Researchers at the Salk Institute, UC San Diego, and Washington University have gathered novel details on undernourished children’s gut microbe populations in the largest study of its kind to-date, identifying dozens of new microbes to form an unprecedented database. They found that gut microbiome diversity and genome stability may be a powerful marker for whether children thrive or suffer. Their findings pave the way for diagnostic and preventative solutions for undernourished children around the globe, while also opening the opportunity for innovations across other public health crises from obesity to malaria to COVID-19.