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The chemistry of love

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There’s chemistry behind every step of a romantic relationship, from the initial spark to the pain of break up, as Zahra Khan discovers

Love is merely a madness, Shakespeare famously wrote. With musicians, artists and writers obsessed with the notion of love, it is not hard to understand why researchers are trying to use science to explain it. And what’s chemistry got to do with it? We even use the word to describe this intangible feeling necessary to initiate and maintain romantic connections – this ‘spark’ felt between two people. The emotions we feel when we fall in love, develop attachments, build relationships and even break up are all linked to brain chemistry. Several neuropsychologists have investigated the brain during the different stages of love and have found explicit links between brain chemicals and human behaviour.

Homo sapiens have evolved three distinct brain systems for courtship, reproduction and parenting. The human need for romantic love is not just an artist’s fantasy, it is a fundamental human need just like food, water and warmth. Love triggers a whole cocktail of neurochemicals because it is relevant to survival. There are chemical neurotransmitters and hormones that have been identified as being critical for this process such as oxytocin, vasopressin, dopamine, serotonin and testosterone.

The evidence for romantic love comes from neuroimaging and endocrinological research as well as theorising in in evolutionary human biology. Deep structures in the brain associated with reward and motivation, particularly the left ventral tegmental area, are heavily involved in the dopamine circuitry. Functional magnetic resonance imaging (FMRI) studies conducted by Helen Fisher of Indiana University, US, and colleagues indicate that romantic love is associated with dopaminergic pathways in the brain’s reward system; activating the brain’s dopamine rich regions – akin to the brain activity displayed when someone is addicted to opioids and cocaine. Hence, the longing for love can be considered a natural high.

It is generally agreed that there are at least two types of love we can identify – the first being romantic love, early stages involving passion and lust, the second more long-term, stable form of love. ‘That period of intense emotions…often associated with the early stages of a romantic relationship,’ is associated with passion and lust says Adam Bode , a romantic love and human mating researcher. ‘The sort of love that is more stable and less intense and associated with long term pair bonds is coined companionate love and these two states are related… but they are distinct and have different biological profiles.’

Pair bonding

‘Nature gave us this system, for our evolution, for romantic love and attachment,’ says Lucy Brown , a colleague of Helen Fisher and professor of neurology at the Albert Einstein College of Medicine in New York City, US. ‘This incredible basic behaviour has been studied in prairie voles . These lower mammals have shown to have similar genetic markers to humans. The ventral pallidum, the part of the brain showing high activation, is responsible for pair bonding, and we share this system for pair bonding with lower mammals,’ she explains. Pair bonding is the formation of a close relationship through courtship and sexual activity with a partner. The mating pair often produce offspring and the bond is often lifelong. Only 3% of animals pair bond and form lasting relationships. ‘Neuroscientists have been able to look very closely at the neurochemistry of [prairie voles] brain. And indeed, they did find directly in those little animals that dopamine, vasopressin and oxytocin were involved in pair bonding.’

The basic science behind romantic love has been developed from animal observations and extrapolated. ‘There are observable behaviours for pair bonding such as [animals] nest, they prefer each other, they’re aggressive towards intruders, they travel together, they groom one another,’ explains Bianca Acevedo , a research scientist at the University of California, Santa Barbara, in the US. In humans this is seen as a preference for a specific person known as romantic love.

The animal brain is always learning from reward and similarly the human brain’s reward system is highly activated in feelings of love. ‘Natural selection builds a brain that motivates you to do things that reproduce,’ comments Loretta Breuning , author of Habits of a Happy Brain . While the reproductive strategy has always been the drive behind finding a mate in the animal kingdom, humans are more complex, social beings and the need for love doesn’t always the need to produce offspring. ‘To solidify the pair bond [in animals] it coincides with having offspring and raising them… If, within a few years, the pair bond does not create offspring, they don’t generally stay together,’ Acevedo says and though our brains have evolved for this purpose, romantic love still exists without the creation of offspring – and that is what is referred to as attachment. The brain system has developed over evolution not just for survival, but also through the need to protect each other.

Brown’s research with Fisher hypothesised that romantic love was a developed form of a mammalian drive, to pursue preferred mates. ‘Then we looked at the data, we saw that the activation in the brain for everybody was in this dopamine-rich area of the brain stem – not in the higher parts of the cognitive human brain. But in these lower parts, where reflexes are controlled, reflexes, like swallowing, even breathing,’ says Brown.

Love is a drug

Our neural pathways are built from past experiences with these ‘happy’ chemicals that determines what turns them on and our brains are designed to recognise opportunity and anticipate reward. The initial stage of love is usually lust. That is, the instant attraction one feels in the presence of another – love at first sight, even. Individuals in this phase experience heightened dopamine and testosterone.

‘Testosterone plays a role in sexual desire and sex drive… one of the theories was that testosterone in females increases to make them want to engage in more sex, and testosterone levels in males reduced in an attempt to make them less interested in sex with multiple partners,’ says Bode. Along with oestrogen and dopamine, these chemicals are very important for our sex drive. Dopamine is associated with arousal and increased focus on the loved one. And because the drive for sex is a basic drive like hunger and thirst, the dopamine system in the hypothalamus is always engaged in romantic love.

Dopamine is the excitement you feel when you’re about to meet a need giving you an indicator of where to invest your energy because the need is being met – just like food and water. ‘And dopamine is released when you say “Yes, this is a good opportunity,”’ says Breuning of when you first meet a potential partner. When we find an ideal person, we are biologically rewarded through dopamine to find that person both interesting and attractive.

For those couples that maintain romantic love, they still get their fix of dopamine ‘when they see that person, when they think about them, their brain lights up, their dopamine centres light up’, says Acevedo. In the longer term, where people go about their daily life and return to their mate, the individual is not solely concentrating on their partner and so this attachment phase is much calmer. Functional MRI studies show that this phase involves chemicals like oxytocin and vasopressin, which allow a relationship to survive past the first few dates. The literature has emphasised oxytocin, often referring to it as the love hormone.

‘About 220 million years ago, in conjunction with evolution, that molecule [oxytocin] gave us a whole lot of benefits,’ says Sue Carter , a biologist at Indiana University in the US. It underlies the chemistry of the attachment of a mother with their newborn. ‘We have oxytocin, and we have a more primitive molecule, a kind of stress hormone phase suppressant that has many other functions – vasopressin.’ Oxytocin and vasopressin work combinatorically and have different receptors but can bind to each other’s receptors. Both oxytocin and vasopressin are being released in the falling in love experience, but these chemicals are especially important for staying in love. Oxytocin is responsible for making us feel good when we bond – it is the urge for protection which can be manifested in several ways and while motivations differ, oxytocin is triggered when you feel protected, for example.

Oxytocin is also important for various behaviours not just for pair bonds, but for trust and empathy, and becomes very significant in a ‘healthy relationship’, says Carter, adding that if vasopressin is the dominant molecule it can result in obsessive, one-sided relationship. The relationship needs to be balanced with a reasonable amount of oxytocin, helping to get the considerable health benefits of good relationships, such as living longer and having less disease. ‘In this way oxytocin is our friend but is not sufficient on its own. We have this beautiful chemistry with these two molecules and then a very large arsenal of other chemicals like dopamine, serotonin, opioids etc,’ adds Carter.

A recent study looked at prairie voles and found that when removing the oxytocin receptors, they still formed pair bonds so it is possible that oxytocin may not be necessary for pair bonding, but there are very few explicit studies on romantic love and oxytocin. Bode says that while oxytocin makes us feel happy and content when we bond, ‘the pleasure we actually gain from these relationships is dictated by opioids’. Endorphin is a natural opioid in the body and is mostly designed to relieve pain but can also be triggered when you laugh. ‘There’s something called the brain opioid theory of social attachment , which argues that the opioid system is actually the intricate system involved in all sorts of close social relationships,’ he adds, stating that endorphins might be better described as the love drug that give us our sense of calmness and pleasure.

Can we fix a broken heart?

Some people call love a drug, and it does work on the same chemistry that other drugs work on. When you take psychedelics, you pour out both serotonin and oxytocin and so the analogies between romantic love and substance dependence are valid. When you’re no longer connected to the person you’re in love with, you can suffer from withdrawal. ‘This is a withdrawal system… pretty much identical to the one you see with opioids,’ says Carter.

It’s so important to form a pair bond for humans that we try to do everything to save that relationship. Dopamine is still a major player in controlling the feelings from a break-up. When a person experiences heartbreak they are overwhelmed by the activation of their dopamine system – they are craving that person. This has been observed in subjects who, after being shown pictures of their ex-partners, had their reward system go into overdrive and so the heartbreak process can be described as a natural addiction. It’s the distress area that’s active in the brain – we feel the distress of physical pain.

Other behaviours related to threat and fears start to emerge and some individuals can suffer unpleasant physiological symptoms such as depression. While painkillers and antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs), have been shown to relieve some of the grief or feelings of inadequacy, serotonin withdrawal symptoms can happen; ‘SSRIs in many people inhibit both emotional behaviours and sexual responses,’ warns Carter. Withdrawal from these drugs can have effects of creating a dependency that will later have an impact on the individual’s ability to fall in love again.

The disappointment associated with heartbreak is accompanied by a big release of threat chemicals. Stressful moments are associated with elevated cortisol. Cortisol, linked with stress, notifies the brain of a threat – it’s released when you fail and tells the brain that your efforts are not getting a reward. During heartbreak you give up on this target and ‘it builds a new neural pathway that causes your brain to think negatively about that target instead of positively’, says Breuling. This has been seen in studies by Brown. ‘When our subjects were looking at this picture of the person who had dumped them, their brains were also trying to - in some of the cognitive areas – weight the negatives and positives…trying to make something better of this.’

However, falling out of love is very different to breaking up. ‘You may still feel warmth and friendship towards the person, and you still may love them, but that high isn’t there anymore. The activations… tend to be seen in oxytocin- and serotonin-rich regions of the brain, but not necessarily the dopamine-rich areas of the brain,’ Acevedo points out, analogous to the brain activity when seeing images of close friends and family.

