Category Archives: the biology of love

How Our Brain Can Love for Years

Posted on by

People have a very basic need for love, which affects both their bodies and minds. We need to love someone and be loved by someone. People from different cultures and situations may experience and show love in different ways. However, their basic human need for love is still the same everywhere (Karandashev, 2019).

Love is a feeling and an expression of emotion that arises from the activation of specific neurological and physiological processes in the human body and brain. Throughout biological evolution, our mammalian ancestors have developed these biological mechanisms for the capacity and necessity of love (Karandashev, 2022).

In other articles, I talked about how our brain evolves its ability to love and how the human brain works when we fall in love.

Brain in Love

In the last two decades, researchers have conducted numerous studies on the neurophysiological processes that underpin our feelings of love. Brain imaging techniques have proven to be a valuable tool for studying human cerebral functions related to love and romance.

Neuroimaging studies have revealed what occurs in their brains and bodies in the early stages of romantic love when we are falling in love. As a couple progresses from the initial euphoria of affection to a state of deeper commitment, the activation regions of the brain undergo expansion.

How the Brain Works After Partners Marry

Researchers discovered that when newly married couples viewed images of their long-term partner, certain regions of the brain’s basal ganglia were activated.

As Lucy Brown, a neuroscientist from Einstein College of Medicine in New York, commented,

“This is an area of the brain heavily involved in promoting attachment, giving humans and other mammals the ability to stick it out even when things aren’t going quite so well.”

People may show the patterns of brain activation corresponding to romantic love for many years after marriage. For example, long-term married partners who have been together for 20 years or more exhibited neural activity in regions of the brain that are rich in dopamine and associated with reward and motivation. This finding aligns with previous studies on the early stages of romantic love.

In the study of neural correlates of long-term intense romantic love, participants exhibited greater neural activity in the ventral tegmental area (VTA) when they perceived the pictures of their long-term spouse compared to the images of a close friend or a highly familiar acquaintance. The study also revealed common neural activity in several regions that are frequently activated during maternal attachment, such as the frontal, limbic, and basal ganglia.

As Stephanie Cacioppo, a professor from the University of Chicago, and her colleagues found, long-term love also increases activation in more cognitive areas of the brain. Among those are the angular gyrus, which is associated with complex language functions, and the mirror neuron system, which helps us anticipate the actions of a loved one.

According to Cacioppo, this is the rationale behind the evidence that partners seamlessly navigate a tiny kitchen while cooking together or can finish each other’s sentences.

“People in love have this symbiotic, synergistic connection thanks to the mirror neuron system, and that’s why we often say some couples are better together than the sum of their parts. Love makes us sharper and more creative thinkers,”

Stephanie Cacioppo commented

What Occurs in Our Brain When We Fall in Love with Someone?

Posted on by

The need for love is one of the most basic physiological and psychological needs people have. We need to love someone and be loved by somebody. Although people’s experiences and expressions of love may vary across cultures and situations, their basic human needs for love are still universal across the world (Karandashev, 2019).

I wrote about how our brain developed the ability to love in another article.

The activation of certain neural and physiological mechanisms in our body and brain generates the psychological experience and expression of love. These biological mechanisms for the capacity and necessity to love have developed in our mammalian ancestors throughout the course of biological evolution (Karandashev, 2022).

How Our Brain Works When We Fall in Love

Studies of the neurophysiological processes involved in our feelings of love have proliferated in the last two decades. Brain imaging techniques have been a valuable method to study human cerebral functions associated with love and romantic relationships.

Neuroscientists have traditionally investigated the subcortical structures of reward-related systems involved in the experience of love. Later neuroimaging studies showed that, in addition to these subcortical structures, different cortical networks and cognitive factors play an important role in reward-related systems associated with the experience of love.

Several scientists investigated how men and women feel in the early stages of romantic love and what occurs in their brains and bodies. Early-stage romantic love often induces euphoria.

What is happening in our brains when we are falling in love? According to Lucy Brown, a neuroscientist at Einstein College of Medicine in New York, and her colleagues, the first activation of love occurs in a primitive part of the brain’s reward system that is located in the midbrain. This finding once again confirms that our ability to love stems from the long evolutionary history of our animals’ ancestors. It is possible that romantic love originated from a mammalian drive to pursue preferred mates.

