One’s life has value so long as one attributes value to the life of others.
—Simone de Beauvoir
MOST SCIENTISTS STUDY INDIVIDUALS AND THEIR organs in isolation from one another rather than in the context of entire bodies, families, and communities. This bias has led us to think of the brain as an isolated organ and to search for technical solutions for human dilemas. Because this way of thinking has shaped our view of the natural world, it is easy to forget that we are part of a living system that we depend on to survive—from neurons to neighborhoods to nations. From conception to death, we impact and are impacted by the biology and behavior of those around us. In essence, we human beings are social animals who use our brains to connect us to one another.
Compared to other animals, humans are born with extremely immature brains and an immense number of uncommitted neurons. It is precisely this latent potential that allows our brains to be maximally influenced by the particular environment into which we are born. Thus, each of our brains is customized to fit into our unique social niche within the concentric habitats of family and community.
The layers of the fossil record of life on earth reveal the progression from single-celled organisms to increasingly complex forms of life. Over time, single-celled organisms joined together to form an amazing diversity of structures that enhanced the survival of larger organisms and groups of separate organisms. We see the progression from simple sea creatures that floated freely or attached to rocks to those that directed their own movements to search for food and mates. Eventually, sea creatures evolved into species that would come to live on land and in the air, expanding to fill the earth.
In the same way that different forms of life emerge to adapt to new environments, each species continues to evolve to better adapt to changes in the environment. In humans, natural selection favored increasing brain size as a way of expanding behavioral flexibility and eventually the development of culture. As primates evolved increasingly large brains, more brain development needed to occur after birth so that the newborn’s head wouldn’t be too large to pass through the birth canal and for the mother to survive giving birth. To provide for the prolonged postnatal development of less mature offspring, primates dedicated increasing amounts of energy to taking care of their young. Groups of primates also had to develop more sophisticated means of communication and cooperation while becoming smarter about how they invested their time in hunting and gathering. Getting smarter included division of labor, strategizing, and cooperation. See Table 1.1 for a summary of those adaptations.
Table 1.1. The Interwoven Evolution of Brain and Social Structure
| More Complex Brains Allow: | More Complex Social Structure Allows: |
| Greater adaptation | Increased role differentiation |
| Response flexibility | More sophisticated caretaking |
| Better problem solving | Longer periods of childhood dependency |
| Role specialization | Transmission of learning |
| Sophistication of attachment | The emergence of culture |
In an endless cycle of reciprocal feedback and adaptation, more sophisticated brains facilitated more complex social structures, communication, and caretaking. In turn, these skills allowed for even larger brains, opening the door for the emergence of new skills and abilities.
Because our brains have evolved as social organs, they are built and regulated in the context of relationships. You know that warm feeling you get when you see an adorable baby, the reflexive wince when you see a loved one in pain, or that palpable magnetism of being drawn to someone you find attractive? These feelings, triggered by chemical processes within dedicated social neural networks, have evolved to promote bonding, attachment and cooperation, mutual care, and altruism. These everyday human experiences connect our bodies, hearts, and minds into the superorganisms we call families, tribes, and nations.
THE FABRIC OF LIFE
Our individual lives cannot, generally, be works of art unless the social order is also.
Charles Horton Cooley
Why do humans have such complex social relationships? Is all the gossip, drama, and social ritual really necessary? Mother Nature certainly loves to combine simple structures to create more complex forms of life.1 Bacteria, ants, and gazelles have all evolved as interdependent systems. The behaviors of colonies, armies, and herds provide a level of adaptation beyond that of individuals. Penguins stand together in large groups during cold weather—the ones on the outer edge burrow toward the center for warmth while those toward the center, who are warmer, relax and drift to the colder periphery. In this way, a group of a certain size can survive as a whole in an environment where a smaller group or an individual could not.
If we assume that the social brain has been shaped by natural selection because complex relationships enhance our chances of survival, more sophisticated social groups not only allow for but require larger brains. That in turn allows a greater variety of adaptive responses in and across diverse environments.2 Bonding, attachment, and caretaking provide the necessary scaffolding for the prolonged development required to build larger brains.3
Focusing for a moment on the inner workings of the brain, we discover countless neurons combining to form neural networks dedicated to specific functions such as smell and memory. These networks connect with one another, creating the capacity for even more complex abilities, such as remembering the smell of your grandmother’s cooking or your grandfather’s corny jokes that made everyone groan. This process plays out in a dramatic way early in life as children first develop visual abilities and motor skills and later combine them to perform more complex visual-motor skills, such as playing catch.