Hopeful future

Considering how integral love is to our lives, research in the field of romantic love is in its infancy with a lot of uncharted territory in the neuroscience area. Humans are extremely variable, and how much they use the reward system for love and attachment is partly genetic and a lot comes from their experience. The lack of defined parameters for assessment makes this research area challenging yet the potential is huge. Understanding these chemicals and how they relate to different emotional states can allow us to deal with ‘broken hearts’ at a neurochemical level, as well as accelerating the process of finding love but to date, we know very little about the brain.

Nonetheless, there is strong scientific evidence for the idea of ‘chemistry’ – ‘the brain has told us something about ourselves as humans, it is naturally occurring but a very strong drive…It’s not just an emotion that you have control over,’ explains Brown, adding that this basic drive for sticking to someone is a part of every human, regardless of their sexual orientation.

There are strong motivations for pursuing the subject as Bode points out. ‘Romantic love is the basis for romantic relationship formation and family formation throughout much of the world. And it is something that can bring both great sorrow and great joy. And to that extent, I think it’s intrinsically valuable to understand that things that bring us sorrow and joy.’

Zahra Khan is a science writer based in London, UK

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The Chemistry of Love: Why Do We Fall in Love?

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The biochemistry of love: an oxytocin hypothesis

C Sue Carter

1 C Sue Carter and Stephen W Porges are research scientists at the Research Triangle Institute International in Research Triangle Park, North Carolina, USA

Stephen W Porges

Love is deeply biological. It pervades every aspect of our lives and has inspired countless works of art. Love also has a profound effect on our mental and physical state. A ‘broken heart’ or a failed relationship can have disastrous effects; bereavement disrupts human physiology and might even precipitate death. Without loving relationships, humans fail to flourish, even if all of their other basic needs are met.

As such, love is clearly not ‘just’ an emotion; it is a biological process that is both dynamic and bidirectional in several dimensions. Social interactions between individuals, for example, trigger cognitive and physiological processes that influence emotional and mental states. In turn, these changes influence future social interactions. Similarly, the maintenance of loving relationships requires constant feedback through sensory and cognitive systems; the body seeks love and responds constantly to interaction with loved ones or to the absence of such interaction.

Without loving relationships, humans fail to flourish, even if all of their other basic needs are met

Although evidence exists for the healing power of love, it is only recently that science has turned its attention to providing a physiological explanation. The study of love, in this context, offers insight into many important topics including the biological basis of interpersonal relationships and why and how disruptions in social bonds have such pervasive consequences for behaviour and physiology. Some of the answers will be found in our growing knowledge of the neurobiological and endocrinological mechanisms of social behaviour and interpersonal engagement.

Nothing in biology makes sense except in the light of evolution. Theodosius Dobzhansky's famous dictum also holds true for explaining the evolution of love. Life on Earth is fundamentally social: the ability to interact dynamically with other living organisms to support mutual homeostasis, growth and reproduction evolved early. Social interactions are present in primitive invertebrates and even among prokaryotes: bacteria recognize and approach members of their own species. Bacteria also reproduce more successfully in the presence of their own kind and are able to form communities with physical and chemical characteristics that go far beyond the capabilities of the individual cell [ 1 ].

As another example, insect species have evolved particularly complex social systems, known as ‘eusociality’. Characterized by a division of labour, eusociality seems to have evolved independently at least 11 times. Research in honey-bees indicates that a complex set of genes and their interactions regulate eusociality, and that these resulted from an “accelerated form of evolution” [ 2 ]. In other words, molecular mechanisms favouring high levels of sociality seem to be on an evolutionary fast track.

The evolutionary pathways that led from reptiles to mammals allowed the emergence of the unique anatomical systems and biochemical mechanisms that enable social engagement and selectively reciprocal sociality. Reptiles show minimal parental investment in offspring and form non-selective relationships between individuals. Pet owners might become emotionally attached to their turtle or snake, but this relationship is not reciprocal. By contrast, many mammals show intense parental investment in offspring and form lasting bonds with the offspring. Several mammalian species—including humans, wolves and prairie voles—also develop long-lasting, reciprocal and selective relationships between adults, with several features of what humans experience as ‘love’. In turn, these reciprocal interactions trigger dynamic feedback mechanisms that foster growth and health.

Of course, human love is more complex than simple feedback mechanisms. Love might create its own reality. The biology of love originates in the primitive parts of the brain—the emotional core of the human nervous system—that evolved long before the cerebral cortex. The brain of a human ‘in love’ is flooded with sensations, often transmitted by the vagus nerve, creating much of what we experience as emotion. The modern cortex struggles to interpret the primal messages of love, and weaves a narrative around incoming visceral experiences, potentially reacting to that narrative rather than reality.

Science & Society Series on Sex and Science

Sex is the greatest invention of all time: not only has sexual reproduction facilitated the evolution of higher life forms, it has had a profound influence on human history, culture and society. This series explores our attempts to understand the influence of sex in the natural world, and the biological, medical and cultural aspects of sexual reproduction, gender and sexual pleasure.

It also is helpful to realize that mammalian social behaviour is supported by biological components that were repurposed or co-opted over the course of mammalian evolution, eventually allowing lasting relationships between adults. One element that repeatedly features in the biochemistry of love is the neuropeptide oxytocin. In large mammals, oxytocin adopts a central role in reproduction by helping to expel the big-brained baby from the uterus, ejecting milk and sealing a selective and lasting bond between mother and offspring [ 3 ]. Mammalian offspring crucially depend on their mother's milk for some time after birth. Human mothers also form a strong and lasting bond with their newborns immediately after birth, in a time period that is essential for the nourishment and survival of the baby. However, women who give birth by caesarean section without going through labour, or who opt not to breast-feed, still form a strong emotional bond with their children. Furthermore, fathers, grandparents and adoptive parents also form lifelong attachments to children. Preliminary evidence suggests that simply the presence of an infant releases oxytocin in adults [ 4 , 5 ]. The baby virtually ‘forces’ us to love it ( Fig 1 ).

As a one-year-old Mandrill infant solicits attention, she gains eye contact with her mother. © 2012 Jessie Williams.

Emotional bonds can also form during periods of extreme duress, especially when the survival of one individual depends on the presence and support of another. There is also evidence that oxytocin is released in response to acutely stressful experiences, possibly serving as hormonal ‘insurance’ against overwhelming stress. Oxytocin might help to assure that parents and others will engage with and care for infants, to stabilize loving relationships and to ensure that, in times of need, we will seek and receive support from others.

The case for a major role for oxytocin in love is strong, but until recently has been based largely on extrapolation from research on parental behaviour [ 4 ] or social behaviours in animals [ 5 , 6 ]. However, human experiments have shown that intranasal delivery of oxytocin can facilitate social behaviours, including eye contact and social cognition [ 7 ]—behaviours that are at the heart of love.

Of course, oxytocin is not the molecular equivalent of love. It is just one important component of a complex neurochemical system that allows the body to adapt to highly emotive situations. The systems necessary for reciprocal social interactions involve extensive neural networks through the brain and autonomic nervous system that are dynamic and constantly changing during the lifespan of an individual. We also know that the properties of oxytocin are not predetermined or fixed. Oxytocin's cellular receptors are regulated by other hormones and epigenetic factors. These receptors change and adapt on the basis of life experiences. Both oxytocin and the experience of love change over time. In spite of limitations, new knowledge of the properties of oxytocin has proven useful in explaining several enigmatic features of love.

To dissect the anatomy and chemistry of love, scientists needed a biological equivalent of the Rosetta stone. Just as the actual stone helped linguists to decipher an archaic language by comparison to a known one, animal models are helping biologists draw parallels between ancient physiology and contemporary behaviours. Studies of socially monogamous mammals that form long-lasting social bonds, such as prairie voles, are helping scientists to understand the biology of human social behaviour.

The modern cortex struggles to interpret the primal messages of love, and weaves a narrative around incoming visceral experiences, potentially reacting to that narrative rather than reality

Research in voles indicates that, as in humans, oxytocin has a major role in social interactions and parental behaviour [ 5 , 6 , 8 ]. Of course, oxytocin does not act alone. Its release and actions depend on many other neurochemicals, including endogenous opioids and dopamine [ 9 ]. Particularly important to social bonding are the interactions between oxytocin and a related peptide, vasopressin. The systems regulated by oxytocin and vasopressin are sometimes redundant. Both peptides are implicated in behaviours that require social engagement by either males or females, such as huddling over an infant [ 5 ]. It was necessary in voles, for example, to block both oxytocin and vasopressin receptors to induce a significant reduction in social engagement either among adults or between adults and infants. Blocking only one of these two receptors did not eliminate social approach or contact. However, antagonists for either the oxytocin or vasopressin receptor inhibited the selective sociality, which is essential for the expression of a social bond [ 10 , 11 ]. If we accept selective social bonds, parenting and mate protection as proxies for love in humans, research in animals supports the hypothesis that oxytocin and vasopressin interact to allow the dynamic behavioural states and behaviours necessary for love.

Oxytocin and vasopressin have shared functions, but they are not identical in their actions. The specific behavioural roles of oxytocin and vasopressin are especially difficult to untangle because they are components of an integrated neural network with many points of intersection. Moreover, the genes that regulate the production of oxytocin and vasopressin are located on the same chromosome, possibly allowing a co-ordinated synthesis or release of these peptides. Both peptides can bind to, and have, antagonist or agonist effects on each other's receptors. Furthermore, the pathways necessary for reciprocal social behaviour are constantly adapting: these peptides and the systems that they regulate are always in flux.

In spite of these difficulties, some of the functions of oxytocin and vasopressin have been identified. Vasopressin is associated with physical and emotional mobilization, and supports vigilance and behaviours needed for guarding a partner or territory [ 6 ], as well as other forms of adaptive self-defence [ 12 ]. Vasopressin might also protect against ‘shutting down’ physiologically in the face of danger. In many mammalian species, mothers behave agonistically in defence of their young, possibly through the interactive actions of vasopressin and oxytocin [ 13 ]. Before mating, prairie voles are generally social, even towards strangers. However, within approximately one day of mating, they begin to show high levels of aggression towards intruders [ 14 ], possibly serving to protect or guard a mate, family or territory. This mating-induced aggression is especially obvious in males.

