Why Love Matters: How Affection Shapes a Baby’s Brain

An explanation for why loving relationships are essential to brain development in the early years.

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Karsen: From the Parents Club, I’m Karsen Kolnicki. This is your briefing.


Karsen: Today, we’re discussing Why Love Matters. Written by Sue Gerhardt.

In this title, the author explains her interpretations of the latest findings of why love is essential to brain development in the early years of life, particularly to the development of our social and emotional brain systems, and presents the startling discoveries that provide the answers to how our emotional lives work.

Karsen: Vincent Phamvan on the key takeaways [pause] and what you need to know.


Karsen: Vincent, in the age-old question of nature versus nurture, does the author have an opinion on this?

Vincent: Gerhardt immersed herself in psychoanalysis, neuroscience, and biochemistry to find the answer to this question. By exploring the research, she found that the answer is neither. We’re neither hardwired at birth nor are we assembled over many years.

Instead, who we are is inscribed into our brains in the first two years of our lives.

Karsen: Oh, that’s really interesting. So both sides are right.

Vincent: She says that babies have highly “plastic” brains, which means that the way that we’re treated as infants creates neurological patterns that stick with us for the rest of our lives. So love and care create one type of person, while anxiety and neglect create another type of person.

So anyway, it’s not nature versus nurture. It’s both. She argues that it’s both that shape who we are today.

Karsen: As the brain develops, what are the different stages of development?

Vincent: As the brain develops, there are three different stages of development. We have what neuroscientists call a triune brain, or three brains in one. And each of these three brains reflects a different stage in our evolution.

In the first stage, we develop a brain similar to that found in reptiles. It’s a simple cognitive setup that’s based around the brainstem and supports basic life functions like breathing.

The next stage is a mammalian brain which develops around the reptilian core. This allows for basic emotions, which in turn add new qualifies like the ability to nurture offspring.

Karsen: And the third stage?

Vincent: In the third stage, which is the final stage, we develop the cerebral cortex in the outer layers of the brain. This is where the social brain is formed. The social brain is what makes humans different from other animals.

It controls our emotions, allows us to follow social cues, and experiences empathy. Instead of merely experiencing primal emotions like fear, anger, or satisfaction, we can feel deeper and more complex states like sadness, shame, guilt, love, pleasure, happiness, and more.

While most mammals see the world in black and white, our social brain allows us to see it in color.

Karsen: So when a baby is born, their social brain isn’t fully developed yet?

Vincent: Right, the author says that the social brain is missing when a baby is born, and it only begins developing after a baby is born.

That’s why sometimes a baby just won’t stop crying or just won’t eat the vegetables you’ve been trying to feed them.

Karsen: Because a baby doesn’t understand that mom or dad is frustrated… and eating the carrots would make dad really happy.

Vincent: The author explains that’s because the social brain, which is responsible for complex emotions, only develops after a baby is born.

Karsen: So what can parents do to help the social brain develop?

Vincent: That’s a great question. The baby’s brain development is determined by the quality of social interaction they experience.

Before a baby can control his or her behavior, a key part of their social brain needs to develop. This part of the brain is called the orbitofrontal cortex and it’s responsible for emotional intelligence.

Without this part of the brain, social life can be pretty badly impaired. The experiences that babies have in the first few years of their lives mold the orbitofrontal cortex. This is what researchers call experience dependency… where that part of the brain is built up through experience.

Karsen: So that means that babies can adapt and learn whatever culture they’re born into.

Vincent: Yes, exactly. They can quickly pick up the rules and norms within any culture. It’s easy to build up a baby’s brain. But it also means that it’s just as easy to damage it.

There was a famous experiment in the 1930s by primate researcher Harry Harlow, where he found that if you isolate a monkey for the first year of its life, it will become autistic. So sociability really depends on social interaction.

