In 2019, a team led by co-author Dr. Barbara Rehermann of the National Institutes of Health found that "wildling" lab mice raised with gut microbes like those of wild mice do a better job of modeling human immune responses than traditional lab mice.

Carr, too, could have been a wildling.

Researchers have now compared the allergic immune response in 'dirty' wildling mice to those of typical clean laboratory mice.

On the contrary, wildling mice developed robust signs of pathological inflammation and allergic responses when exposed to allergens.

The wildling mice are genetically identical to clean laboratory mice but are housed under seminatural conditions and have rich microbial exposures from birth.