Functional Magnetic Resonance Imaging of Love

Lucy Brown and her colleagues studied seven men and ten women who were “in love” using the method of functional magnetic resonance imaging (fMRI). Some of these participants were intensely in love, while others were moderately in love or had a low thrill for their partner.

Participants in this study alternately perceived a photograph of their beloved and a photograph of another familiar person that researchers exposed to them in the fMRI machine. When participants perceived the photo of their romantic partner, they experienced a feeling of love. What occurred in their brain? Researchers recorded brain activation in the midbrain’s ventral tegmental area (VTA). This is the part of the brain connected to meeting basic needs, such as eating when we are hungry and drinking when we are thirsty.

Professor Brown commented,

“It’s the area of the brain that controls things like swallowing and other basic reflexes. While we often think about romantic love as this euphoric, amorphous thing and as a complex emotion, the activation we see in this very basic part of the brain is telling us that romantic love is actually a drive to fulfill a basic need.”

The Hormones of Love

Stephanie Cacioppo, a professor from the University of Chicago, and her colleagues revealed more findings on how love affects our brains.

Researchers found 12 areas of the brain that are activated to release chemicals such as dopamine, the hormone associated with “feel-good,” oxytocin, the hormone associated with “cuddle hormone,” and adrenaline, which stimulates a euphoric sense of purpose. These findings also showed that the brain’s reward circuit, which includes the amygdala, the hippocampus, and the prefrontal cortex, is sensitive to behaviors that induce pleasure. These parts of the brain are active when we are talking about a loved one, and these areas have increased blood flow.

When these processes are occurring in the brain, our level of serotonin, a hormone responsible for the regulation of appetite and intrusive anxious thinking, decreases. Low levels of serotonin are common among men and women experiencing anxiety and obsessive-compulsive symptoms.

“This explains why people in the early stages of love can become obsessed with small details, spending hours debating about a text to or from their beloved,”

Stephanie Cacioppo

How Our Brain Developed the Ability to Love

Posted on by

Love is one of our core psychological and biological needs. We need to love, and we need to be loved. These needs are cross-culturally universal, even though the way people experience and express their love may differ across societies and contexts (Karandashev, 2019).

As a cross-cultural psychological phenomenon, love stems from some basic neural and physiological processes that occur in our brain and body. The need and capability to love evolved over a long history of biological evolution (Karandashev, 2022).

The Neurophysiological Evolution of Love

The evolution of the mammalian autonomic nervous system (ANS) has provided a neurophysiological basis for emotional processes related to the experience and expression of love, such as reproduction, proximity, and safety (Porges, 1998). Sexual arousal, passionate sexual activities, and long-term pair bonding develop as a result of phylogenetic changes in the autonomic nervous system (ANS). The vagus nerve of the mammalian autonomic nervous system (ANS) is anatomically connected to the cranial nerves that control social interaction between individuals through vocalization and facial expression. Subsequently, courting, love, and seduction behaviors develop.

Mammal Neural Systems for Love

Mammal brain systems exhibit specific neural activity patterns related to sexual behavior, affectionate emotions, and love. Several brain systems are involved in mating, including neural systems for sensory perception and cognitive and emotional responses to the object of love.

Dopaminergic reward pathways are the specific brain mechanisms involved in sexual and romantic attraction (Dixson, 1998, 2009; Fisher, Aron, & Brown, 2006; Panksepp, 1998).

Passionate attraction during courtship in mammalian species is directly associated with increased levels of central dopamine and norepinephrine, as well as decreased levels of central serotonin in the brain’s reward pathways (Fisher, 2004; Herbert, 1996).

Mammalian Human Brain

Functional magnetic resonance imaging (fMRI) in humans has revealed that passionate attraction and love are associated with activity in primitive brain regions (Aron et al., 2005; Bartels & Zeki, 2000, 2004; Fisher, Aron, & Brown, 2006; Ortigue et al., 2010, see for review, Karandashev, 2022). Passionate love involves the brain’s subcortical reward pathway and motivation systems focusing on a specific person. Thus, basic evolutionary mechanisms embed the basic emotion of love. This form of love could have appeared early in hominid evolution, providing people with emotional signals for mate selection (Fisher, 2004).

A Distinctive Smell Influences Our Emotions and Love

Posted on by

Smell is the most mysterious of the five senses, with an evocative power that can transfer us to different times, places, emotional states, and even the state of love. The scent of a particular perfume has a distinctive smell that may remind us of a loved one. The aroma of baking bread may bring us back to childhood. A whiff of hospital disinfectant may cause us to feel uneasy. However, the impact of scent on human behavior extends beyond these evocative moments.

