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New research shows that a rapidly-growing environmental science field—which measures nature's effects on human well-being—has a diversity problem that threatens its ability to make universal scientific claims.

The field—which combines psychology and environmental research—has produced numerous important studies detailing the benefits of nature, forests and parks on human well-being and mental health, including happiness, depression, and anxiety. The findings have been popularized by books like Your Brain on Nature and The Nature Fix, which champion the great outdoors’ health benefits.

But when University of Vermont researchers analyzed a decade of research from the field—174 peer-reviewed studies from 2010 to 2020—they found that study participants were overwhelmingly white, and that BIPOC (Black, Indigenous, People of Color) communities were strongly underrepresented. Over 95% of studies occurred in high-income Western nations in North America, Europe and East Asia—or Westernized nations such as South Africa—while research in the Global South was largely absent. Less than 4% of studies took place in medium-income nations, such as India, with no studies in low-income countries.

This narrow sample of humanity makes it difficult for the field to credibly make universal scientific claims, say the researchers, who published their findings today in .

"This field has great potential to address urgent issues—from the global mental health crisis to sustainability efforts worldwide—but to do so, we must better reflect the diversity of the world's populations, cultures, and values," says lead author Carlos Andres Gallegos-Riofrío of �պ�����'s Gund Institute for Environment.

Just one study in Africa? That's WEIRD

Gallegos-Riofrío credits a of human psychology and behavioral science for inspiring the study. That earlier team, led by Joseph Henrich, highlighted the problem of drawing universal conclusions about human behavior from experiments that primarily used college students from nations that are WEIRD (Western, Educated, Industrialized, Rich and Democratic). Given that most humans live in non-WEIRD nations, with different styles of perception and reasoning and values, Henrich's team argued that WEIRD studies could not credibly support universal scientific claims.

The �պ����� team applied Henrich's lens—but dug deeper into the question of ethnicity for studies of nature's mental health benefits. While they expected a Western bias, they were surprised by the level of bias: sample populations were not only primarily from WEIRD countries—but also overwhelmingly white.

Researchers were also surprised that 62% of studies did not report participants' ethnicity at all (although the team acknowledges some studies used anonymized data sources, such as Twitter). Of the 174 studies, only one study occurred in Africa (South Africa), and one study took place in South America (Colombia)—neither tracked ethnicity. Only one study focused on North America's Indigenous peoples.

"We hope our study is a wake-up call for this promising field that sparks positive change," says co-author Rachelle Gould of �պ�����'s Rubenstein School of Environment and Natural Resources, and the Gund Institute for Environment. "A more inclusive and diverse field that embraces the research needs of the global community—and the full spectrum of ways that humans interact with the non-human world—will ultimately be more impactful."

In addition to studying ethnicity and geography, the team also explored cultural values. They report that many studies conceptualized the human-nature relationship in human-centered, individualistic, and extractive terms, rather than with concepts like reciprocity, responsibility, and kinship, which are more common in many Indigenous and other non-Western cultures, the researchers say.

How to expand the field

The team offers several recommendations to broaden the field: more collaboration with diverse communities, greater diversity of participants, improved demographic tracking, enhanced focus on the Global South, culturally sensitive experiments and tools, cross-cultural research training, and an emphasis on equity and justice. Funding agencies and foundations should encourage greater diversity—of study participants and settings—in their funding calls, the researchers say.

The team also highlights the importance of diversifying environmental science, with better support for students and faculty from diverse backgrounds, and greater collaboration with diverse communities. Research by Dorceta Taylor and others demonstrates that in U.S. environmental institutions, and that the are strongly underestimated.

"We need all cultures working together to tackle the global emergencies we face," says Amaya Carrasco, a co-author and �պ����� graduate student. "That requires understanding what's universal about the human-nature relationship, and what is culturally specific. Those insights are critical to driving social change, and require research to be more inclusive. We need all hands on deck."

The study is titled: “Chronic deficiency of diversity and pluralism in research on nature’s mental health effects: A planetary health problem.” The research team also included Hassan Arab, a graduate researcher at Wayne University.