We are all subject to its whims and impulses, from the tummy butterflies of that first flush to the physical pain of its withdrawal. We all know its unique power to shape the parent-child relationship and, if we’re lucky, we’ve felt its gentle warmth as we’ve looked at the face of a friend. Even a fluffy one.
But what do we really know about love? The poets have long given us their thoughts, but now science is getting in on the act too. Thanks to ever-improving technology, modern scientists are able to look inside the human — and non-human — brain to find answers to some of our oldest questions on all things amorous. They can pinpoint the neurochemicals that form the very foundations of love, calculate the equations that add up to sexual attraction, and even suggest a scientific basis for why your husband forgets your wedding anniversary.
Now Oxford University anthropologist Anna Machin has scoured the studies and spoken to the leading experts for a new book, called Why We Love.
So read on for all you ever wanted to know about that sweetest and strongest of all human emotions . . .
Anna Machin reveals her findings on love after scouring studies and speaking to the leading experts for a new book, called Why We Love (file image)
DRESS SIZE DOESN’T MATTER BUT THE HIPS DO
The human mating game is a competitive market akin to the stock market, but rather than our worth being expressed in pounds, it’s expressed in mate value.
Evolution wants women to be able to get pregnant and be healthy enough to live to raise the child. For men, it’s all about their ability to protect, provide and commit to their family — remember when this system evolved, women were either pregnant or breastfeeding constantly, so were very vulnerable.
To be able to make this calculation, your brain uses your senses to take in key indicators. A woman’s waist-to-hip ratio, for example, is one of the most robust indicators of health and fertility, and cross-cultural studies of female body shape have repeatedly shown that the most attractive waist-to-hip ratio is 0.7 — the classic hourglass. This might surprise you because of our overwhelming focus on thinness, in the West at least.
But remember it is the ratio of waist to hips that’s key, so you can be a size 8 or 18 and the 0.7 is still what’s important.
Indeed, we’ve observed its importance not just in the lab, but in real life. In a 2015 eye-tracking experiment, scientists in Texas showed that men, and interestingly women, focused first and spent the longest time looking at an unknown woman’s midriff before moving on to her face, suggesting that when deciding who to approach as a potential mate — or checking out the competition — the waist-to-hip ratio is one of the first pieces of information processed by our brain.
Men are meanwhile assessed on their shoulder-to-waist ratio — a 1.4 is the goal, although that’s rarely displayed nowadays by anyone other than an Olympic athlete or gym junkie.
In a fling rather than committed relationship, women are more apt to go for good looks in the form of a symmetrical face. For both sexes, symmetry is a sign of good genes, and if he’s not in it for the long haul, his genes are the only thing she’ll be getting from him.
Overall, however, the sexiest organ in the human body is arguably the brain. The use of creative language, artistic expression and humour are indicators of our cognitive flexibility, which we’d all like our offspring to inherit because it’s linked to intelligence. It’s for this reason, in part, that famous rock stars or even politicians — think Mick Jagger with eight children or, ahem, Boris Johnson with seven — seem to have above-average reproductive success. Women seem to find them irresistible despite the fact they don’t stick with one mate.
Cross-cultural studies of female body shape have repeatedly shown that the most attractive waist-to-hip ratio is 0.7 — the classic hourglass (file image)
CAN A POTION MAKE ME SEXIER?
For thousands of years, humans have sought to control love through potions and elixirs.
In Shakespeare’s A Midsummer Night’s Dream, for example, Oberon, king of the fairies, administers a love potion to his sleeping wife Queen Titania which has the effect of making her fall in love with the first being she sees on waking; in this case, an ass-headed man called Bottom.
But for the first time, as our knowledge of the neuroscience and physiology of love continues to grow, the possibility of an elixir that actually works is tantalisingly close. Fancy adding a squirt of oxytocin, the so-called love hormone, to your pre-going-out ritual of a couple of glasses of prosecco and a dance around your bedroom?
Oxytocin is available for next-day delivery from Amazon and eBay, in the form of various products which claim to reduce social anxiety, make orgasms more powerful and potentially be a helpful aid to increase your confidence during the search for a mate.
Does it really work? Well, we know that oxytocin lowers our inhibitions to forming new relationships and increases empathy. One study found that couples who had been together for three months had significantly higher levels of circulating oxytocin than singletons.
And it’s certainly the case that a squirt or two of oxytocin up the nose works well for some, although many of the reviews on Amazon attest to its power not to make him fall for you, but to encourage milk let down in breastfeeding mothers (oxytocin plays a crucial role in childbirth).
We also know it can have negative effects too. As one reviewer puts it: ‘[Oxytocin] just made me tired and emotionally crotchety like an oestrogen-dominant bag of self-pity.’ Oh dear. In fact it’s becoming clearer with every scientific study that the impact oxytocin has on you is highly individual. For those of us who study the neuroscience of love, this is unsurprising.
The brain chemistry that prompts us to form and maintain our relationships is incredibly complex and finely balanced, and we still don’t have a clear picture of which chemicals complement each other and which are antagonistic.
Perhaps stick to a squirt of Chanel No.5 instead (and not up the nose).
ARE WOMEN MORE ROMANTIC THAN MEN?
Take 32 people who are romantically in love, 16 men and 16 women, and place them individually in an fMRI scanner, which maps brain activity. Show them a series of pictures of incidences of love, from the classic couple holding hands in front of a sunset to carrying out the weekly supermarket shop. What would you see?
One psychologist and her team did this to try to understand whether differences we think we know about men’s and women’s approaches to love had any biological truth.
Overall, what they found was that, regardless of sex, the more romantic the scenario — sunsets rather than supermarkets — the more the emotional centres of the brain lit up, in both men and women.