At a microscopic level, we find that individual neurons are separated by small gaps called synapses. These synapses are inhabited by a variety of chemical substances that allow neurons to communicate with one another. Instead of words or symbols, neurons use tiny packets of neurochemicals that allow them to connect and be sculpted into the functional neural systems that we just discussed. Over vast expanses of evolutionary time, the brain’s ability to build complex systems has grown ever greater to meet our needs for increasing complexity.
When it comes down to it, doesn’t all communication between people, as complex as it is, consist of the same basic building blocks? When we smile, wave, say hello, and hug each other, these behaviors are sent through the space between us via sights, sounds, and touch. These messages are received by our senses and converted into electrochemical signals that quickly travel to our brains. Our brains then respond to these signals and generate messages that we send back across what could be called a social synapse to reach others. As a result of our relationships, millions of changes within and between neurons combine and organize to shape our emotions, our personalities, and the experiences of our day-to-day lives. Through interacting with others, we activate our senses, regulate our brains and bodies, and change the shape of our neuronal structures. We build the brains of our children through our interactions with them, and we keep our own brains growing and changing throughout life by staying connected to others.
Imagine a grandfather putting his grandson to bed, and think about what is being transmitted across the social synapse. They might talk about the day and read a story while lying next to each other. As they read the story together, they share excitement, talk about the characters, and interpret its lesson. They share smells and sounds; the grandfather might move the child’s hair out of his eyes, kiss his cheek, and at the end of the story, say, “I love you, honey.” Positive interactions such as these likely result in increased metabolic activity and neural growth in both of their brains. Their relationship results in a new being—grandson-grandpa—and an internal biological environment in both of them supportive of secure attachment, neural plasticity, and sustained health.
However, as much as we focus on and learn from these internal biological processes, we have to keep in mind that neurons are embedded within our brains, our brains are embedded within our bodies, and our bodies are embedded within relationships. Nature repeats her strategy of combining neurons into functional systems when she combines individuals into families and tribes. In this way, there is a direct connection between what happens within our bodies and in our relationships with those around us. This is why people are healthier and live longer if they are engaged in a greater number of positive relationships. It is also important to remember that, although all people are linked together, cooperation and interdependence can be a challenge.
COMPETITION AND LOVE
All the people like us are We, and everyone else is They.
Rudyard Kipling
One of my earliest childhood memories is of a scene from an old black-and-white movie. Burned into my mind is the image of an Eskimo family traveling across the tundra in a snowstorm. The children, packed deeply into a sled, are followed on foot by their parents and their maternal grandmother. It is bitter cold, and the wind-driven snow cuts their faces as they push forward.
As the camera pans out, it becomes obvious that the grandmother is lagging behind as the gap between her and her family gradually increases. As the camera continues to pan out, we see a pack of wolves following strategically at a distance. The old woman eventually stops in her tracks, and her children, sensing her absence, stop to look back at her. Pan in close to their faces. Her expression lets them know she is ready to stay behind, and after the family’s brief gesture of goodbye, the sled moves on. Pan out wide. The old woman is motionless as the sled shrinks in the distance and the wolves cautiously approach.
I was horrified! How could her family leave her behind? I ran to tell my grandmother. She listened closely as I breathlessly told her every detail I could remember. When I was done, she tried to explain to me that some families don’t have the luxury of taking care of old people. “Life was very hard for the Eskimos. There wasn’t much food, and children must always come first. That’s the law of nature.” I didn’t find her words the least bit comforting. Agitated and upset, I told her that I would never leave her behind in the snow for the wolves to eat. “But the wolves have to eat too,” she told me. “Let them eat cheese!” I said as I stomped away. “I hate that stupid movie.” As an adult, I understand what she was trying to teach me, but I still don’t like it.
Respect for the aged based on their experience and longevity has been found to be essentially universal in primitive cultures.4 This reverence continued into the early history of Western civilizations and in the formation of Rome and Sparta. The Senate of Rome (from the Latin senex, meaning aged) and the Gerusia of Sparta (from gera, meaning old) reflect the carryover of the tribal authority of elders into the origins of the first Western governments.5 But despite the traditional authority of age, the generations are also in competition for resources, respect, and power.
