As a young and promising marine biologist, Camilo Mora led a team of 55 scientists assessing the rapid decline of fish on the world’s coral reefs. It was a global enterprise with broad implications. Hundreds of millions of people rely on reef fish for their primary source of animal protein. Healthy reefs protect coastal communities from devastating storms and provide a multitude of livelihoods, including jobs in the fast-growing tourism industry.

1: Community health worker

MBALE, UGANDA – JULY 21: Community health worker during a home visit, providing family planning services and options to women in the community. This proactive program is supported by Reproductive Health Uganda. July 21, 2014 in Mbale, Uganda. (Photo by Jonathan Torgovnik/Reportage by Getty Images)..

To figure out why so many reef fish are in trouble, Mora plugged all of the possible factors into a massive data-driven analysis. One reason stood out from all the rest: the density of nearby human population. The more people who live close to the reef, the steeper the plunge in the abundance and diversity of fish. And those countries with coral reefs are all on the fast track to doubling their populations in this century.

What happened next gave Mora an insight into why population has become a taboo topic—often avoided, if not intentionally ignored—in peer-reviewed literature, scientific conferences, and academic discussions.

Mora drafted a conclusion suggesting improvements for reef management to confront overfishing, coastal development, and pollution “as well as long-term strategies (improvements in education, empowerment of women, family planning, poverty alleviation, etc.) to curb the growth of coastal human populations.” Then he sent the draft to his colleagues for feedback.

One of the other authors objected, suggesting that the paper instead should recommend setting aside larger proportions of these reefs as marine protected areas. Then another chimed in, supporting an alternate conclusion. So did others. There was widespread discomfort around the topic of population pressures. The revolt of his scientific colleagues took Mora by surprise.

How could they ignore the most striking evidence from the data? Mora asked.

How could they ignore the most striking evidence from the data? Mora asked. Wasn’t his proposed recommendation the most logical, the most obvious conclusion?

Mora soon learned about an overriding fear among scientists of straying from their narrow scientific field—especially if it meant drifting into the fraught issue of a rapidly growing human population.

“All of them were arguing that it was too hot of a topic, as a concluding remark of the paper. It was not our place or responsibility to suggest it as one of the solutions. They didn’t want to deal with the controversy,” Mora recounted. “I was saying, ‘I’m sorry, I’m not suggesting anything crazy. Let’s start investing in human development to reduce the growth rate of population.’”

In the end, Mora won the debate on purely scientific grounds, and his conclusion was published as he had written it. It probably helped that Mora made his case with a heavy Spanish accent, revealing roots in Colombia before moving to Canada to pursue a PhD. It gave his co-authors political cover.

The experience drove Mora to write another article showing how population has been downplayed or trivialized in other research into preserving biodiversity and improving human welfare. He ignored warnings of colleagues who urged him not to publish it and who suggested that he was too junior of a scientist to weather the potential stormy backlash.

Mora’s story is far from unique.

Mora’s story is far from unique.

Dr. Ndola Prata, a public health professor at the University of California at Berkeley, removed her name in protest from an article after her collaborators stripped out a key point she wrote connecting the need for contraception to population growth, an unsustainable ecological footprint, as well as persistent problems with maternal and child health.

Prata chalked up this and similar experiences to Western guilt: the fear among academics and researchers from wealthy industrialized nations to blunder into a socially or culturally sensitive issue confronting the world’s poor countries. The academic taboo, she said, results in inconvenient or uncomfortable words left out of articles and public lectures.

Prata speaks about sex, human reproduction, and contraception in a candid, matter-of-fact way, befitting a female physician from Angola who has spent decades working on reproductive health issues. In late 2014, Prata was asked to join other university experts at a symposium to talk about global health action on a “crowded Earth.”

Prata was amazed how researchers waltzed around the “crowded” part, focusing on everything else: water, sanitation, disease, hunger, and even the need for genetically modified crops to boost food production. “Nobody brought up family planning,” Prata said. “When I had the microphone, I said that one way we could help alleviate these problems is to focus on rapid population growth.”

Initially, her comments brought apprehensive looks among other panelists. Then, a member of the audience asked the speakers: If they had $100 million to make progress on public and environmental health problems, where would they put their money for maximum benefit? “I said family planning would be the best use of the money,” Prata recalled. “And everyone on the panel agreed.”

Prata wishes she would see more “guilt-free researchers” help bridge the population-environment research divide.

Prata wishes she would see more “guilt-free researchers” help bridge the population-environment research divide, given that roughly four out of five U.S. scientists recognize that population growth strains natural resources, according to a recent survey of members of the American Association for the Advancement of Science. “I don’t need to convince them that population is a factor. They know. I need to convince them to say it.”

Survey of members of the American Association for the Advancement of Science

Even if researchers are willing to address it, their message can get obscured, distorted, or lost among audience members with strong views on touchy topics.

Usman Khan, while pursuing a PhD in civil engineering at McGill University in Montreal, Canada, decided to assess the rate of release of estrogens and other human hormones into surface waters in the United States, after having been flushed with urine and feces into sewage systems and ultimately into adjacent rivers and estuaries. The trend has been implicated in the feminization of male fish, with a consequent impact on their ability to reproduce. Some scientists have focused on excess hormones excreted by women using birth control pills, prompting some European lawmakers to consider regulating hormonal birth control as an environmental pollutant.

Working with his doctoral advisor, Dean of Engineering Jim A. Nicell, Kahn took a more comprehensive look at estrogens in effluent in the United States. “There was a knowledge gap that all contraception options have an estrogen load. We wanted to fill that gap.” So they meticulously quantified the load of estrogens from oral contraceptives released into the environment, but also the estrogens that women produce naturally and how they excrete them at far higher levels during pregnancy.

Factoring in the fact that roughly half of U.S. pregnancies are unintended, the researchers ran scenarios with various forms of birth control and failure rates. They determined in an article published in early 2014 that the collective use of contraception in the United States averts 8.8 million unintended pregnancies a year and avoids the release of tons of additional estrogens by pregnant women into U.S. waters. Moreover, if American women’s need for contraception were met, it would further benefit the environment by reducing estrogens by about another 13 percent.

Before publication, Khan presented his initial findings at a green chemistry meeting, packed with mostly women scientists. “There was a palatable increase in tension when he stood up,” Nicell said, recalling the event. “There was a sense: here’s a Pakistani male engineer about to make a pronouncement on women’s contraception.”

Nicell was well aware of the sensitivity of the subject, but he was amazed at how trained academics reacted. “The door was slammed shut before he even started talking,” he said. The audience seemed to miss the results that oral contraception has a net environmental benefit. What they seemed to hear was, he said, “How dare you engineers, focused on the environment, tell me what I can or cannot put in my body. What they didn’t hear was that any attempt to ban the pill would have a negative effect on the environment.”

All these scientists are among the brave ones.

All these scientists are among the brave ones, willing to pursue key scientific questions and present the evidence that answers them, even when the results bump up against political sensitivities or invite criticism. Prata seems to speak for all of them when she said, “We are scientists. If we don’t do it, who will?”