Holding hands on chilly walks through the countryside is one of the joys of this time of year.
But the real reason women love this gesture may have less to do with chivalry — and more to do with basic physiology.
As a Cambridge University study revealed last week, that’s because women’s hands tend to suffer the cold more than men’s.
It’s all down to muscle tissue, of which men generally have more than women do, and which is largely responsible for generating the body heat that keeps us warm.
This was discovered from tests in which scientists made 114 hardy volunteers plunge their hands into ice-cold water for three minutes and then monitored how quickly their hands warmed up.
A Cambridge University study revealed women have colder hands because they have less muscle mass and more fatty tissue which is less effective at stopping heat loss
The men, with their greater muscle mass, warmed up quicker than women, whose hands have more fatty tissue which is less effective at protecting against heat loss and helping with rewarming.
Stephanie Payne, the biological anthropologist who led the research, should be applauded for her bravery. In recent years, other scientists who have pointed out the physical differences between men and women have been roundly criticised.
For while all aspects of modern life — from the bedroom to the boardroom — are increasingly geared to ensure equality for all, Mother Nature keeps some distinctly un-PC tricks up her sleeve when it comes to basic physiology.
Believe it or not, science even reveals that some of the old battle-of-the-sexes cliches are entirely true — yes, men really are worse at listening during conversations . . . and at picking out paint colours.
Vive la difference? Biology certainly thinks so.
Men’s noses are bigger
Even if a woman and a man are physically the same size, the man’s nose is on average 10 per cent bigger.
Why? It appears that men’s bodies need more oxygen, so they grow bigger hooters in order to suck it all in. A study in 2013 by Nathan Holton, a professor of orthodontics at the University of Iowa, explains why.
Holton followed 20 men and 18 women from the age of three until their mid-20s to monitor the way in which their skulls grew. He found that boys’ skulls went through a growth spurt during puberty that put them a nose ahead.
This is the stage of life when boys begin to grow more lean muscle mass, while girls grow more body fat mass.
Lean muscle requires more energy — in the form of oxygen — for building and maintenance than body fat, explaining the need for boys to suddenly need more air.
Even if a woman and a man are physically the same size, the man’s nose is on average 10 per cent bigger because men’s bodies need more oxygen
…but can’t smell as well as women’s
Women’s noses may be smaller, but their brains can read much more from the air they do breathe in.
According to Brazilian researchers, women have more than 40 per cent more cells in the olfactory bulb, the area of the brain that controls our sense of smell.
In 2014, a team from the Federal University of Rio de Janeiro studied the brains of deceased adults and found that while men had some 9.2 million cells in their olfactory bulbs, the women had around 16.2 million.
The scientists suggest that this trait evolved to enable women to choose mates for reproductive purposes — by detecting subtle changes in men’s testosterone levels that indicate how fit, strong and healthy they are.
Seeing things differently
Ever wondered why women seem to get a lot more from browsing interior-decorating catalogues than men do? Well, it turns out that women are generally significantly better at discriminating between subtle differences in colour hues, according to 2012 research led by Israel Abramov, a professor of vision at the City University of New York.
His tests on men and women with normal colour vision and 20/20 sight found that men were especially poor at discriminating between colours at the shorter-wavelength end of our visual spectrum — that is, between different shades of violets and blues.
Men are also far more likely to have some form of colour blindness. The disorder usually has a genetic component and is rarely found in women.
But Abramov’s research doesn’t stop there. He’s also found that men are much better at spotting subtle movement than women.
This is linked to greater numbers of specialised neurons in the visual parts of men’s brains, and is thought to be an evolutionary development that gives them an advantage when hunting.
However, it also makes men less focused in social situations. When talking to someone, they are more likely to be distracted by movement behind that person.
Men are also far more likely to have some form of colour blindness. The disorder usually has a genetic component and is rarely found in women
Red for a boy, green for a girl
It’s not only ducks and dragonflies that have very different colourings according to their sex.
Human skins have different sexual ‘plumage’ too, according to researchers at Brown University in Rhode Island, U.S.
They analysed more than 300 faces to find a subtle yet fundamental gender difference in human faces: men are tinged red while women are tinged green.
What’s more, the research also demonstrated that we are sub-consciously able to pick up on this colour cue.
In tests, volunteers were able correctly to guess the gender of people in photos where their features had been blurred out, simply by focusing on the colour of their skin.
This instinctive colour perception may also help women to choose male partners, as it could give clues about men’s ability to forage for food.
Studies conducted by David Perrett, the head of St Andrews University’s Perception Lab, reveal that women are attracted to a subtle yellow tinge in men’s skin.
He suggests that this is because it indicates a diet high in carotenoids — healthy, pigmented substances found in fresh fruit and vegetables.
A question of backbone
Humans are the only species where the sexes have differently shaped spines. This biological curiosity has long puzzled scientists. It also puts millions of women at risk of the bone-thinning disease osteoporosis.
Now biologists say that women’s bodies have evolved this way because only a thinner spine enables them to carry a pregnancy while at the same time walking upright.
Specifically, the uniquely slim dimensions of a woman’s backbone allow her to shift weight around during pregnancy.
If women could not do this, the weight of the foetus would put immense pressure on the hips, rendering the mother immobile and putting her at risk of serious injury.
The gender differences in spinal shape are evident from birth, as shown by a study at the Children’s Hospital Los Angeles, in which 70 newborns had their bodies scanned in an MRI machine.The 2015 research found that baby girls’ spines are more than 10 per cent thinner than boys’.
Humans are the only species where the sexes have differently shaped spines. Now biologists say that women’s bodies have evolved this way because only a thinner spine enables them to carry a pregnancy while at the same time walking upright
No ear for conversation
Numerous studies have shown that women’s hearing works better than men’s — and the difference becomes greater with age.
Scientists disagree on why this might be (some even say it’s because young men are more likely to take silly risks such as listening to loud rock music).
However, another theory suggests that men tend to listen with only one side of their brains, while women use both.
This is according to a study by Indiana University which scanned the brains of 40 men and women and analysed activity in the temporal lobes — the area of the brain linked to listening and speech.
Most of the men only showed activity in the left temporal lobe, while most of the women showed activity on both sides of the brain.
This is especially revealing because the right temporal lobe is traditionally associated with performing music and understanding spatial relationships, meaning the scan results indicate that women’s brains may be more engaged emotionally while listening.
But this use of the brain can backfire, according to Swedish physiologists. Their tests showed that women who are feeling over-stressed tend to become hypersensitive to sounds around them (which only makes them more stressed).
‘In some cases, even a sound level corresponding to a normal conversation can be perceived as painful,’ says the 2013 study by Sweden’s Karolinska Institutet.
Men in the same situation, meanwhile, might simply shut off.