How Much of Who You Are Is Shaped by Biology, and How Much by Culture?

NATURE AND NURTURE

Popular discourse in the United States often assigns biology—and usually genes—the primary role in determining who we are. Anthropological research, however, consistently reveals the powerful roles that culture and environment together play in shaping our lives and bodies. Human genetic codes are 99.9 percent identical, so if behavior were entirely driven by our genes, we should expect to find very similar—even universal—behavioral responses to biological influences. Instead, we find remarkable physical and behavioral variety across cultures. Even the most basic human activities, such as eating, drinking, and sleeping, are carried out in remarkably distinct ways. All humans must do these things. But shared biological needs do not ensure shared cultural patterns.

Of course, food and liquid enter the body through the mouth and get digested in the stomach and intestines. But what goes in and how it goes in are other stories. Perhaps you find dog or snake or pony to be inedible, although these are delicacies in other cultures. Many people in China dislike cheese, a staple of North American and European diets. Even how, where, and how many times a day you eat and drink varies from culture to culture. You may use forks, knives, spoons, chopsticks, or hands. You may eat once a day, three times a day, or—like many Americans—six times a day (breakfast, coffee break, lunch, afternoon snack, dinner, midnight snack). You may prefer caviar or a Happy Meal.

Everyone sleeps each day, but some people sleep six hours a night, others eight. Some people take a midday nap. Many college students average six hours of sleep a night during the week and ten on the weekends. Whom you sleep with also varies by culture, with variations including spouses, parents and children, siblings, mothers and children, grandparents and grandchildren. All these patterns vary by culture, and even within a culture they may vary by age, gender, and class. Despite the cross-cultural evidence of human behavioral variation, many people believe that basic patterns of human behavior, intellectual capacity, and psychological tendencies are determined by biology, from warfare and sexuality to the shortage of women in math and science careers.

Most anthropologists have been highly critical of approaches that significantly overstate the importance of a genetic inheritance fixed in deep evolutionary time and that underestimate the role of culture and the environment in shaping human physical and behavioral diversity (McKinnon and Silverman 2005). Although contemporary genetic discoveries are opening up new realms of understanding about human biology, we are not close to linking certain genes or groups of genes with particular behaviors or characteristics. At best, we can imagine these connections based on contemporary patterns of behavior. But it often appears just as likely that contemporary notions of human nature are being projected back onto a mythological version of human prehistory that never existed.

We do have, however, much clearer indications of how cultural patterns and beliefs shape human behavior. In the debate over the origins of gender inequality in the upper echelons of math and science careers, we might look instead to gender stereotyping in the classroom, enculturation of girls, and conscious and unconscious gender bias in hiring and promotion practices. It may feel more comfortable to trace inequality to innate biological differences; a link might enable us to dismiss or excuse the inequality as “natural.” But there is no biological evidence of this link. The current evidence is that these patterns of inequality and stratification are culturally constructed and completely changeable.

FROM HUMAN BEINGS TO HUMAN BECOMINGS

Contemporary anthropological research calls for a much more complex view of human evolution and life span development that incorporates multiple architects of the human physical form and behavior. An emerging synthesis looks at genes as part of a developmental history in which biology and culture are deeply entangled in a dynamic and ongoing biocultural process of change (Fuentes 2013). For instance, the emerging field of epigenetics explores how the environment into which one is born can directly affect the expression of genes during one’s lifetime. In particular, epigenetics examines variations caused not by changes in the actual DNA sequence but by environmental factors that switch genes on and off and affect how cells read genes. These epigenetic marks may change in response to many of the processes anthropologists frequently study—nutrition, stress, disease, social inequality, and migration (Fuentes 2013; Thayer and Non 2015; Wade and Ferree 2015). Additionally, research shows that our bodies do not function in isolation as discrete biological units, despite what our popular culture narratives would lead us to believe. The human body contains approximately 100 trillion cells. About 90 percent are independent microorganisms that live within our bodies and form what has come to be known as the human microbiome. This microbiome plays a key role in many bodily functions, including human digestion, vitamin production, drug metabolism, and immunity (Palsson 2013; Warinner and Lewis 2015). Some scholars suggest that these new ways of thinking about the body and gene expression should lead us to think of ourselves not as human beings—shaped long ago by a completed evolutionary process—but as human becomings who are continually evolving and adapting, both on the species level and within the individual life span (see Ingold and Palsson 2013).

CONNECTING CULTURE AND BEHAVIOR

While direct links between specific genes and behavior have proven difficult to identify, we have much clearer indications of how cultural patterns and beliefs shape human behavior. Culture is learned from the people around us. It is not written into our DNA. Instead, we are born with the ability to learn any culture that we might be born into or move into. We have the ability to learn any language and master any set of beliefs, practices, norms, or values. This may seem obvious, but it is a crucial principle to understand as we examine the many cultural patterns in our own experience that we often assume to be normal, even natural. Such cultural practices are not universal to all humans. Rather, they are uniquely created in each culture. Recognition of this fact allows us to question common assumptions about the biological basis of most, if not all, human behavior, and instead to consider how learned patterns of belief and practice have been created and how they might be changed. Later in this book, in the chapters on race, ethnicity, gender, family, and human sexuality, we will explore the intersections of biology and culture in further detail.

As popular as it may be to think that genetics is the primary driver of our development as humans, even our long evolutionary process has been deeply influenced by culture. Ultimately, it is culture that has made us human and enabled us to evolve physically and in our patterns of relationship with others. For example, with the development of simple stone tools as early as 2.5 million years ago, culture allowed our ancestors to adapt to the world around them. Stone tools (in particular, hand axes and choppers) enabled our ancestors to butcher meat more quickly and efficiently, thereby providing higher quantities of protein for the developing brain and influencing the direction of our physical adaptation. In cases such as these, the power of culture to direct and modify biological instincts is indisputable. Over time, cultural adaptations—from control of fire, to the development of language, to the invention of condoms and birth control pills—have replaced genetic adaptations as the primary way humans adapt to and manipulate their physical and social environments.