Another study in Romania looked at the brains of three-year-olds born in the country’s orphanages. Many of these children spent years neglected with little contact with adults. When the researchers reviewed brain scans, they found large, empty spaces where the orbitofrontal cortices should be. So social deprivation in the first few years of life can cause permanent damage.

Karsen: What are some ways parents can stimulate social interactions for their babies?

Vincent: One of the first ways that parents and caregivers can make social interactions pleasurable for their children is through touch. Babies love to touch and look at their carers.

Being lovingly held in dad’s arms, where it’s warm and safe, has an immediate physiological effect on a baby. As he or she relaxes, their breathing deepens, and their heart rate and nervous system will actually synchronize with their dad’s.

Karsen: How else do babies experience pleasure from social interactions?

Vincent: Another source of deep pleasure comes from looking. When a baby gazes into their mother’s eyes, they can “read” her dilated pupils. This can tell him or her that her nervous system is experiencing pleasurable arousal, which triggers the arousal of their own nervous system. It sets off a biochemical chain reaction.

When the baby’s heart rate rises, neurons release opioid-like molecules called beta-endorphins into the orbitofrontal regions of the baby’s brain.

Karsen: and what does that do?

Vincent: Well, that does two things. First, it triggers a sense of pleasurable arousal, and second, it regulates glucose and insulin levels, which stimulates neuron growth. All of this will release dopamine into the prefrontal cortex, further promoting tissue growth in the prefrontal brain.

Karsen: All of this sounds really complex, but in simple terms, having social interactions with babies can come down to touch and eye contact. The more a baby does this, the more the social brain grows.

Vincent: That’s right. A baby is born with all the neurons that they’ll ever have. This is determined by genes. However, their brain will double in size over the first year of their life. The neurons need to be connected, and this is the work that takes place outside of the womb. So it’s the social factors that determine the final shape and health of the brain.

Karsen: Is there a peak time for cognitive construction of the baby’s brain?

Vincent: Gerdhart says that cognitive development peaks between the age of six and twelve months. At the end of this period, a dense network of cognitive possibilities emerges. The process is not completely done yet.

Later on, the next process is called pruning. This is where rarely-used brain cells begin dying off. So the brain keeps connections that are useful and gets rid of those that are not useful.

Daniel Siegel explains that the brain is an “anticipating machine” and its purpose is to help people navigate the world. So when it notices patterns or things happening, again and again, it marks those things as important.

Experiences that aren’t likely to happen again don’t get remembered, since they’re not very useful as predictors. Since this information has little predictive value, the brain assumes it can be safely discarded.

Karsen: How can other factors, like stress, have an impact on adults and babies?

Vincent: The author explains that human stress is an evolutionary reflex that goes back to our prehistoric ancestors, who lived in a world filled with life-threatening dangers.

When we’re faced with danger, like running into a bear or a tiger, the brain releases a hormone called cortisol. It sounds an alarm to tell other bodily systems to stop whatever they’re doing to deal with the emergency.

Karsen: It’s a good thing that we’re not faced with those types of dangers daily in modern society.

Vincent: Modern society is a lot safer, but our survival still depends on social acceptance and social status. So when these are threatened, the author says that these old stress response still kicks in.

Karsen: What happens if cortisol levels stay high for too long?

Vincent: That’s a great question. If the body’s cortisol levels don’t return to normal, this can damage the immune system and make it less effective. That’s why people who are stressed out get sick more often.

Adults can manage stress levels by booking massages or meeting with friends. If things get really bad, they can talk to a therapist or change jobs.

Karsen: Babies can’t do any of those things though.

Vincent: Babies definitely can’t change jobs. So if parents don’t manage cortisol levels effectively, they risk exposing their babies to large amounts of stress, which can have long-term impacts.

Karsen: What are stressful situations for babies?

Vincent: Well, babies rely on their caregivers for survival, so one of them is the absence of their caregiver, which can be really distressing.