As my grandmother hinted, even if the elderly are revered, they are expected to contribute to the group. When they are no longer able, due to mental or physical disability, they become a burden, and attachments become strained. In some cultures, abject dependency is a stage of life considered to be “beyond elder,” when people are thought to be overaged, dying, or already dead.6 In some tribes these people are encouraged to commit suicide, participate in rituals during which they will be killed, or are abandoned by the tribe to the elements. Are these ancient customs precursors of our present strategy of warehousing the elderly in nursing homes?
Over the last two centuries, economic, demographic, and cultural shifts in Western society have greatly altered the relationship between generations. Prior to the invention of retirement, most people worked until they died. During the early 1800s, life expectancy in the United States was around 60 years. Life was hard, and most people expended all of their energies in day-to-day survival. Over the next century and a half, cultural changes had a huge impact on both longevity and lifestyle. By 1950, life expectancy had increased by 10 years, most children were out of the family home while parents were still in their 40s, and planning for retirement became a normal aspect of middle-class life.
During this period, the shift from an agrarian to an industrial society tilted the balance of wealth and power to a small group of elders. In agrarian societies, the family resources are tied up in land, buildings, and equipment that are shared by all generations. In industrialized societies, resources are possessed by individuals and can be used by older adults for their exclusive purposes. After a few generations of industrial growth, a relatively small group of elders in America grew to hold a disproportionate amount of the wealth. This trend has continued today via the banking, real estate, and technology industries.
On the other side of this shifting economy are a vast number of older adults who depend on benefits paid for by the working young. As we all know, the present system of Social Security in the United States is growing less viable. In 1945 there were 42 workers to contribute to the benefits of each retiree. By 1965, the number of workers was down to four, and by the year 2000, down to three.7 Only so much of this disparity can be made up for by increasing productivity. The potential longevity and dependency of a large portion of today’s older generation will, of necessity, impact the relationship between the generations. This is, of course, if older adults are as dependent as they are thought to be. As we will see later, new research suggests that older adults contribute more and require less than we have been led to believe.
THE EVOLUTION OF COOPERATION
Great discoveries and improvement invariably involve the cooperation of many minds.
Alexander Graham Bell
As we look back through time to discover our cultural origins, human voices soon fall silent. Beyond the few thousand years since the appearance of the written word, the only direct evidence we have of human culture are the bones and artifacts of our distant ancestors. We add to our knowledge by comparing our brains to those of other species and our behaviors and rituals to those of other cultures.
My first contact with the notion of evolution came during elementary school field trips to the natural history museum, which always included a visit to the “caveman” exhibit. We filed past life-size dioramas depicting scenes of hunting, tool making, and cooking in a series of musty, mahogany-paneled rooms. Some of the cavemen were eating leaves and grinding grain into meal, while others were building fires and sharpening rocks into tools and weapons. We were told that as humans got smarter, they were able to kill and cook bigger animals, consume more protein, and grow larger brains. These brains allowed them to invent more sophisticated weapons and become more efficient killers. The survival of the fittest seemed to mean that those who could run the fastest, jump the highest, and build the most deadly weapons would be the ones to survive.
It turned out that this interpretation of the survival of the fittest had everything to do with the propaganda of the Cold War but little to do with evolutionary theory. For Darwin, fitness wasn’t a matter of physical fitness, but the goodness of fit between an animal and its environment. Each niche has factors, such as food availability, temperature, and water supply, to which living things need to adapt in order to survive. Natural selection directs the course of genetic evolution over generations through the survival and reproduction of those who are the best fitted for the demands of each particular environment. So while you and I may be a good fit for the suburbs of Cleveland, we would be a bad fit for living underwater or on the Arctic tundra. For those environments, an octopus or penguin are fitter than we are, no matter how many push-ups we can do.
Another important bias in these dioramas was that survival was depicted as depending on the strength of the men and not the sophisticated caretaking capabilities of the women. Women were depicted as being almost incidental to the expanding brain size of the ever stronger and smarter men. In fact, it was the evolution of the social brains of the women that allowed for the sophisticated care of the ever less mature children they were giving birth to. Where would these brave male hunters be without them? It is the complexity of the group and the differentiation of the male and female brains that allowed for the level of adaptational flexibility that human groups attained. Obviously, ageism isn’t the only prejudice that guides scientific theory.
