**1. Introduction**

Systems thinking represents an emerging paradigm in the life sciences. Rather than focus on the functioning of individual parts that make up a larger whole, systems thinking looks at the way in which the parts interact with one another to create the larger whole, and how the larger whole, in turn, regulates the parts which make it up. The back and forth interaction between the parts and the whole is observable and predictable in living systems. Systems thinking focuses on the facts of how the parts of a network interact and under what conditions the patterns of interaction change. Murray Bowen, a family psychiatrist and researcher, applied systems thinking to the human family when he observed, "The family is a system in that a change in one part of the system is followed by compensatory change in other parts of the system" [1] (pp. 154–155). Systems thinking in the natural

sciences has the potential to lead to the formulation of natural systems theories that can predict the functioning of biological units under specified conditions, including the way the unit is influenced by the larger systems of which it is a part and also by its subsystems.

In this article, several examples of natural systems are described as a context for introducing the family as a natural system. We describe the co-regulation of the individual and the family system as conceptualized by Bowen in his theory of the family as an emotional system [1]. We propose a few ideas about the potential value of this view of the family as a natural system to contribute toward progress in science and in addressing human problems in a changing world.

#### **2. Systems Thinking and Natural Systems**

The study of all forms of life has inevitably led to the observation of interactive processes at play both within and between them. The conceptualization of such observations requires some form of systems thinking. As molecular biologist James Shapiro writes "The science of the 21st Century deals with the interactions between multiple components of complex systems, ranging from aggregates of elementary particles to the behavior of the largest structures in the cosmos [2] (p. 145)". The observation of interactive processes occurring from the level of the genome to ecosystems has led to a range of discoveries operating in complex living systems such as those cited below.

Such interactional processes act reciprocally. Two or more variables influence one another as they interact, mutually influencing and modulating each other. For example, at one time gene expression was viewed as a uni-directional process of DNA → RNA → proteins. It is now known that the genome interacts with and can be modified by the cellular and other environmental systems. Research over the past several decades has established that cells have proofreading and repair systems to correct errors when DNA replicates [2].

The emerging field of social genomics has discovered certain types of genes subject to social regulation [3]. Pathways between these socially sensitive genes and neural and endocrine systems influence adaptiveness. Parental care of offspring during the perinatal period can regulate the expression of genes that influence both parenting and the stress reactivity of the offspring across its lifetime. These effects continue for the next several generations [4,5]. In the human, individual genomes operate differently depending on the presence of other people and how they are perceived [6]. Threat and even the perception of threat can influence the expressions of genes related to health and illness. As a result, reciprocal interaction in a family can affect the expression of genes related to the health and illness of every family member.

For much of the twentieth century, the endocrine and immune systems were believed to function autonomously. The discovery that these systems express similar interactional neuropetide and hormonal mediators as well as receptors for these ligands and cytokines led to the further discovery that they represent a highly integrated and interactive system. Understanding the ways in which the nervous, endocrine, and immune systems communicate with one another has led to important new knowledge and new hypotheses about the pathways through which stress impacts adaptive behaviors involved in selfregulation [7,8]. Recognition of the mutual interaction of these major physiological regulatory systems has led to increased understanding of the complexity of such systems.

The study of ant behavior by Deborah Gordon led to the observation that the colonies represented complex adaptive systems that could not be explained by the behavior of the individual ants. It is the interactions among individuals which determine the functioning and morphology of the colony's members. She writes " ... over the last 15 years, it has become clear that many biological systems are regulated by networks of interaction among the components, from genes to individuals. It is colonies, not individuals, that behave in a predictable way [9] (p.46)".

The examples cited above represent only a few of the many discoveries from the observation of interacting entities that had previously been viewed as separate but later determined to be co-regulating components of larger wholes.