This article, as well as others on this blog, will review the intricate relationships between human scent—a distinctive smell—and our feelings, emotions, perceptions, and behaviors.

The Science of Smell: Knowing the Power of a Distinctive Smell

Understanding the science of smell (olfaction) is essential when we explore the role of smell in our perceptions, emotions, and behaviors. The olfactory organs and neurons in the nose interact with molecules in the air when we take a deep breath through the nose. The brain receives data from these neurons and uses it to determine what we are smelling.

The special feature of this sensory processing is that the limbic system of the brain, which controls emotion, memory, and behavior, is directly connected to the olfactory neurons. Because of this direct path, smells can have powerful and immediate effects on our feelings, perceptions, emotions, and behavior.

The “Proustian Phenomenon” of the Effect of Distinctive Smell on Memory

Marcel Proust (1871–1922), the famous French novelist, portrayed a character who vividly recalled long-forgotten childhood memories after consuming a madeleine cake dipped in tea. This ‘Proustian phenomenon’ illustrates how aromas can evoke powerful and vivid memories.

The olfactory bulb, which processes smell, has strong connections to the amygdala and hippocampus, which control emotion and memory, respectively. This unique relationship explains why a specific scent can immediately evoke intense emotional memories.

A Direct Connection Between Smell and Emotion

Scent may have a significant impact on our emotional state in addition to how we remember the past. A certain smell can elicit a variety of emotions, ranging from contentment and relaxation to disgust and anxiety. For example, lavender, which has a calming effect, is frequently used in aromatherapy to ease stress and promote sleep. On the other hand, the smell of spoiled food or rotten eggs may cause disgust and a strong desire to leave the area.

The Subtle Yet Significant Effect of Smell on Social Connections

Smell is a big part of how people connect with each other. Animals use scents called pheromones to signal to one another. The scientific idea of ‘chemical communication’ through these scents is well investigated in various species. Pheromones determine the smells that animals give off to communicate with each other.

Researchers are still investigating the effects of human pheromones on their emotions and behaviors. Some studies show that smells do play a role in how people get attracted to each other and form relationships. Men and women are more likely to hang out with others who have a scent they like.

The Power of Scent Is Subtle in Its Effect on Us

The influence of smell on human emotions, perceptions, and behaviors is profound and intricate. It is still not fully comprehended, yet it is clear that our sense of smell is intricately connected to our emotions, memories, and behaviors. We can anticipate uncovering more fascinating insights into the subtle yet potent role of scent in our life and love.

Other posts on this blog show the role of various sensory experiences, including smell, on human preferences in romantic relationships. Some studies, for example, revealed the most attractive smells for love. Other studies explored the tactile and kinesthetic senses of love.

The Biological Evolution of Human Bonding and Love

Posted on by

The basic human need for positive social connections that have evolutionary and social roots is the foundation of love relationships. These origins can be traced all the way back to the beginning of recorded history. (Karandashev, 2022, chapter 3).

The evolutionary need for bonding and love derived from the early evolutionary distinction between “ingroup” and “outgroup.” The “ingroup” is us, and the “outgroup” is them.

The need to belong to an “ingroup” became the core of human motivation. Belonging to an “ingroup” provided security, subsistence, and psychological attachment to others whom they needed for survival.

The Evolutionary Need to Belong

People clearly benefit from living in cooperative and supportive groups that work together and help each other. People who live with others are safer and have a greater sense of physical, social, and psychological survival security. They had more consistent access to food and a greater capacity to defend themselves from raiders due to cooperation. Therefore, those ancestors of humans who lived in tribal communities had a greater chance of surviving.

People are “social animals” that have survived because they worked together, helped, and supported each other, their family, and their tribe. While hunting, they discovered that more hands are always better than two. As food gatherers, they gained protection from threats by traveling in groups. Those with a stronger sense of community were more likely to live longer. They had more and better offspring, which made them the dominant genetic group.

“Love as a means of community bonding” is the main thing that brings people together and makes their relationships stronger. As social beings, they have a better chance of staying alive when they live together because they can help each other. This is why the need to belong is intrinsic to human nature. Subsequently, men and women have an innate need to belong.

