The astonishing link between bats and the deaths of human babies

 There are a number of well-known ways to keep babies healthy — wash your hands often, get them vaccinated, don’t smoke inside, and so on.

But there’s one thing you probably haven’t heard of: protecting bats. Like literal flying bats.

That’s one takeaway from a remarkable new study, published in the journal Science, that links the decline of bats to a rise in newborn deaths in the United States.

By compiling and analyzing a huge amount of government data, environmental economist Eyal Frank, the study’s sole author, discovered that in regions with outbreaks of white nose syndrome, a wildlife disease that kills bats, the rate of infant mortality increased by nearly 8 percent relative to areas without the disease.

There’s a clear reason for this, according to the paper. Most North American bats eat insects, including pests like moths that damage crops. Without bats flying about, farmers spray more insecticides on their fields, the study shows, and exposure to insecticides is known to harm the health of newborns.

“When bats that eat insects go down, farmers compensate by using more insecticides,” Frank, an assistant professor at the University of Chicago Harris School of Public Policy, told Vox. “That has adverse health consequences — full stop. The damages from their absences appear to be substantial.”

First, there is a cost to farmers. According to Frank’s study, the decline of bats has cost the agriculture industry nearly $27 billion between 2006 and 2017, as shown by a drop in revenue in regions with white nose syndrome. The reason for this loss is not clear, though it might be that bat-free regions produce lower quality crops, Frank said.

A study published in 2022 supported a similar conclusion, linking the spread of WNS to a drop in the rental price of farmland. The idea is that farmers have a lower yield or have to spend more money to grow crops — such as on purchasing insecticides — when there are no bats providing free pest control. (I interviewed one of the study co-authors, Amy Ando, for an episode of the Vox science show Unexplainable. You can listen here.)

Then there is the serious cost to human lives.

It’s well-known that when farmers spray their fields with insecticides, those chemicals can leach into the environment, where they pose a risk to public health. One recent review links pesticide exposure among newborns, for example, to life-long abnormalities and diseases. With this in mind, you might expect regions with no bats, where farmers are using more insecticides, to have more health issues.

Study: Dead bats are linked to a spike in farm pesticides and infant mortality | Vox