At his lab at Emory University, Jaap de Roode and his team study parasites and their hosts. Some of the questions that intrigue them: If a parasite depends on its host's survival for its own well-being, why do so many of them cause harm? In what ways are hosts able to self-medicate in order to make themselves less desirable to parasites? And are the abilities to harm hosts — and the ability of hosts to self-medicate — favored by natural selection?

The De Roode Lab focuses on the monarch butterfly and its parasites. The team has made a fascinating discovery: that female butterflies infected by a parasite choose to lay their eggs on a specific variety of milkweed that helps their offspring avoid getting sick. De Roode hopes that this insight could lead to new approaches in medications for human beings in the future.