By contrast, oxytocin is associated with immobility without fear. This includes relaxed physiological states and postures that allow birth, lactation and consensual sexual behaviour. Although not essential for parenting, the increase of oxytocin associated with birth and lactation might make it easier for a woman to be less anxious around her newborn and to experience and express loving feelings for her child [ 15 ]. In highly social species such as prairie voles, and presumably in humans, the intricate molecular dances of oxytocin and vasopressin fine-tune the coexistence of care-taking and protective aggression.

The biology of fatherhood is less well studied. However, male care of offspring also seems to rely on both oxytocin and vasopressin [ 5 ]; even sexually naive male prairie voles show spontaneous parental behaviour in the presence of an infant [ 14 ]. However, the stimuli from infants or the nature of the social interactions that release oxytocin and vasopressin might differ between the sexes [ 4 ].

Parental care and support in a safe environment are particularly important for mental health in social mammals, including humans and prairie voles. Studies of rodents and lactating women suggest that oxytocin has the capacity to modulate the behavioural and autonomic distress that typically follows separation from a mother, child or partner, reducing defensive behaviours and thereby supporting growth and health [ 6 ].

During early life in particular, trauma or neglect might produce behaviours and emotional states in humans that are socially pathological. As the processes involved in creating social behaviours and social emotions are delicately balanced, they might be triggered in inappropriate contexts, leading to aggression towards friends or family. Alternatively, bonds might be formed with prospective partners who fail to provide social support or protection.

Males seem to be especially vulnerable to the negative effects of early experiences, possibly explaining their increased sensitivity to developmental disorders. Autism spectrum disorders, for example, defined in part by atypical social behaviours, are estimated to be three to ten times more common in males than females. The implication of sex differences in the nervous system, and in response to stressful experiences for social behaviour, is only slowly becoming apparent [ 8 ]. Both males and females produce vasopressin and oxytocin and are capable of responding to both hormones. However, in brain regions that are involved in defensive aggression, such as the extended amygdala and lateral septum, the production of vasopressin is androgen-dependent. Thus, in the face of a threat, males might experience higher central levels of vasopressin.

In highly social species […] the intricate molecular dances of oxytocin and vasopressin fine-tune the coexistence of care-taking and protective aggression

Oxytocin and vasopressin pathways, including the peptides and their receptors, are regulated by coordinated genetic, hormonal and epigenetic factors that influence the adaptive and behavioural functions of these peptides across the animal's lifespan. As a result, the endocrine and behavioural consequences of stress or a challenge might be different for males and females [ 16 ]. When unpaired prairie voles were exposed to an intense but brief stressor, such as a few minutes of swimming or injection of the adrenal hormone corticosterone, the males (but not females) quickly formed new pair bonds. These and other experiments suggest that males and females have different coping strategies, and possibly experience both stressful experiences and even love in ways that are gender-specific.

Love is an epigenetic phenomenon: social behaviours, emotional attachment to others and long-lasting reciprocal relationships are plastic and adaptive and so is the biology on which they are based. Because of this and the influence on parental behaviour and physiology, the impact of an early experience can pass to the next generation [ 17 ]. Infants of traumatized or highly stressed parents might be chronically exposed to vasopressin, either through their own increased production of the peptide, or through higher levels of vasopressin in maternal milk. Such increased exposure could sensitize the infant to defensive behaviours or create a life-long tendency to overreact to threat. On the basis of research in rats, it seems, that in response to adverse early experiences or chronic isolation, the genes for vasopressin receptors can become upregulated [ 18 ], leading to an increased sensitivity to acute stressors or anxiety that might persist throughout life.

…oxytocin exposure early in life not only regulates our ability to love and form social bonds, it also has an impact on our health and well-being

Epigenetic programming triggered by early life experiences is adaptive in allowing neuroendocrine systems to project and plan for future behavioural demands. However, epigenetic changes that are long-lasting can also create atypical social or emotional behaviours [ 17 ] that might be more likely to surface in later life, and in the face of social or emotional challenges. Exposure to exogenous hormones in early life might also be epigenetic. Prairie voles, for example, treated with vasopressin post-natally were more aggressive later in life, whereas those exposed to a vasopressin antagonist showed less aggression in adulthood. Conversely, the exposure of infants to slightly increased levels of oxytocin during development increased the tendency to show a pair bond in voles. However, these studies also showed that a single exposure to a higher level of oxytocin in early life could disrupt the later capacity to pair bond [ 8 ]. There is little doubt that either early social experiences or the effects of developmental exposure to these neuropeptides can potentially have long-lasting effects on behaviour. Both parental care and exposure to oxytocin in early life can permanently modify hormonal systems, altering the capacity to form relationships and influence the expression of love across the lifespan. Our preliminary findings in voles suggest further that early life experience affects the methylation of the oxytocin receptor gene and its expression [ 19 ]. Thus, we can plausibly argue that “love is epigenetic.”

Given the power of positive social experiences, it is not surprising that a lack of social relationships might also lead to alterations in behaviour and concurrently changes in oxytocin and vasopressin pathways. We have found that social isolation reduced the expression of the gene for the oxytocin receptor, and at the same time increased the expression of genes for the vasopressin peptide (H.P. Nazarloo and C.S. Carter, unpublished data). In female prairie voles, isolation was also accompanied by an increase in blood levels of oxytocin, possibly as a coping mechanism. However, over time, isolated prairie voles of both sexes showed increases in measures of depression, anxiety and physiological arousal, and these changes were seen even when endogenous oxytocin was elevated. Thus, even the hormonal insurance provided by endogenous oxytocin in the face of the chronic stress of isolation was not sufficient to dampen the consequences of living alone. Predictably, when isolated voles were given additional exogenous oxytocin this treatment restored many of these functions to normal [ 20 ].

On the basis of such encouraging findings, dozens of ongoing clinical trials are attempting to examine the therapeutic potential of oxytocin in disorders ranging from autism to heart disease (Clinicaltrials.gov). Of course, as in voles, the effects are likely to depend on the history of the individual and the context, and to be dose-dependent. With power comes responsibility, and the power of oxytocin needs to be respected.

Although research has only begun to examine the physiological effects of these peptides beyond social behaviour, there is a wealth of new evidence indicating that oxytocin influences physiological responses to stress and injury. Thus, oxytocin exposure early in life not only regulates our ability to love and form social bonds, it also has an impact on our health and well-being. Oxytocin modulates the hypothalamic–pituitary adrenal (HPA) axis, especially in response to disruptions in homeostasis [ 6 ], and coordinates demands on the immune system and energy balance. Long-term secure relationships provide emotional support and downregulate reactivity of the HPA axis, whereas intense stressors, including birth, trigger activation of the HPA axis and sympathetic nervous system. The ability of oxytocin to regulate these systems probably explains the exceptional capacity of most women to cope with the challenges of child-birth and child-rearing. The same molecules that allow us to give and receive love, also link our need for others with health and well-being.

The protective effects of positive sociality seem to rely on the same cocktail of hormones that carry a biological message of ‘love’ throughout the body

Of course, love is not without danger. The behaviours and strong emotions triggered by love might leave us vulnerable. Failed relationships can have devastating, even deadly, effects. In ‘modern’ societies humans can survive, at least after childhood, with little or no human contact. Communication technology, social media, electronic parenting and many other technological advances of the past century might place both children and adults at risk for social isolation and disorders of the autonomic nervous system, including deficits in their capacity for social engagement and love [ 21 ].

Social engagement actually helps us to cope with stress. The same hormones and areas of the brain that increase the capacity of the body to survive stress also enable us to better adapt to an ever-changing social and physical environment. Individuals with strong emotional support and relationships are more resilient in the face of stressors than those who feel isolated or lonely. Lesions in bodily tissues, including the brain, heal more quickly in animals that are living socially compared with those in isolation [ 22 ]. The protective effects of positive sociality seem to rely on the same cocktail of hormones that carry a biological message of ‘love’ throughout the body.

As only one example, the molecules associated with love have restorative properties, including the ability to literally heal a ‘broken heart’. Oxytocin receptors are expressed in the heart, and precursors for oxytocin seem to be crucial for the development of the fetal heart [ 23 ]. Oxytocin exerts protective and restorative effects in part through its capacity to convert undifferentiated stem cells into cardiomyocytes. Oxytocin can facilitate adult neurogenesis and tissue repair, especially after a stressful experience. We know that oxytocin has direct anti-inflammatory and anti-oxidant properties in in vitro models of atherosclerosis [ 24 ]. The heart seems to rely on oxytocin as part of a normal process of protection and self-healing.

A life without love is not a life fully lived. Although research into mechanisms through which love protects us against stress and disease is in its infancy, this knowledge will ultimately increase our understanding of the way that our emotions have an impact on health and disease. We have much to learn about love and much to learn from love.

Acknowledgments

Discussions of ‘love and forgiveness’ with members of the Fetzer Institute's Advisory Council on Natural Sciences led to this essay and are gratefully acknowledged. We especially appreciate thoughtful editorial input from James Harris. Studies from the authors' laboratories were sponsored by the National Institutes of Health. We also express our gratitude for this support to our colleagues whose input and hard work informed the ideas expressed in this article.

The authors declare that they have no conflict of interest.

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Sure, your heart thumps, but let’s look at what’s happening physically and psychologically

“They gave each other a smile with a future in it.” — Ring Lardner

Love’s warm squishiness seems a thing far removed from the cold, hard reality of science. Yet the two do meet, whether in lab tests for surging hormones or in austere chambers where MRI scanners noisily thunk and peer into brains that ignite at glimpses of their soulmates.

When it comes to thinking deeply about love, poets, philosophers, and even high school boys gazing dreamily at girls two rows over have a significant head start on science. But the field is gamely racing to catch up.

One database of scientific publications turns up more than 6,600 pages of results in a search for the word “love.” The National Institutes of Health (NIH) is conducting 18 clinical trials on it (though, like love itself, NIH’s “love” can have layered meanings, including as an acronym for a study of Crohn’s disease). Though not normally considered an intestinal ailment, love is often described as an illness, and the smitten as lovesick. Comedian George Burns once described love as something like a backache: “It doesn’t show up on X-rays, but you know it’s there.”

