A fascinating study recently published in Science found that human lives may depend on the fate of bats. Not directly, of course. Rather, it’s the bat’s unique role in the ecosystems they inhabit that’s important for us. As a result, the decline of bat populations endangers human populations in an unexpected manner. The link between bats, chemicals, and human infant mortality unearthed by the study reveals to us the complexity of the world we inhabit and the danger that ensues when nature’s patterns are drastically upset—whether by us or by some other force.

Eyal Frank, the author of the new study, is an environmental economist at the University of Chicago who saw an opportunity for a wide-scale investigation of how a drastic drop in the population of one species can affect other species. Frank’s work centers around a disease affecting bats: white-nose syndrome, which is caused by the fungus Pseudogymnoascus destructans. Hearing a name like destructans, you know it’s bad.

In fact, it’s considered one of the worst wildlife diseases of the modern era since it has killed millions of bats across North America. The fungus manifests as a kind of white fuzz on the bats’ faces (hence the name—“white-nose syndrome”). Bizarrely, the fungus makes the bats excessively active during hibernation, thus burning up fat that they need to survive.

First appearing in the U.S. around 2006, the fungus most likely made its way to caves near Albany, New York—the locus of the outbreak—by attaching to the clothes and equipment of cave explorers. Now, it’s present in at least 40 states. Infected populations of bats decrease dramatically, or sometimes even vanish altogether, like dark shapes in the night.

When Frank learned about the widespread devastation of bat populations, he saw an opportunity to study the effects of bats on both ecosystems and human societies. As he told The New York Times, “Reading how this disease is spreading from county to county, decimating bat populations, made my economist senses go, ‘Oh, this is probably the best natural experiment you can have.’” It was the perfect opportunity to examine how bats affect human populations either positively or negatively.

What he found was shocking: In U.S. counties where bat populations have been dramatically decreased by white-nose syndrome, human infant mortality spiked 8 percent. Frank thus estimates that over 1,300 infant deaths between 2006 and 2017 are due to the decline in bats.

Why?

Frank’s research indicates that the bats’ diet has a positive impact on us. Bats eat up to 40 percent of their body weight in insects every night, consequently helping to keep insect populations in check. Without the bats, the bugs increase, and farmers end up using more chemical insecticides on their fields. Frank identified that in the counties with high levels of white-nose syndrome, farmers used 31 percent more insecticides, on average.

The problem, of course, is that insecticides are highly noxious. When they’re spread over fields, they enter the environment, particularly through runoff, leaching, or seepage into groundwater. These toxic chemicals then negatively affect pregnancies and the health of infants.

With birth rates already dropping in the U.S., this is no small cause for concern. Some analysts fear that the negative impact of environmental toxins on human reproductive health is one significant factor in the growing fertility crisis. Fertility seems especially damaged in industrialized areas, lending support to the thesis that chemicals involved in the industrial way of life—including industrial agriculture—pose a real danger to us and our future. Recently, concerns over a looming population collapse due to biological, economic, social, and religious factors have become common and mainstream.

So what lessons can we take from all this?

First, we live in a marvelously complex world. The delicate balances that exist within ecosystems should make us marvel. Bats’ impact on bugs and, indirectly, babies shows us this. When that balance is upset by something as seemingly insignificant as a fungus, serious consequences can follow.

This should be a metaphor for human societies as well. Societies flourish when all constituent parts are in harmony, balance, integration. This is one argument for conservatism in general: Don’t disrupt an existing system unless you’re sure you understand how it is currently calibrated and how that calibration will be interrupted by change—and, of course, make sure the change will actually be an improvement to begin with.

Second, there’s a key distinction to be made between working with nature and working against nature. Far be it from me to disdain economic progress or increased efficiency in agricultural production. I am not an environmentalist in the sense that the term is typically used. But progress and productivity don’t always have to involve an insensitivity to the laws of nature.

I think, too often, we go for the quick fix, for an attempt to force nature to conform with our demands, rather than trying to gently coax her. Hence the use of high-powered artificial insecticides to deal with a bug problem. We need to slow down and consider the implications of using artificial methods to bend nature to our will. In this case, one of those consequences is increased infant mortality. And speaking more broadly, there’s good evidence that environmental toxins from the industrial way of life in general are pushing our civilization toward a fertility crisis.

It is always dangerous to fixate on solving a single problem (like large bug populations or low crop yields) while ignoring how the solution affects the existing systems in place, both natural and manmade. The world is more delicate, complex, and interdependent than we often realize.

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