London - We know men and women are different. But while physical build and sexual characteristics make this obvious - men are, on average, 15 percent bigger - there are plenty of more subtle differences between the sexes, too.
Last week a study controversially suggested that differences in the ‘hard-wiring’ of the male and female brain explained why women were likely to be better at multi-tasking.
Men, in comparison, are better at concentrating on single complex tasks, it seems. But what other physical characteristics mark men and women as different? And what are the implications for their health?
WHO CAN SEE COLOURS BETTER?
Women have a greater capacity to appreciate subtle tones and shades because their eyes have more ‘colour vision’ genes than men, explains Andrew Lotery, professor of ophthalmology at the University of Southampton. These genes help them recognise different colours and appreciate shades, tone and definition.
The genes are located in women’s X chromosomes - the genetic code which decides our gender. Men have one X chromosome, women have two, which is why women have more colour vision genes.
Having fewer genes also means men have a higher chance of suffering from colour blindness - if a woman has any missing or damaged genes, she has a ‘back-up’ set on her second X chromosome; men don’t have this. About eight in 100 men and one in 100 women are affected by colour blindness.
...AND WHOSE BONES ARE STRONGER?
The male skeleton tends to be bigger; but although a woman’s pelvis tends to be smaller, the openings between the pelvic bones tend to be bigger to allow babies to pass through.
“The downside of this is that woman are more prone to prolapse - a bulging down of the pelvic organs,” says Anton Emmanuel, consultant gastroenterologist at University College Hospital in London.
This occurs when pelvic floor muscles weaken, allowing organs including the bladder, uterus, small bowel, and rectum to fall out of position, causing pain and incontinence.
The cortex or outer layer of bone is generally thicker in men than women, so men are less susceptible to fractures if they fall, says Paul Allen, consultant orthopaedic and knee surgeon at Chelsfield Park Hospital in Orpington, Kent.
This is aggravated for women because their bones become thinner after the menopause as they lose oestrogen’s protective effect.
MEN NEED BIGGER NOSES
Men’s noses tend to be up to 10 percent larger because they need more oxygen than women, according to researchers at the University of Iowa. Men generally have more lean muscle mass, which requires more oxygen for muscle tissue growth and maintenance.
Larger noses mean more oxygen can be breathed in and transported in the blood to supply the muscle.
The size differences in noses become apparent at around the age 11, when men begin to grow more lean muscle mass and women grow more fat mass.
LARGER LIVERS COPE WITH BOOZE
The female liver, though proportionally smaller than a man’s, works just as effectively, except in relation to the effects of alcohol.
Female livers contain lower levels of an enzyme called dehydrogenase, needed to break down alcohol in the body, explains David Lloyd, consultant liver surgeon at Leicester General Hospital.
Therefore a woman will break down less alcohol and absorb more into her bloodstream than a man even if he weighs the same as her and has drunk the same amount. So she’ll feel the effects of what she drinks more quickly.
WOMEN’S HEARTS CAUSE TROUBLE
The female heart is about two thirds the size of a man’s and beats slightly less frequently - on average around 72 beats per minute instead of 80. Women who suffer with an irregular heart rhythm, known as atrial fibrillation (AF), are at greater risk of stroke than men, says Dr Glyn Thomas, a consultant cardiologist at the Bristol Heart Institute.
Strokes are a complication of AF and seem to occur more in women than men - possibly because they are more prone to high blood pressure after the menopause (and they’ve lost the protective effects of oestrogen) and high blood pressure is another stroke risk factor.
Women’s arteries can be smaller than men’s, which can be a health risk as they age, adds Eddie Chaloner, a consultant vascular surgeon at Lewisham General Hospital, London.
“Arteries can fur up as part of the ageing process. But if that is accelerated, by risk factors such as smoking, there’s a greater chance they will get blocked in women because the width of the artery is smaller.”
There’s also a higher failure rate for women in heart operations such as coronary bypasses and putting in stents (tiny tubes used to open up blocked arteries) because operating on smaller vessels is more difficult.
...AND SO DOES A LONGER BOWEL
Though women tend to be a smaller build than men, their colons are the same size - so they are disproportionately longer for their bodies. This may be to help the body absorb more fluid during pregnancy. However, having a disproportionately longer colon can make a woman more prone to bloating.
This is because the colon’s sole function is to absorb water, so more is retained in their stomachs. Women also feel full more quickly than men, even when they eat the same amount of food. “Not only are female stomachs slightly smaller, but there is a greater nerve input and sensitivity from their gut to the brain, which means they get messages more quickly that they feel full,” explains gastroenterologist Dr Emmanuel.
WHOSE LUNGS WORK HARDER?