Richard Schwartz , associate professor of psychiatry at Harvard Medical School (HMS) and a consultant to McLean and Massachusetts General (MGH) hospitals, says it’s never been proven that love makes you physically sick, though it does raise levels of cortisol, a stress hormone that has been shown to suppress immune function.

Love also turns on the neurotransmitter dopamine, which is known to stimulate the brain’s pleasure centers. Couple that with a drop in levels of serotonin — which adds a dash of obsession — and you have the crazy, pleasing, stupefied, urgent love of infatuation.

It’s also true, Schwartz said, that like the moon — a trigger of its own legendary form of madness — love has its phases.

“It’s fairly complex, and we only know a little about it,” Schwartz said. “There are different phases and moods of love. The early phase of love is quite different” from later phases.

During the first love-year, serotonin levels gradually return to normal, and the “stupid” and “obsessive” aspects of the condition moderate. That period is followed by increases in the hormone oxytocin, a neurotransmitter associated with a calmer, more mature form of love. The oxytocin helps cement bonds, raise immune function, and begin to confer the health benefits found in married couples, who tend to live longer, have fewer strokes and heart attacks, be less depressed, and have higher survival rates from major surgery and cancer.

Schwartz has built a career around studying the love, hate, indifference, and other emotions that mark our complex relationships. And, though science is learning more in the lab than ever before, he said he still has learned far more counseling couples. His wife and sometime collaborator, Jacqueline Olds , also an associate professor of psychiatry at HMS and a consultant to McLean and MGH, agrees.

Spouses Richard Schwartz and Jacqueline Olds, both associate professors of psychiatry, have collaborated on a book about marriage.

Stephanie Mitchell/Harvard Staff Photographer

More knowledge, but struggling to understand

“I think we know a lot more scientifically about love and the brain than we did a couple of decades ago, but I don’t think it tells us very much that we didn’t already know about love,” Schwartz said. “It’s kind of interesting, it’s kind of fun [to study]. But do we think that makes us better at love, or helping people with love? Probably not much.”

Love and companionship have made indelible marks on Schwartz and Olds. Though they have separate careers, they’re separate together, working from discrete offices across the hall from each other in their stately Cambridge home. Each has a professional practice and independently trains psychiatry students, but they’ve also collaborated on two books about loneliness and one on marriage. Their own union has lasted 39 years, and they raised two children.

“I think we know a lot more scientifically about love and the brain than we did a couple of decades ago … But do we think that makes us better at love, or helping people with love? Probably not much.” Richard Schwartz, associate professor of psychiatry, Harvard Medical School

“I have learned much more from doing couples therapy, and being in a couple’s relationship” than from science, Olds said. “But every now and again, something like the fMRI or chemical studies can help you make the point better. If you say to somebody, ‘I think you’re doing this, and it’s terrible for a relationship,’ they may not pay attention. If you say, ‘It’s corrosive, and it’s causing your cortisol to go way up,’ then they really sit up and listen.”

A side benefit is that examining other couples’ trials and tribulations has helped their own relationship over the inevitable rocky bumps, Olds said.

“To some extent, being a psychiatrist allows you a privileged window into other people’s triumphs and mistakes,” Olds said. “And because you get to learn from them as they learn from you, when you work with somebody 10 years older than you, you learn what mistakes 10 years down the line might be.”

People have written for centuries about love shifting from passionate to companionate, something Schwartz called “both a good and a sad thing.” Different couples experience that shift differently. While the passion fades for some, others keep its flames burning, while still others are able to rekindle the fires.

“You have a tidal-like motion of closeness and drifting apart, closeness and drifting apart,” Olds said. “And you have to have one person have a ‘distance alarm’ to notice the drifting apart so there can be a reconnection … One could say that in the couples who are most successful at keeping their relationship alive over the years, there’s an element of companionate love and an element of passionate love. And those each get reawakened in that drifting back and forth, the ebb and flow of lasting relationships.”

Children as the biggest stressor

Children remain the biggest stressor on relationships, Olds said, adding that it seems a particular problem these days. Young parents feel pressure to raise kids perfectly, even at the risk of their own relationships. Kids are a constant presence for parents. The days when child care consisted of the instruction “Go play outside” while mom and dad reconnected over cocktails are largely gone.

When not hovering over children, America’s workaholic culture, coupled with technology’s 24/7 intrusiveness, can make it hard for partners to pay attention to each other in the evenings and even on weekends. It is a problem that Olds sees even in environments that ought to know better, such as psychiatry residency programs.

“There are all these sweet young doctors who are trying to have families while they’re in residency,” Olds said. “And the residencies work them so hard there’s barely time for their relationship or having children or taking care of children. So, we’re always trying to balance the fact that, in psychiatry, we stand for psychological good health, but [in] the residency we run, sometimes we don’t practice everything we preach.”

“There is too much pressure … on what a romantic partner should be. They should be your best friend, they should be your lover, they should be your closest relative, they should be your work partner, they should be the co-parent, your athletic partner. … Of course everybody isn’t able to quite live up to it.” Jacqueline Olds, associate professor of psychiatry, Harvard Medical School

All this busy-ness has affected non-romantic relationships too, which has a ripple effect on the romantic ones, Olds said. A respected national social survey has shown that in recent years people have gone from having three close friends to two, with one of those their romantic partner.

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“Often when you scratch the surface … the second [friend] lives 3,000 miles away, and you can’t talk to them on the phone because they’re on a different time schedule,” Olds said. “There is too much pressure, from my point of view, on what a romantic partner should be. They should be your best friend, they should be your lover, they should be your closest relative, they should be your work partner, they should be the co-parent, your athletic partner. There’s just so much pressure on the role of spouse that of course everybody isn’t able to quite live up to it.”

Since the rising challenges of modern life aren’t going to change soon, Schwartz and Olds said couples should try to adopt ways to fortify their relationships for life’s long haul. For instance, couples benefit from shared goals and activities, which will help pull them along a shared life path, Schwartz said.

“You’re not going to get to 40 years by gazing into each other’s eyes,” Schwartz said. “I think the fact that we’ve worked on things together has woven us together more, in good ways.”

Maintain curiosity about your partner

Also important is retaining a genuine sense of curiosity about your partner, fostered both by time apart to have separate experiences, and by time together, just as a couple, to share those experiences. Schwartz cited a study by Robert Waldinger, clinical professor of psychiatry at MGH and HMS, in which couples watched videos of themselves arguing. Afterwards, each person was asked what the partner was thinking. The longer they had been together, the worse they actually were at guessing, in part because they thought they already knew.

“What keeps love alive is being able to recognize that you don’t really know your partner perfectly and still being curious and still be exploring,” Schwartz said. “Which means, in addition to being sure you have enough time and involvement with each other — that that time isn’t stolen — making sure you have enough separateness that you can be an object of curiosity for the other person.”

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2.5: Biochemistry of Love

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By Sue Carter and Stephen Porges

University of North Carolina, Northeastern University - Boston

Love is deeply biological. It pervades every aspect of our lives and has inspired countless works of art. Love also has a profound effect on our mental and physical state. A “broken heart” or a failed relationship can have disastrous effects; bereavement disrupts human physiology and may even precipitate death. Without loving relationships, humans fail to flourish, even if all of their other basic needs are met. As such, love is clearly not “just” an emotion; it is a biological process that is both dynamic and bidirectional in several dimensions. Social interactions between individuals, for example, trigger cognitive and physiological processes that influence emotional and mental states. In turn, these changes influence future social interactions. Similarly, the maintenance of loving relationships requires constant feedback through sensory and cognitive systems; the body seeks love and responds constantly to interactions with loved ones or to the absence of such interactions. The evolutionary principles and ancient hormonal and neural systems that support the beneficial and healing effects of loving relationships are described here.

learning objectives

• Understand the role of Oxytocin in social behaviors.
• Articulate the functional differences between Vasopressin and Oxytocin.
• List sex differences in reaction to stress.

Introduction

Although evidence exists for the healing power of love, only recently has science turned its attention to providing a physiological explanation for love. The study of love in this context offers insight into many important topics, including the biological basis of interpersonal relationships and why and how disruptions in social bonds have such pervasive consequences for behavior and physiology. Some of the answers will be found in our growing knowledge of the neurobiological and endocrinological mechanisms of social behavior and interpersonal engagement.

The evolution of social behavior

Nothing in biology makes sense except in the light of evolution. Theodosius Dobzhansky’s famous dictum also holds true for explaining the evolution of love. Life on earth is fundamentally social: The ability to dynamically interact with other living organisms to support mutual homeostasis, growth, and reproduction evolved very early. Social interactions are present in primitive invertebrates and even among prokaryotes: Bacteria recognize and approach members of their own species. Bacteria also reproduce more successfully in the presence of their own kind and are able to form communities with physical and chemical characteristics that go far beyond the capabilities of the individual cell (Ingham & Ben-Jacob, 2008).

As another example, various insect species have evolved particularly complex social systems, known as eusociality. Characterized by a division of labor, eusociality appears to have evolved independently at least 11 times in insects. Research on honeybees indicates that a complex set of genes and their interactions regulate eusociality, and that these resulted from an “accelerated form of evolution” (Woodard et al., 2011). In other words, molecular mechanisms favoring high levels of sociality seem to be on an evolutionary fast track.

The evolutionary pathways that led from reptiles to mammals allowed the emergence of the unique anatomical systems and biochemical mechanisms that enable social engagement and selectively reciprocal sociality. Reptiles show minimal parental investment in offspring and form nonselective relationships between individuals. Pet owners may become emotionally attached to their turtle or snake, but this relationship is not reciprocal. In contrast, most mammals show intense parental investment in offspring and form lasting bonds with their children. Many mammalian species—including humans, wolves, and prairie voles—also develop long-lasting, reciprocal, and selective relationships between adults, with several features of what humans experience as “love.” In turn, these reciprocal interactions trigger dynamic feedback mechanisms that foster growth and health.