But if we look beyond these similarities, differences do emerge.
Some studies have shown that by the time children are eight, boys and girls are beginning to conceptualise romantic love in different ways (file image)
Areas of the brain engaged in thinking rather than feeling are more active in men, suggesting that evaluating and considering romantic scenarios is a more effortful process than it is for women, where it is more instinctive.
Could this be his excuse for forgetting your wedding anniversary? My husband finds the conclusion to this study ‘profoundly patronising’, because it implies that men are less emotionally literate, or evolved, than women.
But perhaps it’s nothing to do with evolution. We know that the human brain is highly plastic. It can change, particularly in our earliest years, and our environment has a key role in moulding it.
So it may be that our culture — which tells boys that they are the rational sex while women are at the mercy of their emotions — has caused our brains to appear the way they do on the scanner screen. Other studies have shown that by the time children are eight, boys and girls are beginning to conceptualise romantic love in different ways.
And we also know the pink aisle in the toy shop is full of hearts and flowers while the boys’ aisle, well, isn’t.
MAKE HIM FALL FOR YOU — GO TO THE GYM!
By harnessing the power of that heady love chemistry in other ways, you might just increase your chances.
Oxytocin is one of the ingredients of the romance cocktail, but it’s also joined by dopamine, serotonin and beta-endorphin — all happy chemicals which influence the fine detail of brain activity. Beta-endorphin is perhaps the most important of all. This is the body’s natural opiate, like heroin or morphine, so once someone has experienced an interaction that causes a release of it, they will keep coming back for more.
Anna Machin revealed a date full of endorphin-inducing activities can lead to success, such as exercise, dancing or a comedy club (file image)
We are addicted to the wonderful feelings of warmth, closeness, euphoria and happiness that it engenders. When we interact with someone we love, we get a hit of opiate, but if we go away our levels drop, our cravings begin and we are motivated to return to the source, meaning that we are constantly drawn back to the relationship.
The downside of this is that if we get dumped we go into a massive opiate withdrawal, which is why losing love is such a physically and psychologically painful experience.
What does this mean for dating success? Arrange a date full of endorphin-inducing activity. Exercise will do it, as will laughing, so a work-out session, ballroom dancing or a comedy club are good bets to increase the chances that the object of your desire will fall for you.
By contrast, since breaking up leads to a severe case of cold turkey, going for a run, or having a massage, which stimulates the production of oxytocin as well as beta-endorphin, will top up your supplies. A good chocolate-eating session will meanwhile restore your dopamine levels.
DO MUM AND DAD LOVE US DIFFERENTLY?
Yes, thanks to an evolutionary quirk that means homo sapiens dad was roped into childcare much later than mum.
The quirk relates to the massive size of the human brain – it’s six times bigger than it should be for a mammal of our size, which means that if a baby went full term, her head would not fit through the birth canal, mum and baby would die and the species line would come to an abrupt end. We’ve evolved therefore to birth our babies very early, resulting in a baby whose brain is not yet fully developed – and hence is incapable of doing anything alone for a significant period of time post-birth.
Anna said mothering is as old as time, present in the earliest reptiles, whereas human fatherhood is hardwired into the newest areas of the brain (file image)
At the start of human evolution, mums turned to their female kin to help look after their growing horde of babies and toddlers, and human fathers were nowhere to be seen. But about 500,000 years ago, evolution caught up with men too, and dads finally began to pick up the slack.
We can still see that evolutionary time-lag today. In 2012, Israeli scientists put 15 pairs of parents of six-month-old babies in an fMRI scanner to have their brain activity assessed while they watched videos of their children playing. Both mums and dads showed activity in the areas of the brain linked to empathy and understanding others’ feelings, equally demonstrating the strong attachment they felt to their child.
But in other areas of the brain, there was a distinct difference. In mothers, the evolutionarily-ancient limbic system, which reflects the key characteristics of mothering — giving affection and nurturing — was the most active part of the brain.
By contrast, in fathers the relatively young neocortex, which is associated with ‘social cognition’, was set alight, seeming to reflect dad’s role in teaching and encouraging his child to strive towards independence.
Mothering is as old as time, present in the earliest reptiles, whereas human fatherhood is hardwired into the newest areas of the brain.
DOES MY DOG REALLY LOVE ME?
One of the amazing things about human love is our ability to extend it to other species too.
Our three dogs — Bear, Sam and Scruffy — are definitely key members of my family. But do they love me in return?
We might now have concrete neuroscientific evidence to finally lay the matter to rest. One brave professor at Emory University in the U.S. has trained dogs to lie still in an fMRI scanner, allowing him to draw conclusions about the brain of the domestic dog.
In 2016, Professor Greg Berns published his findings on 15 pet dogs, comparing brain activity when offered a food reward as opposed to a social reward, in this case, human verbal praise.
Before the scan, each dog went through training to teach them to associate the receipt of a particular reward with the appearance of a particular object. A toy car indicated the arrival of a food reward in the form of a piece of hot dog sausage; a toy horse the promise of some human verbal praise from their owners, and as a control, a hairbrush indicated no reward.
In both the case of the food and social reward there was activation in the part of the brain that underpins the unconscious elements of human love and are crammed with receptors for the ‘love hormones’, oxytocin and dopamine. But, in all cases apart from two, the activation linked to social reward was equal to, if not greater than, that linked to a food reward. These dogs loved their owners more than food.
Adapted by ALISON ROBERTS from Why We Love by Anna Machin (£18.99, Weidenfeld & Nicolson) out January 6. © Anna Machin 2022. To order a copy for £17.09 go to mailshop.co.uk/books or call 020 3176 2937. Free UK delivery on orders over £20. Offer price valid until 10/01/22.