Social Bonding That Enables Human Physical Survival

When people belong to a social group, they have a greater chance of surviving because the group can provide better access to resources for maintaining sustenance and security. Those who live in tribal communities have a greater sense of security in their social connections than those who live alone. When members of a community work together to share resources, it makes it easier for them all to obtain food, water, and shelter. In addition to this, they are better able to defend themselves against predators as well as aggressive outsiders attacking them.

Social Bonding That Empowers Psychological Survival

In a later stage of evolution, human motivation also included the need for psychological security in addition to physical security. In tribal subsistence-based and traditional collectivistic societies, extended family, kin, and the tribal community provided sufficient conditions for secure social bonding. The ties of tribal community and kinship were the social relations that kept people together in many small-scale, low-technology societies of the past.

Over the course of evolution, the need to belong to a group and feel safe psychologically and emotionally became the driving force behind all human behavior. Strengthening one’s physical and psychological strength, as well as developing supportive relationships, became vital to surviving in life.

Thus, bonding, the need to belong, and the need for love all have their roots in our evolutionary past, which I discussed at length elsewhere (Karandashev, 2022, chapter 3).

How People Were Domesticated

Natural selection almost certainly played a role in the development of social abilities, social bonding, and prosocial behavior during the course of human evolutionary history. “Domestication syndrome” was at work with humans in the same way as with animals.

Brian Hare, a Professor of Evolutionary Anthropology at Duke University, proposed the theory that explains the “Survival of the Friendliest” (Hare, 2017). According to this theory, humans domesticated themselves in the latter stages of evolution. In the course of evolution, human social skills emerged and evolved when natural selection began to favor in-group pro-sociality over aggression.

Social characteristics in humans evolved as a result of a “domestication syndrome” similar to that seen in other domesticated animals. The meta-analysis of many studies from the fields of paleoanthropology, neurobiology, and developmental biology was in accord with this evolutionary theory of domestication (Hare, 2017).

Evolution of Animal Bonding and Love

Posted on by

Many people love birds, cats, dogs, and other animals. They enjoy being around them and feel a pull to help them when they can. Do animals love us back?

Indeed, animals do feel emotions such as joy, love, fear, despair, grief, and others. It is also true that many animals are capable of loving the people who care for them. And they love us, not just because we feed them; they love us as companions.

The needs for positive connections and bonding with others are evolutionary motivations that have evolved over time in social animals and humans. These origins can be traced all the way back to the natural evolution of other social species, such as dogs, cats, and primates (Karandashev, 2022, chapter 3).

Love as Social Bonding Among Animals

Researchers documented substantial evidence that certain animals and humans, during the course of their evolution, have developed the psychological mechanisms of cooperation, prosocial behavior, and social bonding. These evolved mechanisms aided their survival in both nature and society (e.g., Germonpré, Lázniková-Galetová, Sablin, & Bocherens, 2018; Marshall-Pescini, Virányi, & Range, 2015; Hare, 2017; 2006; Fisher, 2004; Rosenblum & Plimpton, 1981; see Karandashev, 2022, Ch. 3 for a review). 

According to the findings of neuroscience, a wide variety of animals have the physiological mechanisms that enable them to experience love as feelings of strong affection for another animal or person.

Evolution of Oxytocin

Oxytocin is the hormone of love and social bonding. Along with the evolution of animal and human social behavior and the capacity for social connections, oxytocin has accordingly evolved. This chemical messenger’s roles in the brain are associated with a positive social relationship, attachment, caring, and interpersonal trust (Carter, 1998, 2014; Carter, Williams, Witt, & Insel, 1992; De Boer, Van Buel, & Ter Horst, 2012, see for review Karandashev, 2022, Ch. 3).

Varieties of Relationship Systems in Animals

Various interindividual relationships may exist among social species that live in groups. Many of these relationship systems engage multiple females and multiple males. And the relationships are promiscuous. Others are usually pair-bonded species that live in groups with only one female and one male (Lukas & Clutton-Brock 2013; Reichard & Boesch 2003; see for review Karandashev, 2022, Ch. 3).

Love as Social Bonding Among Dogs

Dogs have a well-earned reputation for being social and friendly with people. Dogs may have descended from wolves. Yet their social behavior has diverged from that of their wild ancestors. Some archeological findings and scholarly speculation point to the possibility that in prehistoric times certain wolf subspecies began to settle in close proximity to human settlements. (e.g., Germonpré et al., 2018; Marshall-Pescini et al., 2015; Morell, 1997; see for review Karandashev, 2022, Ch. 3).