What is love? An evolutionary and physiological perspective

Human love is more complex than simple feedback mechanisms. Love may create its own reality. The biology of love originates in the primitive parts of the brain—the emotional core of the human nervous system—which evolved long before the cerebral cortex. The brain “in love” is flooded with vague sensations, often transmitted by the vagus nerve , and creating much of what we experience as emotion. The modern cortex struggles to interpret love’s primal messages, and weaves a narrative around incoming visceral experiences, potentially reacting to that narrative rather than to reality. It also is helpful to realize that mammalian social behavior is supported by biological components that were repurposed or co-opted over the course of mammalian evolution, eventually permitting lasting relationships between adults.

Is there a hormone of love and other relationships?

One element that repeatedly appears in the biochemistry of love is the neuropeptide oxytocin . In large mammals, oxytocin adopts a central role in reproduction by helping to expel the big-brained baby from the uterus, ejecting milk and sealing a selective and lasting bond between mother and offspring (Keverne, 2006). Mammalian offspring crucially depend on their mother’s milk for some time after birth. Human mothers also form a strong and lasting bond with their newborns immediately after birth, in a time period that is essential for the nourishment and survival of the baby. However, women who give birth by cesarean section without going through labor, or who opt not to breastfeed, are still able to form a strong emotional bond with their children. Furthermore, fathers, grandparents, and adoptive parents also form lifelong attachments to children. Preliminary evidence suggests that the simple presence of an infant can release oxytocin in adults as well (Feldman, 2012; Kenkel et al., 2012). The baby virtually forces us to love it.

The case for a major role for oxytocin in love is strong, but until recently was based largely on extrapolation from research on parental behavior (Feldman, 2012) or social behaviors in animals (Carter, 1998; Kenkel et al., 2012). However, recent human experiments have shown that intranasal delivery of oxytocin can facilitate social behaviors, including eye contact and social cognition (Meyer-Lindenberg, Domes, Kirsch, & Heinrichs, 2011)—behaviors that are at the heart of love.

Of course, oxytocin is not the molecular equivalent of love. Rather, it is just one important component of a complex neurochemical system that allows the body to adapt to highly emotional situations. The systems necessary for reciprocal social interactions involve extensive neural networks through the brain and autonomic nervous system that are dynamic and constantly changing across the life span of an individual. We also now know that the properties of oxytocin are not predetermined or fixed. Oxytocin’s cellular receptors are regulated by other hormones and epigenetic factors. These receptors change and adapt based on life experiences. Both oxytocin and the experience of love can change over time. In spite of limitations, new knowledge of the properties of oxytocin has proven useful in explaining several enigmatic features of love.

Stress and love

Emotional bonds can form during periods of extreme duress, especially when the survival of one individual depends on the presence and support of another. There also is evidence that oxytocin is released in response to acutely stressful experiences, perhaps serving as hormonal “insurance” against overwhelming stress. Oxytocin may help to ensure that parents and others will engage with and care for infants; develop stable, loving relationships; and seek out and receive support from others in times of need.

Animal models and the biology of social bonds

To dissect the anatomy and chemistry of love, scientists needed a biological equivalent of the Rosetta Stone. Just as the actual stone helped linguists decipher an archaic language by comparison to a known one, animal models are helping biologists draw parallels between ancient physiology and contemporary behaviors. Studies of socially monogamous mammals that form long-lasting social bonds, such as prairie voles, have been especially helpful to an understanding the biology of human social behavior.

There is more to love than oxytocin

Research in prairie voles showed that, as in humans, oxytocin plays a major role in social interactions and parental behavior (Carter, 1998; Carter, Boone, Pournajafi-Nazarloo, & Bales, 2009; Kenkel et al., 2012). Of course, oxytocin does not act alone. Its release and actions depend on many other neurochemicals, including endogenous opioids and dopamine (Aragona & Wang, 2009). Particularly important to social bonding are the interactions of oxytocin with a related neuropeptide known as vasopressin . The systems regulated by oxytocin and vasopressin are sometimes redundant. Both peptides are implicated in behaviors that require social engagement by either males or females, such as huddling over an infant (Kenkel et al., 2012). For example, it was necessary in voles to block both oxytocin and vasopressin receptors to induce a significant reduction in social engagement, either among adults or between adults and infants. Blocking only one of these two receptors did not eliminate social approach or contact. However, antagonists for either the oxytocin or vasopressin receptor inhibited the selective sociality, which is essential for the expression of a social bond (Bales, Kim, Lewis-Reese, & Carter, 2004; Cho, DeVries, Williams, & Carter, 1999). If we accept selective social bonds, parenting, and mate protection as proxies for love in humans, research in animals supports the hypothesis that oxytocin and vasopressin interact to allow the dynamic behavioral states and behaviors necessary for love.

Oxytocin and vasopressin have shared functions, but they are not identical in their actions. The specific behavioral roles of oxytocin and vasopressin are especially difficult to untangle because they are components of an integrated neural network with many points of intersection. Moreover, the genes that regulate the production of oxytocin and vasopressin are located on the same chromosome, possibly allowing coordinated synthesis or release of these peptides. Both peptides can bind to and have antagonist or agonist effects on each other’s receptors. Furthermore, the pathways necessary for reciprocal social behavior are constantly adapting: These peptides and the systems that they regulate are always in flux. In spite of these difficulties, some of the different functions of oxytocin and vasopressin have been identified.

Functional differences between vasopressin and oxytocin

Vasopressin is associated with physical and emotional mobilization, and can help support vigilance and behaviors needed for guarding a partner or territory (Carter, 1998), as well as other forms of adaptive self-defense (Ferris, 2008). Vasopressin also may protect against physiologically “shutting down” in the face of danger. In many mammalian species, mothers exhibit agonistic behaviors in defense of their young, possibly through the interactive actions of vasopressin and oxytocin (Bosch & Neumann, 2012). Prior to mating, prairie voles are generally social, even toward strangers. However, within a day or so of mating, they begin to show high levels of aggression toward intruders (Carter, DeVries, & Getz, 1995), possibly serving to protect or guard a mate, family, or territory. This mating-induced aggression is especially obvious in males.

Oxytocin, in contrast, is associated with immobility without fear. This includes relaxed physiological states and postures that permit birth, lactation, and consensual sexual behavior. Although not essential for parenting, the increase of oxytocin associated with birth and lactation may make it easier for a woman to be less anxious around her newborn and to experience and express loving feelings for her child (Carter & Altemus, 1997). In highly social species such as prairie voles (Kenkel et al., 2013), and presumably in humans, the intricate molecular dances of oxytocin and vasopressin fine-tune the coexistence of caretaking and protective aggression.

Fatherhood also has a biological basis

The biology of fatherhood is less well-studied than motherhood is. However, male care of offspring also appears to rely on both oxytocin and vasopressin (Kenkel et al., 2012), probably acting in part through effects on the autonomic nervous system (Kenkel et al., 2013). Even sexually naïve male prairie voles show spontaneous parental behavior in the presence of an infant (Carter et al., 1995). However, the stimuli from infants or the nature of the social interactions that release oxytocin and vasopressin may differ between the sexes (Feldman, 2012).

At the heart of the benefits of love is a sense of safety

Parental care and support in a safe environment are particularly important for mental health in social mammals, including humans and prairie voles. Studies of rodents and of lactating women suggest that oxytocin has the important capacity to modulate the behavioral and autonomic distress that typically follows separation from a mother, child, or partner, reducing defensive behaviors and thereby supporting growth and health (Carter, 1998).

The absence of love in early life can be detrimental to mental and physical health

During early life in particular, trauma or neglect may produce behaviors and emotional states in humans that are socially pathological. Because the processes involved in creating social behaviors and social emotions are delicately balanced, these be may be triggered in inappropriate contexts, leading to aggression toward friends or family. Alternatively, bonds may be formed with prospective partners who fail to provide social support or protection.

Sex differences exist in the consequences of early life experiences

Males seem to be especially vulnerable to the negative effects of early experiences, possibly helping to explain the increased sensitivity of males to various developmental disorders. The implications of sex differences in the nervous system and in the response to stressful experiences for social behavior are only slowly becoming apparent (Carter et al., 2009). Both males and females produce vasopressin and oxytocin and are capable of responding to both hormones. However, in brain regions that are involved in defensive aggression, such as the extended amygdala and lateral septum, the production of vasopressin is androgen-dependent. Thus, in the face of a threat, males may be experiencing higher central levels of vasopressin.

Oxytocin and vasopressin pathways, including the peptides and their receptors, are regulated by coordinated genetic, hormonal, and epigenetic factors that influence the adaptive and behavioral functions of these peptides across the animal’s life span. As a result, the endocrine and behavioral consequences of a stress or challenge may be different for males and females (DeVries, DeVries, Taymans, & Carter, 1996). For example, when unpaired prairie voles were exposed to an intense but brief stressor, such as a few minutes of swimming, or injection of the adrenal hormone corticosterone, the males (but not females) quickly formed new pair bonds. These and other experiments suggest that males and females have different coping strategies, and possibly may experience both stressful experiences, and even love, in ways that are gender-specific.

In the context of nature and evolution, sex differences in the nervous system are important. However, sex differences in brain and behavior also may help to explain gender differences in the vulnerability to mental and physical disorders (Taylor, et al., 2000). Better understanding these differences will provide clues to the physiology of human mental health in both sexes.

Loving relationships in early life can have epigenetic consequences

Love is “epigenetic.” That is, positive experiences in early life can act upon and alter the expression of specific genes. These changes in gene expression may have behavioral consequences through simple biochemical changes, such as adding a methyl group to a particular site within the genome (Zhang & Meaney, 2010). It is possible that these changes in the genome may even be passed to the next generation.

Social behaviors, emotional attachment to others, and long-lasting reciprocal relationships also are both plastic and adaptive, and so is the biology upon which they are based. For example, infants of traumatized or highly stressed parents might be chronically exposed to vasopressin, either through their own increased production of the peptide, or through higher levels of vasopressin in maternal milk. Such increased exposure could sensitize the infant to defensive behaviors or create a lifelong tendency to overreact to threat. Based on research in rats, it seems that in response to adverse early experiences of chronic isolation, the genes for vasopressin receptors can become upregulated (Zhang et al., 2012), leading to an increased sensitivity to acute stressors or anxiety that may persist throughout life.

