The common origin of all species provides a wealth of history recorded in DNA and a lens for understanding human biology. Immunology research has traditionally used rodents as the model of choice. However, translational success has not met its full potential. Broadening immunology research to integrate comparative approaches across species and environments can amplify the potential of immunology to improve the lives of humans and other animals. Additionally, it can lead to discoveries that are not possible in a restricted set of model organisms and environments. For example, the contemporary vaccine era arose from observing human-animal interactions in a real-world environment (cowpox infection protected milkmaids from smallpox). Most emerging infectious diseases (EIDs) originate in domestic and wild animals (1), and the coronavirus disease 2019 (COVID-19) pandemic is a stark reminder of the need to think more holistically about the health of humans and animals.