Is Love of Nature in Our Genes?

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Why does a walk in the woods seem so relaxing? Why do Americans spend $45 billion a year on bird watching? And why will nearly 10 percent of the world’s population visit a zoo or an aquarium this year? The great Harvard University evolutionary biologist Edward O. Wilson had an answer—an inborn human instinct he called "biophilia."

In his 1984 book, Biophilia: The Human Bond with Other Species, Wilson argued that our positive emotional responses to the natural world reflect an inborn and universal component of human psychology. Wilson’s idea caught on. It has, for example, influenced a generation of urban planners and architects. And, since the publication of his book 40 years ago, the term “biophilia” has been cited more than 36,000 times in scholarly publications.

Wilson’s concept certainly rings true to me. As a child growing up in South Florida, I was drawn to the creepy crawlies. I roamed the vacant lots around our neighborhood chasing skinks and searching for snakes and tree frogs. As a nerdy high school kid in New Jersey, I shared my bedroom with an array of exotic pets—which I now look back on with some guilt. Years later, my fascination with the worlds of other species led me to investigate alligator love songs and the personalities of baby snakes.

Source: Image by Hal Herzog

Rethinking Biophilia?

Wilson's theory, however, has its critics. Duke University’s Vanessa Woods and her colleague Melina Knuth recently pointed out in the Journal of Bioeconomics problems with Wilson's basic idea. If, for example, attraction to the natural world is hard-wired in our brains, it should be a human universal—think dancing, language, and thumb-sucking. But it is not. (See Donald E. Brown’s list of human universals.) Indeed, Wilson himself ultimately changed his mind about biophilia being innate. In 1993, he wrote, “Biophilia is not a single instinct, but a complex set of learning rules that can be teased out and analyzed individually.”

In their article, Woods and Knuth proposed a new view of biophilia they call the Biophilia Reactivity Hypothesis. They believe biophilia should be thought of “as a temperament trait, specifically a domain-specific attraction to biodiversity.” And because it is a trait, there should be large individual differences in biophilia. Further, like other psychological traits, biophilia should be “normally distributed”—the classic bell-shaped curve in which most people fall in the middle, with fewer and fewer individuals at the high and low extremes.

Individual Differences in Love of Nature?

Woods and Knuth’s ideas are important. While I am not completely convinced that the term biophilia needs to be redefined as an attraction to biologically diverse environments, their paper got me thinking about why some people are nature lovers and others are not. Surprisingly, there has not been much research on this question. However, Japanese researchers studied individual differences in autonomic stress-related nervous system activities when people were in natural versus urban settings. Most of the 650 young men in their study showed lower levels of cardiovascular stress when they were tested in the forests. However, 20 percent of them were more stressed when they were among the trees than when they were in urban settings. Further, as Woods and Kunths would have predicted, differences in the stress responses in the forested and urban settings fell nicely along the bell curve.

Biophilia in Children?

If biophilia is a trait, we might expect that predilections toward nature should appear at an early age. There has been little research on differences in biophilia in children, but I have seen it in my grandsons, Hudson and Ryland. From the get-go, Hudson was deeply drawn to animals. Now eight, he will spend hours in the little creek near his home flipping rocks for salamanders and catching crayfish, and he has a mental map of the deer trails in the woods around his house. In contrast, his older brother, Ryland, was much less drawn to the wild things. His skills were in other areas—martial arts, math, and football.

Source: Photo by Hal Herzog

The sociologist Arnold Arluke studied children who were unusually attracted to nature. He interviewed kids attending a summer camp that focused on animal care. Arluke called these kids “super-nurturers.” When describing themselves, they used terms like “an animal person,” “animal crazy” or “animal lover.” They said they always remembered being drawn to animals. Their parents agreed. Indeed, they told Arluke they had encouraged and nurtured their children's early concern for other species.

Is Love of Nature in Our Genes?

Individual differences in temperament traits should be stable and influenced by genes. Studies comparing the behaviors of identical and fraternal twins have found that genes play a role in most aspects of human individual differences. These range from basic personality traits (about 50 percent genetic) to sexual orientation (only 30 percent genetic), and dog ownership (58 percent genetic in women, 51 percent in men).

Unfortunately, there are no studies on the relative importance of genes and experience on individual differences in biophilia. However, a study of 1,543 pairs of British fraternal and identical twins found that genes influenced differences in the number of visits to nature parks (48 percent genetic), public gardens (38 percent), and general orientation to nature (46 percent genetic).

A Biophilia Scale?

I am enthusiastic about Woods and Knuth’s ideas because they could usher in new and exciting areas of research. For example, they suggest developing a Biophilia Quotient Scale to measure differences in biophilia.

I can think of a slew of interesting questions such a scale could answer:

• A statistical technique called factor analysis could determine if biophilia is a single trait or is made up of separate components ("factors" in stat-speak)—for example, attraction to biodiversity and a general love of nature.
• Would both animal protectionists and recreation hunters score high on measures of attraction to the natural world? (My guess is yes.)
• How is biophilia related to other aspects of human life—pet-keeping, concern for animal welfare, political views, environmentalism, the Big Five Personality Traits, and others?
• Do high scores on the biophilia scale predict choices in college majors, occupational pathways, or where people choose to live?
• What types of experiences influence differences in our needs to affiliate with the natural world--for example, being raised in the country versus the city?

The list goes on and on.