#### **3. Co-Evolution of the Brain and the Family**

The shift from focusing on individual entities such as the gene to observing their functioning as interactive components in more complex systems led to the discovery of regulatory processes that could not be observed with a focus on the entities themselves. Observing the brain and the family as they evolved provides a basis for understanding the family as a natural system that regulates and is regulated by its individual members.

Natural systems thinking considers all living systems products of evolution that continuously adapt to their environment. The need of living systems to maintain a stable internal environment amidst adaptive change has resulted in increasingly complex regulatory systems to insure the integrated stability essential for survival. The evolution of nervous systems and the brain allowed the integration of more complex multicellular creatures into single organisms with an increased capacity to adapt to a wider range of environments. For most of human evolution the family has consisted of large extended families, multiple caretakers of infants, and a wide range of social interactions for the developing child. The rapid expansion of the neocortex in the hominid line during evolution may reflect the selective advantage it provided in adapting to the social complexity of life in large clans [10].

The co-evolution of the family and the brain, building on the maternal/offspring attachments of our mammalian ancestors, involved profound adaptations in the hominid biology [11]. The development of the human brain requires a prolonged period of dependency on parents and family members. The development of the neocortex occurs largely after birth. Doubling in size in the last half million years, the human brain evolved in the context of an evolving family interactional system. The human is the only grea<sup>t</sup> ape to exhibit cooperative breeding that involves an increase in the level of social tolerance, greater responsiveness to social signals, and the active parental care of infants by others in the larger group. It is posited that the cooperative care by fathers and other family members, i.e., grandparents, allowed for the prolonged period of development for offspring, as well as a more complex social environment requiring increased intelligence, such as theory of mind, for successful adaptation. As neuroscientist John Allman [12] writes: " ... the development of the brain to the level of complexity we enjoy—and that makes our lives so rich—depended on the establishment of the human family as a social and reproductive unit (p. 2)".

#### **4. The Bowen Theory**

From 1954 to 1959, psychiatrist Murray Bowen led a remarkable research project at the National Institute of Mental Health (NIMH) in Bethesda, Maryland. Entire families with a schizophrenic family member came to live in the Clinical Center for varying periods of time. The researchers observed the families around the clock and kept detailed notes of all interactions. Quickly the field of observation expanded to include the hospital staff as well in their engagements with various family members and with the family as a whole. In a sense Bowen conducted a field study of the human family, recording the ebb and flow of its processes from moment to moment.

#### *4.1. The Family Emotional System*

Bowen proceeded inductively, drawing upon his pool of observational data to formulate theoretical propositions. He quickly realized that the behavior of any given family member is linked to the behavior of other family members. The family behaves as a whole, a unit, analogous to an organism. Deep emotional connections link family members to one another. The emotional connection finds expression in sequences of interactional behavior (patterns) that emerge and recede in conjunction with levels of anxiety and stress in family members. For example, when one person moves toward dysfunction, another appears to increase his or her functioning in compensation. When one person becomes upset, another steps in to attempt to calm things down.

Bowen had discovered what he came to call the family emotional system (FES). Family members appear connected and co-regulated. Within the emotional system, family members display an exquisite sensitivity to one another. They exchange interdependent feeling states and reveal instinctive emotional reactiveness to one another. Interconnected cycles of emotional reactivity produce emerging and receding interactional sequences linked to stress and emotional tension in various relationships. As a part of the FES, family members participate in a perceptual framework held in common. The family psychological fusion includes sets of perceptions and interpretations of one another, of the external environment, and notions of what is to be feared and of how to respond when threatened. In the FES emotion provides motivational energy to family members that is expressed in relationship interactions.

#### *4.2. The Balance of Individuality-Togetherness Forces in the Family*

Bowen proposed that individuals in the family continuously respond to two powerful instincts or forces. The first is to be an emotionally autonomous individual, free from the constraints of relationships to pursue one's own goals and plans. The second is to be connected to others and a part of the group. He called these pressures the "togetherness-individuality forces" [1] (p. 277). Each individual attains a balance between these two forces for oneself. Each family also reflects a broader family balance of these forces. When disturbed, re-balancing or re-stabilizing mechanisms can be observed to come into play to support and restore the balance. These compensatory mechanisms can be likened to the allostatic mechanisms of the organism. They appear to redistribute quantities of anxiety and stress within the system.