Instead of competing for prey, they started to prefer helping the people who fed them in exchange for their service. Those friendly wolves had a better chance of survival and reproduction. Natural evolutionary selection was favorable to those wolf-dog hybrids for their cooperative tendencies toward humans. The domestication process took place, and those variants of wolves eventually evolved into domestic dogs. Nature chooses those who are best suited to the conditions under which they must survive.

Love as Social Bonding Among Primates

Like other social species, the chimpanzee groups have a variety of different behavioral traits and interindividual relationships. Nevertheless, they all share the characteristics that define them as a distinct “chimpanzee society.” They might also pursue distinct mating strategies and have different mating systems (Chapais, 2011).

Bonding as a basic form of love seems to be present among some primates. Infant primates are hardwired to cling to their mothers, and even a brief separation causes anxiety. They start looking for their mothers. They are overjoyed and excited to be back. It appears that infant primates certainly experience love as attachment (Rosenblum & Plimpton, 1981).

It appears clear that a desire for union and a desire to avoid separation are the fundamental motivations that give them a better chance of survival. Unlike those of other primates, human societies are the only ones where multiple reproductive pairs remain together (de Waal & Gavrilets 2013).

Love Is a Social Connection, even between Zebrafish

Posted on by

Social connections and pair-bonding between conspecifics are widespread forms of love among humans, primates, mammals, dogs, and birds. What about fish? Here we’ll talk about the simple form of how zebrafish love their conspecifics.

Is Love Simply a Connection?

Some scholars consider love as a positive social connection, as a way of social bonding between individuals. It is perfectly true. I believe that many forms of human love evolve from a basic need to positively connect, bond, and belong. Human life depends on having a positive connection with other people. People need other people, whether they are close or far from us, to live and do well (see for review, Karandashev, 2022a, in press).

Love Is Social Bonding

According to evolutionary and cultural theories, community bonding was the earliest form of love. This type of love stemmed from basic survival needs in the ecological, economic, and social conditions under which people lived in specific environments and societies. The varieties of historically evolved cultures determined specific forms of love.

It’s well known that humans are “social animals.” It is possible, however, that many animals are also “social.” Studies show that not only humans, but also other animals have evolved the psychological mechanisms of prosocial behavior, cooperation, and social bonding that have helped them survive in the natural and social worlds (e.g., Germonpré, Lázničková-Galetová, Sablin, & Bocherens, 2018; Marshall-Pescini, Virányi, & Range, 2015; Hare, 2017; 2006; Fisher, 2004; Rosenblum & Plimpton, 1981, see for review Karandashev, 2022a in press).

Humans are not alone in their propensity to cooperate with members of their own species to meet their needs and to survive and thrive. For example, in nature, herds of mammals, flocks of birds, or shoals of fish abundantly exhibit prosocial tendencies. There is plenty of evidence of social bonding in dogs and primates (see for review, Karandashev, 2022a, in press).

Throughout thousands of years of biological evolution, special physiological and neural mechanisms of social connection and love have evolved in animals and humans (e.g., Buss, 2006; Eastwick, 2009; Esch & Stefano, 2005; Fisher, Aron, & Brown, 2006; Fletcher et al., 2015; Gonzaga & Haselton, 2008; Lampert, 1997; Zeki, 2007, see for review Karandashev, 2022a, in press).

Social connections necessitate that an individual recognize others as belonging to their own sort. How does the brain of an animal recognize other members of its own species?

Connections and Attractions of Zebrafish

Johannes Kappel, Johannes Larsch, and their colleagues at the Max Planck Institute for Biological Intelligence investigated this process in juvenile zebrafish. They found a neural circuit that mediates the social attraction of zebrafish. This path, which goes from the retina to the brain, lets zebrafish detect and approach neighboring conspecifics.

Recent studies by scientists at the Max Planck Institute for Biological Intelligence have discovered the neural processes in young zebrafish that enable zebrafish to detect and approach nearby conspecifics. Researchers found that zebrafish social attraction is mediated by a neuronal circuit—the specialized pathway that runs from the retina all the way into the brain.