For humans, our brains are our most important survival tool, and relationships are our primary niche. This is why emotional nurturance, attachment, and specialized caretaking are central to the evolution of the social brain. Without dedicated and emotionally attuned caretaking, there would be no tool making, abstract reasoning, or culture. And improving the quality of life at this point in our evolution requires that humans are able to recognize and embrace the primacy of attachment, compassion, and wisdom. These have always been central to the way that elders contribute to tribes.
Consistent with what has likely gone on for untold generations, it has been estimated that over 14 million seniors provide care and attention for their children and grandchildren in the United States. At an average of 13.7 hours each week, their annual contribution to the social economy has been estimated to be somewhere between $17 billion and $29 billion.8 This contribution, often unaccounted for and taken for granted because no money changes hands, would be difficult to impossible for many families to replace with hired help. This was certainly true in my family. After getting married in her early 20s, my paternal grandmother never again brought home a paycheck. Yet she nurtured us and served as a model of love and caring for her children, grandchildren, and great-grandchildren. She was central to the social economy of our family and our monetary economy by keeping the rest of us going.
As men grow older, they often become more nurturing, softer, and dare I say, more feminine. Growing up, it was my grandfather who had the time and patience to answer my endless questions, let me win hundreds of games of checkers, and tell me stories of his youth. My father, then in his mid-20s, was busy building a career and forging his identity. My father and grandfather didn’t always see eye-to-eye; my grandfather tried to get my father to follow his advice while my father exerted his independence. My grandfather and I, free from father-son tensions and expectations, adored each other and formed a strong alliance. It has been said that the reason grandparents get along so well with their grandchildren is because they share a common enemy—the middle generation. There may be some truth to this.
The fact that my grandfather lived well past child-rearing age gave me a crack at being fathered in a way that my own father could not provide. Those countless hours are still inside of me and help me to feel valuable and to nurture others. Those hours were an investment in the social economy of our family, part of the reason I stayed in school, and how I was able to cope with the stress and strain of daily life. Many years later, I volunteered to be a Big Brother and was paired with an 8-year-old boy to whom I gave the same kind of consistent care and attention that my grandfather gave to me. I sat with him, answered thousands of questions, and simply gave him my time. We are still in touch 50 years later, and he tells me he feels many of the same things for me that I feel for my grandfather. Now with my son, I often feel my grandfather inside me as I pass on the gift of time, affection, and love to him.
Our increased longevity, hard-won wisdom, and deeper self-awareness are resources we can invest in others. A new conception of aging that incorporates these traditional, noneconomic contributions to the family requires revised myths, new heroes and heroines, and stories of wise and compassionate elders who are available, loving, and nurturing. Let me suggest a vision of the wise elder as a resource who possesses emotional intelligence, is securely attached, and deeply enjoys connecting with others—in essence, the embodiment of what we all need from others to grow physically, psychologically, and spiritually strong. A wonderful gift of evolution is that an ongoing investment in nurturing other human beings is also an investment in our own health and longevity. Thus, a sustained contribution to our tribe is part gift, part obligation, and part self-interest. Perhaps looking back at an old myth will help to inform the new story of aging we need to create.
THE THREE SISTERS
Alone we can do little. Together we can do so much.
Helen Keller
While Western society promotes the perfection and independence of the individual as their highest accomplishment, primitive tribes were mainly concerned with the interdependence of their members. It is clear to those who live in subsistence cultures that survival is a team sport. We find an example of this in the creation myth of the Iroquois where corn, squash, and beans are referred to as the three sisters. The three sisters provided the Iroquois the carbohydrates, protein, and vitamins they needed for survival.
