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Relationships and Brain Evolution

How Relationships Influence Brain Development

The Social, Emotionally Intelligent Brain

The last two decades have produced more research on the brain and more new brain technologies than all the discoveries of the past. This new information not only changes how we view the brain, but also reveals that our mental capacity remains a lifelong work-in-progress.

Learn how your brain develops—from infancy through adulthood—and how that development affects your relationships throughout life.

Social make-up of the brain

Over the last two decades, researchers have produced a greater amount of information about the brain, and scientists have developed more new brain technologies, than in all previous studies of human cognizance. This huge outpouring of information has greatly expanded our knowledge of the human brain—providing data on brain development and explaining the brain’s links to interpersonal communication and relationships. This study of the brain:

  • increases our understanding of personal and interpersonal mental health problems
  • highlights the critical importance of early nonverbal love relationships
  • explains why many of us find it so difficult to build and maintain productive, exciting, and meaningful relationships at home and at work
  • assures us that change is always possible
  • suggests ways that we can change

Relationships and our nervous systems

Through the new brain scanning technologies, science has also revealed that not only is the brain capable, at birth, of building new neural pathways based on experience, but that it retains that ability throughout life. We used to believe that the brain was incapable of change once we were adults—now we don’t! According to UCLA child psychiatrist and developmental specialist, Daniel J. Siegel, “At birth, the brain is the most undifferentiated organ in the body—with a plasticity that enables it to create new circuitry throughout life.”

This capacity for structural and functional change is most apparent in infancy and early childhood—but it never really ceases. In fact, modern ways of measuring the brain’s electrical activities and new types of brain scans confirm this ability for life-long learning. Scientists using brain imagery technologies to study people over age ninety have found that their subjects’ brains continue producing new neural pathways even though older pathways are dying. We now understand that the brain remains capable of renewing itself throughout life—so, our minds are always a work in progress.

The Human Brain is a Work-in-Progress

  • the brain is always capable of changing
  • the brain is especially open to change through relationship
  • experience can override genetic predisposition
  • new experience can create circuitry that overrides past experience

This means that even after many decades of failed communication in home and work relationships, we can make changes that bring us the safety, mutual connection, and excitement we need and deserve.

Influences of infant–caregiver relationships 

Research data that help us understand how relationships shape the brain include the fact that, at birth, the human brain is not fully formed. It has few neural pathways at this stage, because these are formed through the baby’s experiences. The brain continues its development at a rapid pace in a child’s first three to five years of life—as a result of the quality of relationship between the infant and his or her primary caretaker. This first interactive relationship, known as the attachment bond, plays a critical developmental role. This relationship, determined by the quality of communication between infant and caregiver, predicts the success or failure of the child’s future relationships.

The introduction of brain imaging resources—including electroencephalogram (EEG), quantitative EEG studies (QEEG), positron emission tomography (PET), single photon emission computed tomography (SPECT) and functional MRI (fMRI)—helps us to see and understand how experience affects the flow and function of information within the brain. The experience that has the most influence on the developing brain is that which is acquired in intimate relationships. Video-based studies of infants and their caregivers conducted in thousands of homes around the world have illustrated the influence of the attachment bond on the nervous system. Such research has led to the conclusion that the attachment bond relationship plays a dominant role in the development of the brain, the individual, and his or her connection to others and the world. The security (or insecurity) of a child’s early attachment relationship establishes the basis for:

  • lifelong relationships with others
  • a sense of security about exploring the world
  • resilience to stress
  • the ability to balance emotions and make sense of the inner and outer world

Relationships change the way our brains function

Human relationships—our interactions with other people—shape the brain’s neural pathways, including those that are genetically programmed. Numerous recent studies on the brain and development show us that the brain responds to:

  • only one primary person at birth
  • nonverbal messages throughout life
  • emotional cues throughout life

In The Developing Mind, Daniel J. Siegel uses the phrase “the feeling of being felt” to describe relationships that shape the mental circuits responsible for memory, emotion, and self-awareness. Brain-altering communication is triggered by deeply felt emotions that register in facial expressions, eye contact, touch, posture, movements, pace and timing, intensity, and tone of voice.

The brain’s remarkable adaptability at birth, together with the infant’s emotional focus on its primary caregiver, sets up a lifelong pattern for the individual’s thoughts, feelings, and behavior. This evolving pattern continues to affect the individual’s relationships, helping them to succeed, allowing them to fail, or assisting in healing damaged relationships. And, because the brain remains flexible throughout life, it remains capable of continually changing. Such changes are brought about through nonverbal communication with people with whom we are emotionally attached. Researcher Allen N. Schore also draws this conclusion when he describes “self-organization” as a “dyadic process” or two-person communication, based on play and emotional understanding. Today, dozens of researchers all over the world attribute this “dyadic process” to a wordless form of communication that links infant and caregiver in “a dance of mutual joy and discovery.” As we grow older, we continue this dependence on one another for changing the way our brains function.

Resolved conflict may stimulate brain development

Challenges that don’t lead to overwhelming stress may stimulate the growth of new brain cells. Stem cells are found in the amygdala, the repository for emotional impressions and memories in the brain, suggesting a relationship between emotional challenges and the development of new cells throughout life. Since overwhelming emotional stress has the reverse effect on the growth of brain cells, the potential for growth may be linked to conflict resolution. Noted researcher Allen N. Schore, in his groundbreaking, Affect Regulation and the Origin of the Self, cites studies that show more increased brain development occurring in young children during periods of conflict at ages two to three. The interface between conflict, brain cell growth and development and conflict resolution may be provided by greater understanding of the attachment bond.

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External Resources

How much do we really know about the brain? – An interview with four prominent psychologists and neuroscientists about our knowledge of the brain and its development, including the translation of research into advice for parents or educators. (Frontline: PBS)

Without Miracles: Brain Evolution and Development – Explanation of brain evolution and “rewiring” including learning and memory processes. (University of Illinois)

Interview with Daniel Siegel, MD – A discussion of Dr. Siegel’s book, "The Developing Mind - Toward a Neurobiology of Interpersonal Experience." (

Authors: Jeanne Segal, Ph.D., and Jaelline Jaffe, Ph.D. Last updated: May 2013.

© All rights reserved. This reprint is for information only and NOT a substitute for professional diagnosis and treatment. is an ad-free non-profit resource for supporting better mental health and lifestyle choices for adults and children.