Shoaling Behavior of Zebrafish

Scientists investigated the role of the visual system and neuronal processing of the stimulus in the social interactions of zebrafish. Experiments demonstrated that a moving dot activates a particular collection of neurons in the thalamus region of the brain. The thalamus is the brain’s sensory control center, integrating and relaying sensory information.

When another zebrafish larva is nearby, the same region of the thalamus becomes active. On its way to the thalamus, sensory information is processed first in the retina and then in the tectum, a key visual center of the vertebrate brain. When information gets to the thalamus, it has already been checked for social cues, like jerky movements from a possible conspecific.

The Brain Regions for Social Behavior Are Connected with the Visual System of Zebrafish

These nerve cells connect the visual system of the zebrafish to other brain regions that are active during social behavior. Researchers thus discovered the visual triggers of this brain activation.

When researchers were able to inhibit newly found neurons, zebrafish larvae lost interest in both conspecifics and moving dots and no longer followed them around. Thus, it was proven that these neurons regulate social approach and affiliation in zebrafish.

These findings increased our understanding of the brain region whose activation provides the basic “glue” for the connection of two zebrafish. These small-scale interactions collectively form shoals of fish. And all this social behavior is governed by neural networks of this kind.

What about human social behavior?

Humans also have a thalamus, and their numerous neural processes have been conserved throughout evolution. The role of these regions in people’s social behavior has yet to be investigated.

Researchers Found More Hormones of Love

Posted on by

Romantic love has an adaptive function in human evolution. It increases reproductive success in sexual relations between men and women through the hormone of love. The evolution of animal and human bonding results in the evolution of love hormones.

When men and women are in passionate love, many psychophysiological and neuropsychological processes occur in their brains and bodies. They affect how their minds and behaviors function. In recent decades, researchers have revealed the important role that hormones plays in passionate love. They conducted studies on neuroimaging, biochemistry, and hormones (Hatfield & Rapson, 2009; Gangestad & Grebe, 2017; Sorokowski et al., 2019).

Hormones Play a Role in Romantic Love

These changes are especially pronounced when they are falling in love. Being close to a beloved partner elicits strong romantic feelings and produces corresponding hormonal changes. The hormones cortisol, testosterone, oxytocin, prolactin, and estradiol engage in emotional and behavioral reactions associated with love feelings.

For example, men and women who are in romantic love have higher cortisol. The excited state of passionate arousal they experience when they fall in love causes the increased cortisol level. Other hormonal changes also facilitate pair bonding and commitment.

Some discoveries about the effects of various hormones on romantic love are consistent and well-known. Other findings are sometimes contradictory and need further research. A recent study indicated one more hormonal secret of love that is worthy of our attention (Sorokowski et al., 2019).

Does Love Increase a Woman’s Fertility?

Researchers from the University of Wrocław, Poland, conducted the study to show that love produces adaptive hormonal changes in the female body. These changes increase a woman’s fertility when she is in love (Sorokowski et al., 2019).

In their study, researchers measured the levels of several hormones in women in the early follicular phase of the menstrual cycle. They compared the blood serum levels of estradiol, cortisol, free testosterone, prolactin, luteinizing hormone, and follicle-stimulating hormone of those women who were at the beginning of passionate romantic relationships with those who were not in love.

Hormones of Love Involved in Experience of Emotion

Researchers reported that women in love have higher levels of gonadotropins and lower free testosterone levels compared to those who are not in love. At the same time, women in love have the same levels of cortisol, prolactin, and estradiol. Researchers also revealed that the estradiol-to-testosterone ratio is higher in women in love in comparison with women who are not in love. Researchers suggest possible explanations for these results based on their associations with other confounding factors they identified in their study. They admit that some of the results aren’t completely convincing and that more research needs to be done.

Here Is One More Hormone of Love

Nevertheless, this study seems about to crack one more hormonal secret of romantic love. It turned out that the experience of falling in love plays an adaptive function. It increases the likelihood that the romantic couple will conceive offspring in their sexual relations. This discovery explains why men and women across the world tend to experience not only sexual attraction but also love. Heterosexual love is an important adaptive psychological mechanism that increases women’s physiological ability to conceive a child.

What Is Imprinting?

Posted on by

Generally, imprinting (linguistically, it is a derivative of “printing”) means marking or impressing a sign or mark on the surface of anything.

Imprinting in Ethology

In ethology, the science of animal behavior, imprinting stands for a sensitive period, usually very early in the life of an animal, when instant or fast learning occurs. It is a time in which newborn animals form attachments to members of their own species. Imprinting has been used to domesticate animals and birds for generations.

