for this longer lifespan, with potential explanations including lower blood pressure (men tend to have riskier jobs and lifestyles) and the idea that a woman's heart rate increases during the second half of her menstrual cycle, offering the same benefits as moderate exercise.

Expert on ageing Dr Austad says it may once again be down to hormones. 'Some research suggests that hormones given for a few weeks early in life can have huge effects,' he explains.

Studies of men who have suffered castration, thus cutting off their supply of male hormones, suggest that the earlier this happens, the longer they are likely to live.

DNA THAT'S GOT THE XX FACTOR

Men may not be from Mars, but they do have very different DNA to women.

The bundles of DNA within each of our cells are known as chromosomes. These come in pairs, and in the 23rd pair — which determines gender — women have two X chromosomes, while men have an X and a Y.

Scientists say this difference affects our health. Women, with two versions of the X chromosome, have a back-up copy in case one is faulty or goes wrong.

Men, on the other hand, have no spare if their cells malfunction or if there's a genetic mutation on the X chromosome which causes illness or disability.

Women, with two versions of the X chromosome, have a back-up copy in case one is faulty or goes wrong

This affects everything from life-altering conditions to something as basic as temperature.

The double-strength XX chromosomes make women more resilient to hot and cold (women also deal well with cold because they have deeper layers of fat under their skin, which keep them — and their babies — warm).

Meanwhile, men are more vulnerable to certain genetic disorders that affect the X chromosome.

These include red-green colour blindness, haemophilia (which stops the blood from clotting) and muscular dystrophy (degenerative muscle wastage).

'Mental retardation, which affects . . . significantly more men than women, also has a strong link to the X chromosome,' explains Angela Saini.

THE PERILS OF PLAYING THE FIELD

Even in the animal kingdom, males are renowned for being promiscuous — and this gives the females a crucial advantage.

'Men produce lots of sperm and don't necessarily need to invest in their children, while women have only a couple of eggs to fertilise at a time, followed by nine months of pregnancy and many years of child-raising,' explains Angela Saini.

Therefore, women are often choosier about picking a mate, which makes their sex lives safer than men's, as they're less likely to sleep with a stranger or risk contracting a sexually transmitted disease.

Women are often choosier about picking a mate, which makes their sex lives safer than men's, as they're less likely to sleep with a stranger or risk contracting a sexually transmitted disease

YES, LADIES, YOU'RE BORN SURVIVORS!

In PURE biological terms, women are better at dealing with traumatic events such as car accidents, heart attacks and other types of shock.

According to a 2009 study at the University of Florida, females have a higher tolerance for pain (which helps when it comes to childbirth). There's also the size factor: men tend to be bigger, so they have more cells in their bodies, which means a bigger total number of cells are likely to be damaged in a traumatic event and slows their rate of recovery.

Dr Austad says women are, quite simply, 'better survivors'. 'Part of the reason there are more women than men around in ill health is to do with the fact that women have survived events that would kill men,' he adds.