Epigenetic programming triggered by early life experiences is adaptive in allowing neuroendocrine systems to project and plan for future behavioral demands. But epigenetic changes that are long-lasting also can create atypical social or emotional behaviors (Zhang & Meaney, 2010) that may be especially likely to surface in later life, and in the face of social or emotional challenges.

Exposure to exogenous hormones in early life also may be epigenetic. For example, prairie voles treated postnatally with vasopressin (especially males) were later more aggressive, whereas those exposed to a vasopressin antagonist showed less aggression in adulthood. Conversely, in voles the exposure of infants to slightly increased levels of oxytocin during development increased the tendency to show a pair bond. However, these studies also showed that a single exposure to a higher level of oxytocin in early life could disrupt the later capacity to pair bond (Carter et al., 2009).

There is little doubt that either early social experiences or the effects of developmental exposure to these neuropeptides holds the potential to have long-lasting effects on behavior. Both parental care and exposure to oxytocin in early life can permanently modify hormonal systems, altering the capacity to form relationships and influence the expression of love across the life span. Our preliminary findings in voles further suggest that early life experiences affect the methylation of the oxytocin receptor gene and its expression (Connelly, Kenkel, Erickson, & Carter, 2011). Thus, we can plausibly argue that love is epigenetic.

The absence of social behavior or isolation also has consequences for the oxytocin system

Given the power of positive social experiences, it is not surprising that a lack of social relationships also may lead to alterations in behavior as well as changes in oxytocin and vasopressin pathways. We have found that social isolation reduced the expression of the gene for the oxytocin receptor, and at the same time increased the expression of genes for the vasopressin peptide. In female prairie voles, isolation also was accompanied by an increase in blood levels of oxytocin, possibly as a coping mechanism. However, over time, isolated prairie voles of both sexes showed increases in measures of depression, anxiety, and physiological arousal, and these changes were observed even when endogenous oxytocin was elevated. Thus, even the hormonal insurance provided by endogenous oxytocin in face of the chronic stress of isolation was not sufficient to dampen the consequences of living alone. Predictably, when isolated voles were given additional exogenous oxytocin, this treatment did restore many of these functions to normal (Grippo, Trahanas, Zimmerman, Porges, & Carter, 2009).

In modern societies, humans can survive, at least after childhood, with little or no human contact. Communication technology, social media, electronic parenting, and many other recent technological advances may reduce social behaviors, placing both children and adults at risk for social isolation and disorders of the autonomic nervous system, including deficits in their capacity for social engagement and love (Porges, 2011).

Social engagement actually helps us to cope with stress. The same hormones and areas of the brain that increase the capacity of the body to survive stress also enable us to better adapt to an ever-changing social and physical environment. Individuals with strong emotional support and relationships are more resilient in the face of stressors than those who feel isolated or lonely. Lesions in various bodily tissues, including the brain, heal more quickly in animals that are living socially versus in isolation (Karelina & DeVries, 2011). The protective effects of positive sociality seem to rely on the same cocktail of hormones that carries a biological message of “love” throughout the body.

Can love—or perhaps oxytocin—be a medicine?

Although research has only begun to examine the physiological effects of these peptides beyond social behavior, there is a wealth of new evidence showing that oxytocin can influence physiological responses to stress and injury. As only one example, the molecules associated with love have restorative properties, including the ability to literally heal a “broken heart.” Oxytocin receptors are expressed in the heart, and precursors for oxytocin appear to be critical for the development of the fetal heart (Danalache, Gutkowska, Slusarz, Berezowska, & Jankowski, 2010). Oxytocin exerts protective and restorative effects in part through its capacity to convert undifferentiated stem cells into cardiomyocytes. Oxytocin can facilitate adult neurogenesis and tissue repair, especially after a stressful experience. We now know that oxytocin has direct anti-inflammatory and antioxidant properties in in vitro models of atherosclerosis (Szeto et al., 2008). The heart seems to rely on oxytocin as part of a normal process of protection and self-healing.

Thus, oxytocin exposure early in life not only regulates our ability to love and form social bonds, it also affects our health and well-being. Oxytocin modulates the hypothalamic–pituitary adrenal (HPA) axis, especially in response to disruptions in homeostasis (Carter, 1998), and coordinates demands on the immune system and energy balance. Long-term, secure relationships provide emotional support and down-regulate reactivity of the HPA axis, whereas intense stressors, including birth, trigger activation of the HPA axis and sympathetic nervous system. The ability of oxytocin to regulate these systems probably explains the exceptional capacity of most women to cope with the challenges of childbirth and childrearing.

Dozens of ongoing clinical trials are currently attempting to examine the therapeutic potential of oxytocin in disorders ranging from autism to heart disease. Of course, as in hormonal studies in voles, the effects are likely to depend on the history of the individual and the context, and to be dose-dependent. As this research is emerging, a variety of individual differences and apparent discrepancies in the effects of exogenous oxytocin are being reported. Most of these studies do not include any information on the endogenous hormones, or on the oxytocin or vasopressin receptors, which are likely to affect the outcome of such treatments.

Research in this field is new and there is much left to understand. However, it is already clear that both love and oxytocin are powerful. Of course, with power comes responsibility. Although research into mechanisms through which love—or hormones such as oxytocin—may protect us against stress and disease is in its infancy, this knowledge will ultimately increase our understanding of the way that our emotions impact upon health and disease. The same molecules that allow us to give and receive love also link our need for others with health and well-being.

Acknowledgments

C. Sue Carter and Stephen W. Porges are both Professors of Psychiatry at the University of North Carolina, Chapel Hill, and also are Research Professors of Psychology at Northeastern University, Boston.

Discussions of “love and forgiveness” with members of the Fetzer Institute’s Advisory Committee on Natural Sciences led to this essay and are gratefully acknowledged here. We are especially appreciative of thoughtful editorial input from Dr. James Harris. Studies from the authors’ laboratories were sponsored by the National Institutes of Health. We also express our gratitude for this support and to our colleagues, whose input and hard work informed the ideas expressed in this article. A version of this paper was previously published in EMBO Reports in the series on “Sex and Society”; this paper is reproduced with the permission of the publishers of that journal.

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Cognition’s new ai tool devin is set to revolutionize coding industry, heated discussions erupt on reddit over chatgpt’s entry in scholarly publication, do you use quotation marks when paraphrasing, typely review, how to rewrite the sentence in active voice, the chemistry of love essay sample, example.

According to Dr. Helen Fisher , an anthropologist at Rutgers University, love as a holistic system can be divided into three basic subsystems , each with its own functional tasks and roles: sex drive, romantic love, and attachment. Sex drive is necessary to make a person start looking for partners; romantic love appears to help a person hold focus on one specific partner; attachment is crucial for building a long-lasting and reliable relationship with a selected partner (Chemistry.com).

Each of these subsystems need a driving force to operate and impact an individual’s behavior. Even though a loving relationship is a lot about psychology, it is still fueled by hormones; this is why using the expression “love chemistry” is fully justified. For the sex drive subsystem, testosterone and estrogen are crucial; the romantic love stage, or attraction, is “driven” mostly by dopamine and serotonin; attachment is sustained by such hormones as oxytocin and vasopressin (BBC Science).

Testosterone and estrogen are respectively male and female sex hormones that are responsible for sex-related physiological reactions, lust, and the motivation to look for a partner. Testosterone and estrogen cause sex drive to be present; however, specialists admit that sex can give a start to romance, as it increases the influx of dopamine to the brain (Chemistry.com). Dopamine and serotonin are hormones that cause euphoria and good mood; the same hormones are also secreted after taking certain drugs, so this is why one can be “high” from the feeling of love, act impulsively, and “get stuck” on the person they fell in love with. In its turn, attachment—as the most long-lasting phase of a love relationship—is driven by the same hormones that are responsible, in particular, for mother-and-child bonds (oxytocin); this hormone is also believed to be secreted when the two partners get intimate. So, a serious relationship is more about care and tenderness, than romance and turbulent feelings.

The popular expression “love chemistry” should be understood literally. Along with natural psychological processes, love is also, to a significant extent, dependent on the hormones secreted by our bodies during various stages of a relationship’s development. Sex drive, which makes us look for new partners (if we do not have one already), is regulated by the hormones of testosterone and estrogen. During moments of intimacy, the brain is affected by dopamine and serotonin—the hormones that are responsible for all the symptoms of romantic love, such as euphoria, concentration on the object of love, impulsiveness, and so on. As a relationship develops, it becomes reinforced by the hormones oxytocin and vasopressin; oxytocin, in particular, is the same hormone that is responsible for the forming of mother-and-child bonds. Thus, despite the claims that love is purely a solemn and sublime feeling, it also has a lot to do about biology and chemistry.

Dutton, Judy. “Love, Explained.” Chemistry.com. N.p., n.d. Web. 10 Feb. 2014. http://www.chemistry.com/datingadvice/LoveExplained.

“The Science of Love.” BBC News. BBC, n.d. Web. 10 Feb. 2014. <http://www.bbc.co.uk/science/hottopics/love/>.

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Exploring the chemistry behind love this Valentine's Day

by Bron Mills, University of Warwick

Chemistry in a relationship refers to the intense feelings of connection, passion, and romance that people share. This Valentine's Day, Dr. Alex Baker, a chemistry professor at the University of Warwick, explores the real chemistry behind chemistry. He explains how flowers and chocolates are as good as any love potion you could create to induce feelings of love.

According to Dr. Baker, four main chemicals are involved in love: dopamine , serotonin, adrenaline, and oxytocin.

• Dopamine provides you with feelings of pleasure and reward when you interact with your partner.
• Adrenaline gets the heart racing when you interact with your partner.
• Serotonin controls your mood, well-being, and even sexual desire and is mimicked in drugs like psilocybin in magic mushrooms. Low levels produce feelings of heartache.
• Oxytocin is responsible for feelings of trust and attachment and is released during sex.

