ABOVE: Modified from © ISTOCK.COM, Dusan Stankovic


 At its most basic level, love is biological bribery. It is a set of neurochemicals which motivate you to, and reward you for,   commencing relationships with those in your life who you need to cooperate with—friends, family, lovers, the wider community—and then work to maintain them. As we will see in the next chapter, the sensations which these chemicals induce in the individual—and which we call the sensation of loving or at least liking—are there to make you feel warm, content, euphoric and encourage you not only to seek out new sources of this sensation but also motivate you to keep investing in your relationships in the long term so that the feeling, and the survival-essential cooperation, never ends.

Love: The Route to Health and Happiness

Who am I really, in isolation? I am always in relation to other people. So there is something about the people when you are with them. They are bringing out your best self. Your happiest self. The person I most enjoy being. When I am with them there is a sort of lifting of ‘Oh, not only am I feeling this joy of being with you but I am feeling the joy of being allowed to be this version of me.’ There is a self-love that happens when you are with someone else you love that you can only get by being with them. Margaret

I am sure we can all imagine how critical we were to each other in the knife-edge environments of our evolutionary past, and there are certainly areas of the world today where having the cooperation of others is still the difference between life and death. But surely here in the west, where our environment is relatively benign, and the service sector has seen fit to try and make everything we need to survive accessible from our sofa, cooperation, and in particular our closest relationships, are less about survival and more just about fun and belonging. We know what the important things for a healthy life are: exercise, a balanced diet, not smoking and maintaining a healthy weight. That’s it. We have survival cracked. But a seminal study carried out by psychologist Julianne Holt-Lunstad and her colleagues in 2010 would beg to differ. Julianne collected the data together from 148 studies which had explored rates of mortality following chronic illness—cancer, cardiovascular disease and renal failure being the most prominent—and aspects of an individual’s social network. For some studies this was the size of their network, their actual or perceived access to social support, their social isolation or loneliness, or the extent to which they were integrated into their network. Having carried out some very complex statistics to ensure she was comparing like with like, she concluded that being within a supportive social network reduced the risk of mortality by 50 percent. That places it on a par with quitting smoking, and of more influence than maintaining a healthy BMI measure.


My friends bring a support system that I know I can rely on. There is a dependability with them that I can rely on regardless. If I need cheering up, I know I can go to Bruno. If I need advice, career advice, I’ll go to David. If I need emotional, mental-health conversations, I’ll go to Nick. They provide similar but different attributes that I know I can go to. Surrounding myself with this support system means that whatever trouble or difficulty arises, I have support. Doug

Since Julianne’s study, numerous other projects have reinforced this conclusion; that having good-quality social relationships (known as social capital) is the most important factor in your health, happiness and life satisfaction. Indeed, in 2019 a group from Harvard in the US, led by Justin Rodgers, repeated Julianne’s study with the body of social-capital and health research published in the period 2007 to 2018. After reviewing 145 studies (in fact 1608 articles were published in this time but not all made it through the robust selection criteria), the Harvard team concluded that your social capital—be this the size or cohesion of your social network, your level of reciprocity or participation, your levels of trust, belonging or rate of volunteering—had a significant impact on your overall mortality or life expectancy, your risk of dying from cardiovascular disease, cancer or diabetes, the likelihood you are obese and your perception of your own health. As I write towards the end of 2020, studies finding a link between social capital and cognitive function in the elderly, adherence to HIV pre-exposure prophylaxis in at-risk gay men, reducing the risk of poor mental health following the acquisition of a disability and self-perception of health have been published. The question arises as to why being in good relationships has such a marked impact on our health? The reason is multifaceted, but explanations include the simple fact that having friends and family brings helpful resources such as money, practical care or health knowledge; that they make you feel better psychologically, which reduces the impact of stress on your body and improves your mental and physical health; or, most tantalisingly, that the neurochemicals which are released when you interact with those you love have a direct role in promoting the efficient functioning of your immune system.

‘Well, Hello, Beta-endorphin!’

I always feel better when I have seen my friends. So I saw one of them yesterday . . . I don’t get funny but I feel ‘Hmmm, I haven’t seen anyone for a couple of days.’ You get to offload . . . I need the balance of all my different friends. So mummy friends but also friends who I talk about books with and where we want to go. It is cathartic and we laugh. Life is busy and if you keep it all in your head it is unhealthy. Joan

We will learn in the next chapter that the sensation of love is underpinned by a cocktail of neurochemicals which are released when we interact with our friends and family. One of these neurochemicals—and the one I argue is the key to our ability to love in the long term—is known as beta-endorphin. Some of you may know this as the basis of your body’s natural pain-killing system or the source of the euphoric feeling which follows a bout of vigorous exercise—the phenomenon of the runner’s high—but it also appears to have a key role to play in the operation of our immune system. In 2012 endocrinologist Dipak Sarakar, who is based at Rutgers University in New Jersey, published his findings, based upon research in rats, that the mu-opioid and delta-opioid receptors had a role in the function of the natural killer cells which make up part of the mammalian immune system, ours included. The mu-opioid receptor, in particular, is the receptor in the brain upon which beta-endorphin acts, and as such Dipak’s work allows us to suggest that the release of beta-endorphin during social interaction stimulates the natural killer cells, meaning that unwanted pathogens are dealt with more efficiently than if social interaction has not occurred. This study still needs to be replicated in humans—the knocking out of some relevant genes in the rats makes this a tricky goal to achieve—but Dipak’s work offers the tantalising possibility that social interaction has an integral role to play in the operation of the body’s defence systems.

I hope it is clear by now that, whether we like it or not, we need each other and that love is the force which motivates us to overcome the difficulties of group living to cooperate at a level unmatched by any other species. We must cooperate to subsist, to learn, to raise our children, to innovate and create. We build complex and enduring networks encompassing our families, our friends, our co-workers and our lovers, which, regardless of individual differences, all follow the same pattern. Beyond the water, food and shelter that we need just to survive, our relationship with those we love has the largest impact on our health and happiness, our life satisfaction and longevity. Love has been around a long time but it is still as much about survival today as it has always been.

Excerpted from Why We Love, by Anna Machin. Copyright © 2022 by Anna Machin. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher, Pegasus Books.