A typical example of imprinting is when ducklings follow their mother duck, which they see moving within a few hours after they hatch. Young ducks tend to imprint and follow their mother duck. They also imprint the first individual of their species that they interact with during this ‘sensitive’ period of biological development. The same way they would imprint on and follow any first large object they see moving. This is how their love for and attachment to “mother” is forming. They become attracted to the movement, sound, and smell of the first-appearing object in their life.

The science of imprinting can explain “Who is your mama?”

What are the functions of imprinting in love attraction and love attachment? How can imprinting affect our kinship, mating relationships, and love?

Does Imprinting Form an Infant’s Attachment and Love Bonds of Kinship?

Imprinting seems to allow animals to instinctively recognize other animals of their own species, thus developing a model of their species’ “identity.” This identity naturally drives their attraction to their “mother”, “kin”, and others of the same kind. We can view this attraction as an animal’s early prototype of infants’ love bonds with their species’ kin.

Konrad Lorenz, an Austrian naturalist, ornithologist, and ethologist, discovered and first investigated the phenomenon of “imprinting” in the early 1900s (see for review, Bateson, 1978; Hess, 1958; Lorenz, 1935; Tzschentke & Plagemann, 2006).

Lorenz revealed that when young birds—little ducks or geese—came out of their eggs, they became attached to the first moving object they encountered. It is typically their mother. Natural selection prepared the hatchlings to form an instant and strong bond with their mother. We can consider this effect as an early form of “attachment love”—the loving attachment of an infant to a mother.

However, when Lorenz placed himself as the object of their attraction (instead of their mother), the young birds attached to him as a mother substitute. Working with ducks and geese, Lorenz showed evidence that such attraction and attachment happen during sensitive periods in their lives. Once such attraction and attachment were ‘fixed,’ they persisted for a long time. Geese responded to Lorenz as a parent and followed him about everywhere. When they became adult birds, they preferred to court him over other geese.

The same way, they would easily attach to any inanimate object, such as a white ball, a pair of gumboots, or even an electric train. The most crucial aspect of such attachment is that these objects appear at the appropriate time.

Does Imprinting Affect an Animal’s Sexual Love for Its Own Species?

Those early imprinting studies revealed that early imprinting forms not only family love bonds but also sexual preferences in mating. This can explain why animals do not mate with any other animals except those of their own species. From an evolutionary perspective, genetic similarity is vital for sexual attraction and mating in birds and mammals. Such mating preferences help select the proper mate. They cannot reproduce offspring with anyone. They can only do this with those with whom they have a higher chance of mating success than with others (Lampert 1997).

Birds and mammals cannot mate with animals of other species. They are genetically too distant to produce offspring. This mechanism explains the genetic secrets of attraction and love.

Let us consider the example of sexual imprinting among birds. Early works by Konrad Lorenz demonstrated that the early experiences that birds and animals have in their lives could significantly affect not only their “kinship” bonds. Such an early imprinting experience could also form their mating preferences and their love for each other. Lorenz suggested that sexual imprinting gives adults a predilection to recognize their own species (Lorenz, 1935).

Lorenz found that geese responded to him not only as parents, following him everywhere, but later in their lives, when they became adult birds, they preferred to court him rather than other geese.

Thus, sexual imprinting of attraction and the shaping of love happen in the early periods of birds’ and animals’ lives.

Here Are More Complex Effects of the Imprinting

Experimental studies of the mid-20th century supported early findings on imprinting. The early experiences of animals can certainly have long-lasting impacts. Nonetheless, those later studies indicated that birds may show their preferences for members of their own species even if they don’t have experience with any of them except themselves (Immelmann, 1969; Schutz, 1965).

This means that birds may have a predisposition for their own species without prior experience. But the early years’ sexual imprinting merely refines this predisposition under natural conditions.

Another explanation suggests that sexual imprinting plays a role in the recognition of close kin. This way, the selection of mates that are slightly different allows the animal to reach an optimal balance between inbreeding and outbreeding. Birds have the strongest mating preference for

“something a little different (but not too different) from the object with which it had been imprinted.”

(Bateson, 1978, p. 659).