Women’s lung capacity is about 30 percent less than men’s, explains Dr Rohit Lal, a lung cancer specialist at Guy’s Hospital in London. Women’s lung muscles may have to work harder than men’s because their lungs are smaller and their airways narrower, making breathlessness more common after exercise.
Because women are a smaller build, their lung muscles have to work harder than men’s to move a given amount of air, adds John Dearing, a sports injury surgeon at Carrick Glen Hospital in Ayr. It could explain why women with emphysema and heart failure - where the heart can’t pump oxygen around the body as efficiently - have worse problems with breathing than men.
WHY GIRLS CAN DO THE SPLITS
Women have looser ligaments than men, possibly to help the pelvis expand more easily during childbirth. Ligaments are the tissues that connect bones to each other and should be tight to restrict joints to ‘normal’ ranges of motion.
Looser ligaments mean women have a greater range of movement, which may make it easier for them to do the splits, for example.
But this can be a disadvantage, as it means women are at greater risk of joint injuries, explains Professor Alan Silman, consultant rheumatologist and medical director of Arthritis Research UK.
Young women are more likely than men to have bad knees as the flexible cartilage tissue in knee joints tends to be more elastic. It tends to tighten up as women reach the age of 40, but why is unclear.
Women may also suffer with knee pain because their wider pelvis causes the thigh bone to come down to the knee at a wider angle, says sports injury surgeon Mr Dearing.
“This creates a tendency for the kneecaps to push outwards and so makes this area more vulnerable to injury, pain and arthritis.”
AND ARE ALWAYS IN THE LOO
Our bladders are in proportion to our bodies. However what sets men and women apart is the size of the urethra - a tube that drains urine from the bladder.
“In a woman this will be around 3cm long, whereas in a man it can be as long as 20cm,” explains Christopher Eden, a consultant urologist at the Royal Surrey County Hospital, Guildford. That’s why women are more prone to urinary infections as there is a shorter journey up the urethra for bacteria.
BEER BELLIES vs PODGY HIPS
Women tend to put on weight more easily - men have a higher proportion of lean muscle mass, which means they burn calories more efficiently. That’s why men who weigh the same as women can eat 300 calories a day more without putting on weight.
“The male resting metabolic rate is higher than a woman’s so a man needs more calories to maintain the same weight as a woman does,” says Dr David Ashton, medical director of the Healthier Weight centres.
Men tend to put on weight around their middles - known as belly or visceral fat - while women tend to accumulate it around thighs and hips. Belly fat has been linked to a higher risk of diabetes, heart disease and high cholesterol. “However fat around the hips and thighs has no such impact - it may even be protective against heart disease,” adds Dr Ashton. One advantage of women carrying more body fat than men is they are better insulated from the cold. “So if a man and woman fall into the North Sea, the woman has a better chance of survival,” adds Dr Ashton.
But it may also explain why women feel the cold more. When cold, our bodies conserve heat by reducing the blood flow to the skin. The temperature of the skin then drops as the blood has been moved below the layer of fat. Men won’t experience as big a change because they don’t have the same fat distribution.
HOW WOMEN’S VOICES CHANGE
Men have deeper voices because their vocal cords are longer and thicker, explains John Rubin, a consultant at the Royal National Throat, Nose and Ear Hospital in London. This difference evens out after the menopause when lack of oestrogen can cause swelling in the vocal cords, which makes the female voice sound much lower.
Both sexes have an Adam’s Apple, a lump of cartilage at the front of the thyroid gland to protect the vocal cords. But because men have more cartilage, it sticks out more, explains Dr Rubin.
THEY HAVE THINNER SKIN
Women are more vulnerable to wrinkles because they have thinner skin, says Dr Sajjad Rajpar, a consultant dermatologist, from the Edgbaston Hospital in Birmingham. “Because of their thinner skin, as they lose collagen with ageing, they are more likely to develop lines and wrinkles.” Collagen is a protein which gives skin its support and elasticity. Men also have a higher collagen density - the ratio of collagen to skin - which is why they may look younger for longer.
...BUT ARE LESS DISEASE-PRONE
Women may have a more active immune system. In an experiment involving healthy male and female mice, a study by Queen Mary University, London, found that the females were better prepared to fight infections and their bodies suffered less damage after an infection. It seemed to be because female mice had twice as many infection-fighting white blood cells, and these were also more effective at fighting bacteria.
However, it’s believed the female immune system can be too active, which is why women are more vulnerable to auto-immune diseases, such as rheumatoid arthritis, in which the immune system attacks the body’s own tissues.
According to Dr Matthew Buckland, consultant immunologist at Barts Health NHS Trust, one possibility is that oestrogen increases activity of the immune system while male hormones may dampen it down. Research also found the female immune system ages more slowly, which could help explain why women live longer than men. - Daily Mail