In late spring, we plant the corn and beans and squash. They’re not just plants —we call them the three sisters. We plant them together, three kinds of seeds in one hole. They want to be together with each other, just as we Indians want to be together with each other. So long as the three sisters are with us we know we will never starve. The Creator sends them to us each year. We celebrate them now. We thank Him for the gift he gives us today and every day.9
The three sisters represent a common form of companion planting—a farming strategy that places plants in proximity for mutual benefit. The corn grows straight and tall, providing a solid structure on which bean vines can grow, as well as shade and protection from pests that attack its two sisters. With its broad leaves and chemical secretions, squash conserves water, provides ground cover, and controls weeds. Beans have prickly vines that deter animals and, through a symbiotic relationship with rhizobium bacteria, take nitrogen from the air and convert it to a nutrient on which the corn thrives. Together, the three sisters enrich one another and prepare the soil in ways that enhance next year’s planting.
Like the three sisters, the three human generations of an extended family have traditionally been interdependent and mutually supportive. In countless ways, the presence of each generation helps the other two. But just as the development of industrial farming led us to forget natural methods of companion planting, the value of intergenerational companionship has faded from many of the nuclear families in our modern world. Children provide the family with meaning, a shared focus, and a connection with the future. Parents support the family through childbearing, parenting, and hard work. Grandparents contribute their time, work, wisdom, and provide attachment, bonding, and support to their children and grandchildren. Like the three sisters, each generation stimulates the brains of the other two in ways that promote health and emotional well-being.
We have gone though a century when advances in culture, technology, and communication have overshadowed basic human experience. At the beginning of the 21st century, we are once again discovering the importance of attachment, self-awareness, family, and community. We have to ask ourselves: Do we cherish and celebrate our elders like Madame Calment, or do we leave them to the wolves? Do we encourage relationships between our parents and children, or do we isolate the generations for the sake of efficiency and convenience?
The generations need to interact with one another, not just for pleasure but for mutual nourishment that will help them both to grow and flourish as social beings. Young people need to be reminded that they will one day be old, just as older people need to be reminded of the child that still lives within them. As we will see, considerable evidence supports the theory that secure attachment and sustained relationships result in both better early development and healthy aging. The fundamental need to connect, interact, and love is as powerful at 100 as it is at birth.
LOVE AND LONGEVITY
Age does not protect you from love, but love, to some extent, protects you from age.
Jeanne Moreau
I’m sure you have seen hundreds of books promising the secrets of how to stay young. Most of these books are written by epidemiologists who explore the behaviors, biologies, and lifestyles of large groups of people. Based on their work, we have learned people who don’t drink and smoke live longer, and those who do crossword puzzles and engage in stimulating and challenging professions are less likely to lose their memories. Exercise and fish oil, good; sloth and French fries, bad.
An epidemiologist with a slightly different twist is David Snowdon.10 In his book Aging With Grace, he describes his long-term study with the School Sisters of Notre Dame, a group of nuns who came to Snowdon’s attention because of their unusual longevity and low incidence of dementia. His aim was to discover the relationships between the sisters’ sustained brain health and factors such as intelligence, diet, and exposure to environmental toxins. The sisters were of special interest to him because of the homogeneity of their environment and the wealth of historical information available about them.
Hundreds of nuns agreed to participate in Dr. Snowdon’s study, and the majority agreed to bequeath their brains to him for anatomical analysis upon their deaths. Like most epidemiologists, Snowdon searches among biochemical, environmental, and lifestyle correlates to better understand the causes of diseases, in this case, dementia. As Snowdon began to analyze his data, he found that healthy longevity correlated with having obtained a college degree. While this finding was not new, it was of special interest with the sisters. In the general population, not having a college degree also correlates with smoking, substandard housing, less health care, and lower socioeconomic status, making it difficult to tease out if the lack of a degree is, in itself, meaningful. With the sisters, however, all of these factors were controlled for by their common lifestyle and general lack of vices. The lives of the sisters suggested that something related to having a college degree may be directly related to sustained brain functioning later in life.
Still on file were the personal statements written by these nuns as part of their initial vows five or more decades earlier. When Snowdon examined these essays, he found that those with richer vocabularies in late adolescence and early adulthood were less likely to develop dementia. This finding led to an analysis of the complexity and depth of the content of these essays, both of which were found to be related to higher cognitive functioning later in life. These findings suggest that dementia may not begin in late adulthood, but may be a lifelong process that begins in childhood or adolescence.