Babies can’t survive without caregivers. They can’t feed themselves, protect themselves, or keep themselves warm. The only thing they can do is cry. So when their pleas for attention and help go unanswered, babies experience a profound sense of powerlessness.

A 2002 study showed that mammals that are separated from their mothers at a young age have higher cortisol levels. Each time a squirrel monkey was separated from his mother, his cortisol levels increased. When this happened repeatedly, even for just five hours a week, the monkey’s feedback sensitivity increased. Over time, he became clingy, more easily distressed, and less playful.

Karsen: Does the research show the same can happen with humans?

Vincent: Possibly. The other research suggests that high cortisol levels during the early years can have a similar long-term effect in humans. Early exposure to cortisol was linked with a reduced number of cortisol receptors later in life. Because these receptors absorb cortisol, they help manage the overall levels of his hormone. So with fewer receptors, it’s harder to manage stress.

Karsen: So neglected babies who weren’t held had fewer cortisol receptors, and babies who had been touched and held a lot had a much higher number of receptors. And that translates to increased stress management later on in life.

Vincent: Yes, that’s what the research indicates.

Another interesting piece of research mentioned by the author points to the fact that stressed parents have stressed children.

Karsen: Can you share more about that study?

Vincent: Sure, There was a 2002 study from psychologist Marilyn Essex, where she followed 570 families for five years between the birth of their children and their fifth birthdays. She regularly tested the stress levels of the children and parents.

When Essex measured the stress levels of children at age four and a half, she found that those who were currently living with stressed mothers had high cortisol levels, but only if their mothers had also been stressed when their children were infants. So the children were only vulnerable if they had difficult babyhoods.

Children as they progressed through childhood experience the legacy of the early tensions. So if they had more difficult babyhood, then they’ll find it harder to cope with difficulties later in life.

Karsen: Wow, that’s fascinating. So it sounds like a brain with plenty of cortisol receptors can mop up stress hormones. And the best way to develop those is at a young age.

Vincent: That’s right. Social deprivation during babyhood is linked to depression later in life. A brain that hasn’t enjoyed a peaceful and protected babyhood is likely to develop an overactive stress response system. When a baby experiences stress, his or her brain will be flooded with cortisol and his or her cortisol receptors will shut down.

When they have fewer receptors, the cortisol released during times of stress have nowhere to go, so they stay in the brain, which causes depression in the long term.

Social deprivation during babyhood is also linked with a permanent reduction in dopamine synapses. Children with a lot of dopamine flowing will often feel positive about new experiences and quickly learn to adapt to specific challenges. However, a lack of dopamine synapses causes a child to be less likely to focus on positive rewards, less able to adapt, and more prone to depression and giving up.

Karsen: It sounds like the key takeaway from this book is that that love matters. The more loved and protected that we feel as babies, the more likely we are to develop into healthy adults. Humans are social creatures. Social skills like empathy don’t exist at birth. They develop after we’re born by building up social interactions. That’s why the quality of our early interactions is important to shaping our fully functioning social braining. But if a baby is exposed to lots of stress, they’ll be more likely to suffer from depression and less likely to cope in later life.


Karsen: That’s it for your briefing. I’m Karsen Kolnicki. See you next time.


Why Love Matters explains why loving relationships are essential to brain development in the early years and how these early interactions can have lasting consequences for future emotional and physical health.

This second edition follows on from the success of the first, updating the scientific research, covering recent findings in genetics and the mind/body connection, and including a new chapter highlighting our growing understanding of the part also played by pregnancy in shaping a baby’s future emotional and physical well-being.  

The author focuses in particular on the wide-ranging effects of early stress on a baby or toddler’s developing nervous system. When things go wrong with relationships in early life, the dependent child has to adapt; what we now know is that his or her brain adapts too. The brain’s emotions and immune systems are particularly affected by early stress and can become less effective. This makes the child more vulnerable to a range of later difficulties such as depression, anti-social behavior and addictions or anorexia, as well as physical illness.

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