Dr. Baker explains, "Interestingly, the structures of dopamine and adrenaline are very similar, only a few atoms of difference but a big difference in effect. Their chemistry is mimicked in medicines like amphetamine and salbutamol. The same reward centers in your brain are activated when you drink alcohol, so these are just different ways to reach the reward response."

"These chemicals aren't static, though; as the rollercoaster of love moves through the first meeting, the heartache, and into a long-term relationship, the presence of these chemicals changes the brain.

"For example, your serotonin levels recover, so you lose the anxiety and butterflies of love. How these chemicals fluctuate really impacts the emotions you feel—so I suppose is it love or just chemistry?"

So, based on the chemistry of love—it could be possible to produce a love potion. Dr. Baker explains, "One of the biggest issues from a biological perspective is how to get the chemicals, like dopamine, to the right place at the right time. This is a problem that stretches beyond hypothetical love potions to drug delivery to the brain.

"The other question to ask is, why not just buy chocolate and flowers instead of embarking on multimillion-pound love potion development? The phenethylamine in chocolate triggers dopamine release, while the flowers can trigger oxytocin release."

Provided by University of Warwick

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The Chemistry of Love

Reactions - Uncover the Chemistry in Everyday Life

Youtube ID: bp7Ydv5wAPk

Love has inspired timeless songs and sonnets — not to mention a few less-than-timeless romantic comedies. Now the chemistry of love is the subject of our latest  Reactions  episode! The video explains how feel-good neurotransmitters like dopamine and oxytocin fuel lifelong pair bonds in prairie voles, which — along with humans — are the mammalian kingdom's leading monogamists. "If you block oxytocin receptors, you can totally cut off that pair-bonding response," explains Abigail Marsh, Ph.D., associate professor of psychology at Georgetown University. "People who excite romantic feelings in us also probably trigger increases in oxytocin, which results in an increase in dopamine, and then we find that person someone we want to stick with." In the video, Marsh also explains that addictive drugs affect the brain in ways similar to love — which helps explain the painful, withdrawal-like symptoms of heartbreak.

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Essay on Love for Students and Children

500+ words essay on love.

Love is the most significant thing in human’s life. Each science and every single literature masterwork will tell you about it. Humans are also social animals. We lived for centuries with this way of life, we were depended on one another to tell us how our clothes fit us, how our body is whether healthy or emaciated. All these we get the honest opinions of those who love us, those who care for us and makes our happiness paramount.

What is Love?

Love is a set of emotions, behaviors, and beliefs with strong feelings of affection. So, for example, a person might say he or she loves his or her dog, loves freedom, or loves God. The concept of love may become an unimaginable thing and also it may happen to each person in a particular way.

Love has a variety of feelings, emotions, and attitude. For someone love is more than just being interested physically in another one, rather it is an emotional attachment. We can say love is more of a feeling that a person feels for another person. Therefore, the basic meaning of love is to feel more than liking towards someone.

Get the huge list of more than 500 Essay Topics and Ideas

Need of Love

We know that the desire to love and care for others is a hard-wired and deep-hearted because the fulfillment of this wish increases the happiness level. Expressing love for others benefits not just the recipient of affection, but also the person who delivers it. The need to be loved can be considered as one of our most basic and fundamental needs.

One of the forms that this need can take is contact comfort. It is the desire to be held and touched. So there are many experiments showing that babies who are not having contact comfort, especially during the first six months, grow up to be psychologically damaged.

Significance of Love

Love is as critical for the mind and body of a human being as oxygen. Therefore, the more connected you are, the healthier you will be physically as well as emotionally. It is also true that the less love you have, the level of depression will be more in your life. So, we can say that love is probably the best antidepressant.

It is also a fact that the most depressed people don’t love themselves and they do not feel loved by others. They also become self-focused and hence making themselves less attractive to others.

Society and Love

It is a scientific fact that society functions better when there is a certain sense of community. Compassion and love are the glue for society. Hence without it, there is no feeling of togetherness for further evolution and progress. Love , compassion, trust and caring we can say that these are the building blocks of relationships and society.

Relationship and Love

A relationship is comprised of many things such as friendship , sexual attraction , intellectual compatibility, and finally love. Love is the binding element that keeps a relationship strong and solid. But how do you know if you are in love in true sense? Here are some symptoms that the emotion you are feeling is healthy, life-enhancing love.

Love is the Greatest Wealth in Life

Love is the greatest wealth in life because we buy things we love for our happiness. For example, we build our dream house and purchase a favorite car to attract love. Being loved in a remote environment is a better experience than been hated even in the most advanced environment.

Love or Money

Love should be given more importance than money as love is always everlasting. Money is important to live, but having a true companion you can always trust should come before that. If you love each other, you will both work hard to help each other live an amazing life together.

Love has been a vital reason we do most things in our life. Before we could know ourselves, we got showered by it from our close relatives like mothers , fathers , siblings, etc. Thus love is a unique gift for shaping us and our life. Therefore, we can say that love is a basic need of life. It plays a vital role in our life, society, and relation. It gives us energy and motivation in a difficult time. Finally, we can say that it is greater than any other thing in life.

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Live Science

10 scientifically proven signs of love

Posted: February 18, 2024 | Last updated: February 20, 2024

How are the signs of love related to chemistry in the brain?

You may have experienced some signs you’re in love. Can't get someone out of your head? Daydreaming about them when you should be working? Imagining your futures together? These dizzying thoughts are just a few of the telltale signs of love.

In fact, scientists have pinned down exactly what it means to "fall in love." Researchers have found that the brain of a person in love looks very different from one experiencing mere lust, and it's also unlike the brain of someone in a long-term, committed relationship. Studies led by Helen Fisher, an anthropologist at Rutgers University and one of the leading experts on the biological basis of love, have revealed that the brain's "in love" phase is a unique and well-defined period of time. 

Here are telltale signs you're in love.

INTENSIFYING ATTRACTION

Going through some sort of adversity with another person tends to intensify romantic attraction, according to Fisher’s research. Central dopamine may be responsible for this reaction, too, because research shows that when a reward is delayed, dopamine-producing neurons in the mid-brain region become more productive.

INTRUSIVE THINKING

People who are in love report that they spend, on average, more than 85 percent of their waking hours musing over their "love object," according to Fisher. Intrusive thinking, as this form of obsessive behavior is called, may result from decreased levels of central serotonin in the brain, a condition that has been associated with obsessive behavior previously. (Obsessive-compulsive disorder is treated with serotonin-reuptake inhibitors.)

According to a 2012 study published in the Journal of Psychophysiology, men who are in love have lower serotonin levels than men who are not, while the opposite applies to women. The men and women who were in love were found to be thinking about their loved one for around 65 percent of the time they were awake.

EMOTIONAL DEPENDENCY

People in love regularly exhibit signs of emotional dependency on their relationship, including possessiveness, jealousy, fear of rejection, and separation anxiety. For instance, Fisher and her colleagues looked at the brains of individuals viewing photos of a rejected loved one, or someone they were still in love with after being rejected by that person. 

The functional magnetic resonance imaging (fMRI) showed activation in several brain areas, including forebrain areas like the cingulate gyrus that have been shown to play a role in cocaine cravings. "Activation of areas involved in cocaine addiction may help explain the obsessive behaviors associated with rejection in love," the researchers wrote in 2010 in the Journal of Neurophysiology.

PLANNING A FUTURE

Longing for emotional union with a beloved, seeking out ways to get closer and day-dreaming about a future together are also signs of someone in love. According to an article by Harvard University, when serotonin levels begin to return to normal levels, the hormone oxytocin increases in the body. This neurotransmitter is associated with creating more serious relationships.

Lucy Brown, a neuroscientist at the Albert Einstein College of Medicine in New York, says this drive to be with another person is sort of like our drive toward water and other things we need to survive.

"Functional MRI studies show that primitive neural systems underlying drive, reward recognition and euphoria are active in almost everyone when they look at the face of their beloved and think loving thoughts. This puts romantic love in the company of survival systems, like those that make us hungry or thirsty," Brown told Live Science. 

"I think of romantic love as part of the human reproductive strategy. It helps us form pair-bonds, which help us survive. We were built to experience the magic of love and to be driven toward another"

FEELINGS OF EMPATHY

People who are in love generally feel a powerful sense of empathy toward their beloved, feeling the other person's pain as their own and being willing to sacrifice anything for the other person.

In Fisher’s study, the scientists discovered significant patterns in the brain activity of people who were in love. Their mirror neurons, which are linked to feelings of empathy, were more active in people who were in a long-term, loving relationship. 

ALIGNING INTERESTS

Falling in love can result in someone reordering their daily priorities to align with those of their beloved. While some people may attempt to be more like a loved one, another of Fisher's studies, presented in 2013 at the "Being Human" conference, found that people are attracted to their opposites, at least their "brain-chemical" opposites. 

For instance, her research found that people with so-called testosterone-dominant personalities (highly analytical, competitive and emotionally contained) were often drawn to mates with personalities linked to high estrogen and oxytocin levels — these individuals tended to be "empathetic, nurturing, trusting and prosocial, and introspective, seeking meaning and identity," Fisher said in 2013.

POSSESSIVE FEELINGS

Those who are deeply in love often experience sexual desire for their beloved, but there are strong emotional strings attached: The longing for sex is coupled with a desire for sexual exclusivity, and extreme jealousy when the partner is suspected of infidelity. According to the Indian Journal of Endocrinology and Metabolism, oxytocin is released during sexual activity. This hormone, as mentioned above, creates social bonds and develops trust.

This attachment is thought to have evolved so that an in-love person will compel his or her partner to spurn other suitors, thereby ensuring that the couple's courtship is not interrupted until conception has occurred. According to Fisher this evolved as a biological need, enabling people in romantic relationships to “focus [their] mating energy on a particular individual”. 

CRAVING AN EMOTIONAL UNION

While the desire for sexual union is important to people in love, the craving for emotional union takes precedence. Fisher’s 2002 study published in Archives of Sexual Behavior found that 64 percent of people in love (the same percentage for both sexes) disagreed with the statement, "Sex is the most important part of my relationship with [my partner]."

FEELING OUT OF CONTROL

Fisher and her colleagues found that individuals who report being "in love" commonly say their passion is involuntary and uncontrollable.