An alternative explanation is that people who start off bright and approach life as an ongoing learning experience continue to build new neural structures that cushion them from the effects of dementia. That is, stimulating and challenging your brain from early in life allows your brain to be more resistant to dementia and other diseases. Upon further analysis, Snowdon also found that a correlation existed between longevity and emotional expression in the nuns’ essays as young women. This led him to suggest that intelligence and the capacity to articulate your emotions may both have a relationship to sustained brain health.
I smiled often while reading Aging With Grace because of the way Snowdon wrapped his scientific findings in a love letter to his research subjects. He clearly cared a great deal for them, and the feelings appeared to be mutual. He described the nuns as having become part of his extended family, while he became like a favorite nephew, receiving gifts of hand-knitted mittens and being included in their prayers. As I read further, the deeper meaning of his research began to emerge. The connections the nuns have with one another and even with the young researcher are part of the story. The respect, consideration, and caring they showed to one another may be powerful medicine. I began to think to myself, “Measure caring! Measure love!”
Snowdon grew closer and closer to the treasure and, by the end of the book, he transcended the boundaries of his scientific training. Describing his observations of the nuns’ shared meals, he says:
What I know for sure is that nutrition for healthy aging is not just about eating certain foods or downing a certain number of milligrams of a prescribed number of vitamins each day. It also depends on where we eat, whom we eat with, and whether the meal nourishes our heart, mind, and soul as well as our body.11
From my perspective, Aging With Grace is a story of how the interweaving of the sisters into a lifelong extended family influenced their health, brain functioning, and longevity. I believe that all members of the community, healthy and ill, benefited by their interactions and commitment to one another. We might go further to speculate about the effects of Dr. Snowdon’s relationships with the nuns on his future health and longevity. I doubt he left unaffected by their caring and warmth.
ONE LOVE
You must be the change you wish to see in the world.
Mahatma Gandhi
Although searching for the connections between health and longevity is important, there is a deep and abiding story beneath the statistics. The key to the story is that the brain is a social organ that evolved to survive and thrive while interwoven with other brains. We will explore this deeper story—the life of the social brain—from the perspective of interpersonal neurobiology. Interpersonal neurobiology is grounded in the recognition that humans are best understood when studied in relationship to one another. This relatively new field emerged from an interest in the application of neuroscience to our experiences as parents, therapists, and teachers.
From birth until death, each of us needs others to care for us, help us to feel safe, and give us a reason to live. Regardless of age, relationships join people together in interactions that stimulate, build, and change the brain. In examining these lifelong processes, we will utilize findings from the neurosciences, evolutionary theory, cross-cultural studies, and developmental psychology. Through this exploration we seek to discover the workings of experience-dependent plasticity, or the ways in which the brain is constructed, regulated, and changed by our experiences with others and the world around us. We will explore how relationships impact our brains, which kinds of relationships foster brain health, how relationships make us happier and healthier, and how the brain responds to changing social demands.
The vital link between interpersonal experience and biological processes within the brain makes us particularly interested in the impact of relationships throughout the life span. The nurturance we receive from early caregivers can set us on a course of physical and psychological health, just as interactions throughout life are a primary source of brain regulation, growth, and healing. Friendships, marriage, psychotherapy, parenting, grandparenting—in fact, any meaningful relationship at any time of life—can activate neuroplastic processes, changing the structure and function of the brain.
Put in a slightly different way, human brains depend on connection and communication to survive and thrive. Stimulation, challenge, and being needed by others tell the brain to be alert, learn new things, and stay in shape. Lack of stimulation, repetitive routines, and isolation tell the brain to direct the body’s energy elsewhere. While many of us work hard to earn the right to be comfortable and avoid challenge in later adulthood, this strategy runs the risk of sending our brains the message that they no longer need to grow. From a neuroscientific perspective, this is probably the worst message you can give to your brain. Fortunately for us, our children and their children need us to help build their brains, hearts, and minds. Our continued participation in the cycle of life and our ongoing contribution to the social economy are exactly what we need to maximize the quality of our own lives.
Based on these premises, I believe that a core component of ongoing health and longevity lies in the power of sustained intimacy, attachment, and learning. It is the power of being with others and staying engaged in taking on the challenges of life that builds, shapes, and sustains our brains. The best overall environment for a healthy brain is one that optimizes challenge and maximizes attachments. Therefore, how we think about aging, maintain our relationships, and stay connected to others are all vital aspects of our continued health and longevity.