The studies found that a bird does indeed mate with a slightly unfamiliar female. The bird prefers this unfamiliar female to the one that appeared in the early life of the bird. Nevertheless, the bird prefers both types of these females to those with a markedly unfamiliar type of plumage (Bateson, 1978).

These findings show the power of genetic similarity and genetic diversity in attraction and attachment.

You Fall in Love with Someone Genetically Similar to You

Posted on by

This article explains the surprising findings of studies which show that you are more likely to fall in love with someone who has genetic similarities to you.

The Irresistible Attraction of Genetic Similarity

What is more attractive to a loving person: similarities or differences? What draws people to each other? Do they like those who resemble themselves, or do opposites attract? It is commonly known that “birds of a feather flock together.” Multiple studies have also provided evidence to support this similarity effect (see for review, Karandashev, 2019).

Studies have demonstrated that men and women tend to initiate relationships with those who resemble them in such characteristics as socio-economic status, income, ethnicity, religion, cultural identity, age, and even body type (Karandashev, 2022).

Generally, when it comes to race, ethnicity, or even size and shape, people tend to fall in love with those like themselves. Spouses tend to have a higher level of genetic similarity than two random strangers.

Are We Genetically Predisposed to Fall in Love?

The quality of our relationship is influenced by more than just our shared experiences with a partner. In evolutionary terms, establishing interconnectedness necessitates the display of similarities between organisms. In humans, we tend to select our mating partners according to the principle of optimal genetic similarity. Because sexually dimorphic animals like humans cannot produce healthy offspring with anyone, intersexual attraction aids them in the proper selection of a mate. It’s possible that biological evolution has created a psychological mechanism that unconsciously attracts us to mates who are similar to us while excluding those who are significantly different (Lampert 1997).

We tend to fall in love with others who are genetically similar to us and look alike. We are drawn to each other subliminally because of our genetic resemblance (Robinson et al., 2017).

On the other hand, this evolutionary mechanism of optimal genetic similarity prevents incest in human societies and other species, reinforcing incest taboos (Lampert 1997).

Genetic Studies of Marital Similarity

Genetic similarities with the partner appear to be important for their short-term sexual attraction and long-term loving relationships. For example, the thousands of cases of DNA paternity tests provided evidence that men and women, when they were in sexual relations, were genetically more similar to each other than random couples (Rushton, 1988).

These findings suggest that partners are likely to recognize their genetic similarity. They experience sexual attraction without even realizing it.

Another genetic study using genome-wide SNPs in a sample of married couples in the US is also in support of this similarity explanation (Domingue et al., 2014).

Researchers discovered that spouses have significantly more genetic similarities than any two randomly chosen individuals. Surely, compared to siblings, who have around 40–60% genetic similarity, marital partners share considerably less genetic similarity. Thus, spouses tend to share a greater degree of genetic similarity than other members of the population. The contribution of a genetic factor is statistically significant. Yet it is a relatively modest one.

How Our Genes Make Us Fall in Love

The GG genotype is the set of specific genes within the oxytocin gene receptor that affects our feelings of love. The studies of the GG genotype show how genetics affect a person’s feelings toward another and a relationship between partners. Our genes determine what hormones we are predisposed to and, therefore, what personal traits we exhibit in relationships. When our hormone levels are out of balance, we may have difficulties in our ability to create interpersonal relationships and bonds. For instance, low levels of testosterone and estrogen can cause low sexual drive. Consequently, this may cause low relationship satisfaction.

Several studies have demonstrated that individuals who have the GG genotype have greater sociability, empathy, and emotional stability. It has been shown that these psychological resources are associated with happier close relationships (see for review, Monin et al., 2019).

The quality of our marriage is influenced by more than just our shared experiences. A recent study of the GG genotype, which included 178 American couples, discovered its genetic impact on marital relationships (Monin et al., 2019). Researchers revealed that when at least one person in a couple has the GG genotype, he or she is less anxious in psychological attachment to the partner, and both partners benefit by feeling significantly higher marital satisfaction than other couples with different genotypes. Even though the percentage of this genetic impact on marital satisfaction is small (about 4%), it is statistically significant compared to other factors.

How Environmental, Social, and Cultural Factors Make Us Fall in Love

Environmental, social, and cultural factors also play a substantial role in explaining why we fall in love (see more elsewhere). Similarities in social class, political orientation, ethnicity, religion, education, interests, and characters of partners play substantial roles, which are frequently more important than genetic similarities.

Other Articles of Interest on This Topic