For her 1979 book "Love and Limerence," the late psychologist Dorothy Tennov asked 400 men and women in Connecticut to respond to 200 statements on romantic love. Many participants expressed feelings of helplessness, saying their obsession was irrational and involuntary. 

According to Fisher, one participant, a business executive in his early 50s wrote this about an office crush, "I am advancing toward the thesis that this attraction for Emily is a kind of biological, instinct-like action that is not under voluntary or logical control. ... It directs me. I try desperately to argue with it, to limit its influence, to channel it (into sex, for example), to deny it, to enjoy it, and, yes, dammit, to make her respond! Even though I know that Emily and I have absolutely no chance of making a life together, the thought of her is an obsession," Fisher reported in 2016 online in Nautilus.

LOSING THE SPARK

Unfortunately, being in love doesn't always last forever and psychologists say that the early euphoric stage lasts no longer than three years, according to Fisher’s blog. It's an impermanent state that either evolves into a long-term relationship that psychologists call "attachment," or it dissipates, and the relationship dissolves. If there are physical or social barriers inhibiting partners from seeing one another regularly — for example, if the relationship is long-distance — then the "in love" phase generally lasts longer than it would otherwise.

To find out why people crave love and learn more about the research of Helen Fisher, you can watch her TED talk–  The brain in love . For further reading about love and the body, the book  The Science of Love and Attraction , written by neuroscientist Dr. Guloglu, explores how and why people love. 

"Romantic love: An fMRI study of a neural mechanism for mate choice" The Journal of Comparative Neurology (2005).  https://onlinelibrary.wiley.com/doi/abs/10.1002/cne.20772

"Differences in Neural Response to Romantic Stimuli in Monogamous and Non-Monogamous Men". Archives of Sexual Behaviour (2017).  https://link.springer.com/article/10.1007/s10508-017-1071-9

"The benefits of positive illusions: Idealization and the construction of satisfaction in close relationships". Journal of Personality and Social Psychology (1996).  https://psycnet.apa.org/record/1996-01707-007

"Reduced cognitive control in passionate lovers". Leiden, Universiteit (2013).  https://www.sciencedaily.com/releases/2013/11/131111091355.htm

"Addicted to love: What is love addiction and when should it be treated?". Philosophy, Psychiatry and Psychology (2017).  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5378292/

"Reward, Addiction, and Emotion Regulation Systems Associated With Rejection in Love".  Journal of Neurophysiology (2010).  https://journals.physiology.org/doi/full/10.1152/jn.00784.2009

"Defining the brain systems of lust, romantic attraction, and attachment. Archives of Sexual Behavior (2002).  https://www.researchgate.net/publication/11151468

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Guest Essay

How ‘Past Lives’ Changed My Mind About My Relationship

By Euny Hong

Ms. Hong is a cultural critic.

My most stressful moviegoing experience last year was not the mushroom cloud in “Oppenheimer” or the murder trial scenes in “Anatomy of a Fall,” but watching the story of a love triangle among a Korean American woman, a Korean guy and a white guy in the Oscar-nominated “Past Lives.” In the film, Nora, our 30-something heroine, and Arthur, her white husband, are living happily in New York when Nora is contacted by Hae Sung, her childhood sweetheart in South Korea, with whom she had reconnected online as a young adult.

He tells her he’s planning to visit the city. When he arrives, it’s clear he still has feelings for her. Given this situation, I knew at least one person would be very upset by the end of the movie. For most of the film, I felt that person was going to be me.

On the one hand, as a Korean woman, I really wanted Nora to pick the Korean guy. As Arthur says to Nora, “If this was a story someone was telling, I’d be the evil white American husband keeping you two apart!” Every Asian American woman is aware of a longstanding Hollywood trope: The white male savior who sweeps in to save an “exotic” Asian woman, a scenario that goes back at least as far as Anna May Wong’s roles in the 1920s.

The maddening corollary to the white savior trope is that the Asian guy never gets the girl. I still recall the incredulity my friends and I felt coming out of a theater in 1998 having just watched “The Replacement Killers,” a movie in which the dreamy Chow Yun-fat saves the gorgeous Mira Sorvino, yet it doesn’t even occur to them to hook up.

On the other hand, I was having these thoughts while watching “Past Lives” in a movie theater sitting next to my boyfriend, who is white.

As an Asian woman living in the West, I learned long ago that every dating choice I make becomes a referendum: on race, on feminism — you know, just some of the most explosive issues of our day. If you happen to be dating a white guy, well, your relationship feels as if it’s being policed by loved ones and strangers alike. Some of them will accuse you of being psychologically damaged or of plotting to extinguish your people. You may even internalize some of these beliefs.

Before I was old enough to know how babies were made, I was taught by my whole extended family that marrying a white guy would damn my descendants and that an Asian couple was the correct, harmonious order of things. (It also made for a tidier Christmas card photo, or so I was told.)

The first time I watched “Past Lives,” I had this kind of policing in mind. I was fixated on Hollywood’s historical depictions of Asian women and recalling how the very first time I ever saw two Asian characters kissing in a Hollywood film wasn’t until 2018, with “Crazy Rich Asians.” (I think I audibly gasped.)

Of course I hoped for Nora to get together with Hae Sung: I could view the love triangle story line only through a lens that presumed that one outcome was necessarily good while the other was necessarily bad. I dutifully rooted for the good one, although it contradicted my real-life experience, as personified by the man sitting in the theater next to me.

But when I rewatched the film, which is up for best picture on Sunday, I realized it’s a smarter movie than that and truer to life as well. The broad premise of “Past Lives” may be “who will she choose?” but the reason it’s an affecting experience is not that it’s concerned with abolishing tropes or righting representational wrongs. Instead, it’s a story about three good people, trying to do right by one another, fumbling and faltering but finding their way through.

For Nora, the only fitting choice in the end is her husband, Arthur, not because he is (or isn’t) white but because he is the right choice for her. To run off with Hae Sung — whether he’s Asian or not — would not have made any sense, given what we learn about her character and relationship. Reflexively rooting for that to happen made no sense for me, either.

I have my own “Past Lives” moment, sort of. I first met my boyfriend in 1996 at a party thrown by mutual friends from college. We went on one horrible date — I take responsibility; being dense, I didn’t realize it was a date and kept whining about some clown who had just dumped me — and both decided we wanted nothing more to do with each other. Unexpectedly, 26 years later, in late 2022, I had to interview him in my role as a journalist. Reacquainted, we hit it off.

Why did things click this time and not previously? As Heraclitus wrote, you can’t step in the same river twice. To me, that’s the real lesson of “Past Lives”: We have to move forward, not back. As Nora ends up saying to Hae Sung, referring to her Korean name, Na Young, and her new home, New York: “The Na Young you remember doesn’t exist here.” When she chooses to stay with Arthur, she explains it by saying, “This is where I ended up.”

It might sound like a blowoff, but, in the film, it’s a deep and moving declaration of commitment. It’s also a moment that felt deeply authentic to me. The first time I watched the film, I worried that someone’s feelings would be crushed, maybe mine. But when I left the theater with my boyfriend, I didn’t feel heartbroken at all.

Euny Hong is a cultural critic.

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Processing of Biogenic Material for Energy and Chemistry

Biomass Conversion and Biorefinery - Call For Papers - Developments in biomass conversion and biorefinery – Status 2024

Biomass Conversion and Biorefinery is proud to present an upcoming thematic issue, entitled:

Developments in biomass conversion and biorefinery – Status 2024

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The prime objective of this Thematic Issue is to gather research papers from different challenging areas within the field of biomass conversion and biorefinery including environmental, physical, chemical, and biological aspects dealing with the latest advances and trends in research. Outstanding research papers on biomass and/or biowaste energy tackling the following fields are expected:

• Green energy and the environment 
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• Combinations between biomass and biowaste used as a raw material and as an energy carrier 

The focus of this thematic issue is on original research papers with novel findings and new results meetings the highest scientific standards in the research field outlined above. Research papers falling within the scope of this Call and presented at the 1 st International Conference on Advances in Environmental Sustainability, Energy and Earth Science (AESEE-2023) are welcome. Please review the whole Call for Paper (this opens in a new tab) for more details.

Targeted opening and closing date for manuscript submission to the thematic issue:

Opening Date  : March 1 st , 2024 Closing Date   : November 30 th , 2024

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Dr. Pankaj Pathak Associate Professor in the Department of Environmental Science & Engineering at SRM University, AP, India. Her area of domain includes solid and hazardous waste management, waste to energy and circular economy, and has a keen interest in sustainable green energy resources.

Dr. Javid Ahmad Dar Assistant Professor at the Department of Environmental Science & Engineering at SRM University, AP, India. He is a forest ecologist, working on tropical forest biomass & carbon dynamics, ecosystem modeling, biodiversity and other ecological parameters in response to climate change.

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Journal of Materials Chemistry A

Carbon-based double-metal-site catalysts: advances in synthesis and energy applications.

Dual-metal site catalysts embedded in a carbon matrix (referred to as DMSCs) are gaining significant interest in sustainable energy research. Their distinct coordination settings, electronic configurations, efficient atom usage, and enhanced catalytic performance position them at the cutting edge of this field. The purpose of this article is to summarise the latest key findings of carbon-based diatomic catalysts for synthetic methods and energy applications. Firstly, the classification of carbon-based diatomic catalysts into two categories (homonuclear (A2) and heteronuclear (AB)) is presented, and their synthesis strategies are described. Following this, we provide a synopsis of the latest developments in carbon-based dual-metal catalysts for applications related to energy, encompassing processes such as hydrogen production, oxygen generation, oxygen consumption, carbon dioxide conversion, and nitrogen fixation. To sum up, future prospects, potential challenges, and opportunities for the advancement of carbon-supported bimetallic catalysts are explored.

• This article is part of the themed collections: Journal of Materials Chemistry A Recent Review Articles and Journal of Materials Chemistry A HOT Papers

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L. Wang, Z. Wei, Z. Sun, L. Zhu, Y. Gao, W. Chen, S. Li and Z. Chen, J. Mater. Chem. A , 2024, Accepted Manuscript , DOI: 10.1039/D4TA00727A

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