The constant pressure on the family to adapt to changing conditions affects the togethernessindividuality balance. Bowen observed that as anxiety and stress increase, family members increase the pressure they put upon one another to remain connected, to see and respond to the challenge in the same way, and to put the family well-being ahead of one's own welfare. In the face of increased togetherness pressure, individuals react emotionally without careful thought. Some give up portions of their individuality in order to comply with the demand for connection and unity. Others may rebel. Yet others may withdraw silently. If prolonged, the family readjusts with a ratio of togetherness to individuality that becomes the new norm for the system.

#### *4.3. Stress and the Level of Differentiation of Self*

Bowen observed that individuals vary in their ability to function when stressed. Some are able to maintain careful thinking they use to guide behavior when pressured. They appear able to maintain their cognitive skills when stressed. Others appear to lose their ability to regulate themselves and rely automatically on instinct or emotion for direction. He proposed a theoretical scale of differentiation of self, placing individual variability in self-regulation and ability to maintain cognitive functioning when stressed on a continuum from those with the least to those with the most ability. The balance of individuality and togetherness reflects the level of differentiation of self. Higher levels of differentiation have a more equal balance between the two forces while lower levels are tilted more toward togetherness.

The level of differentiation of self reflects for any given person the integrated developmental trajectories of agency and autonomy, competency, and maturity. It finds expression in the person's development of principles used to guide behavior, in the ability to regulate behavior in the pursuit of goals, in his or her tolerance for and ability to manage anxiety, stress, and fear, and in the ability to maintain contact with important other people who may have different goals and objectives from his or her own.

The interplay of levels of stress and differentiation of self produce the dynamism observable in human families. Tension (a product of individual and interpersonal anxiety and stress) can best be understood as a load, drag, or strain upon the capability of the family system to maintain itself and adapt to changing conditions. As tension increases in a particular family, the family system responds with set patterns of individual and interactional behavior that appear and recede with stress conditions. These patterns appear to redistribute quantities of anxiety and stress within the system. Vulnerable individuals take on or embody greater amounts of anxiety and stress than less susceptible family members. The more vulnerable family members become those most likely to develop a physical, emotional, or social symptom.

Anxiety and stress levels wax and wane both individually and in the family system. As they go up and down, tension levels rise and fall with them. As tension increases in the family system, behavioral patterns noted above emerge that appear to reflect the tension while simultaneously limiting its effects. Families appear to vary in the amount of tension chronically present in the family system. Some families have little, some a grea<sup>t</sup> deal. A chronically tense family faces current challenge with less reserve capacity to adapt.

#### *4.4. Relationship Patterns in the Family Emotional System*

#### 4.4.1. Patterns Involving Two People

Conflict, distance, and a pattern Bowen described as an "over adequate-inadequate reciprocity" [1] (p. 27) wax and wane, generally within the marital pair in a nuclear family unit. For example, in a particular family system, one relationship (a marital pair, a parent-child duo, a sibling pair) appears to be most sensitive to rising tension. As the tension climbs, the sensitive relationship may display more interpersonal friction. Or they may withdraw from one another, avoiding and not speaking to one another. The patterns of conflict and distance may alternate in the pair. Periods of intense conflict may cycle recurrently with periods of withdrawal. The over adequate-inadequate pattern describes the interlinked behaviors of two people. One functions more competently for the dyad, while the other accepts the inadequate position in order to avoid the discomfort of interpersonal conflict. The more adequate appearing individual appears to gain emotional strength from the posture in contrast to the less adequate person who appears to yield strength.
