His projects include studies of belly button biodiversity, mites that live on human faces, ants in backyards, and fungi and bacteria in houses.
At the University of Connecticut, Dunn studied the recovery of tropical forests in Costa Rica, Peru and Bolivia after clear-cutting and use for traditional agriculture.
Upon finishing his PhD, he became a Fulbright fellow at Curtin University in Australia where he worked with Jonathan Majer and Byron Lamont to study the dispersal of seeds.
In Knoxville, Dunn worked with Nate Sanders and studied the biodiversity of the Great Smoky Mountains National Park, which he later wrote about in his book Every Living Thing.
[9] Dunn's work includes studies of parasites of raccoons, bacteria in houses, ants in backyards, giant crickets that live in homes and the biodiversity of belly buttons.
Meanwhile, Dunn's recent writing has considered the quest to find new superheavy elements, why men are bald, how modern chickens evolved, whether a virus can make a person fat, the beauty of the Gulf of St. Lawrence, the biology of insect eggs,[10] the secret lives of cats, the theory of ecological medicine, why the way we think about calories is wrong, and why monkeys (and once upon a time, human women) tend to give birth at night.
Kirkus Reviews wrote of Every Living Thing: "Even sophisticated readers will blink as the author reveals the dazzling diversity of life, its ability to thrive in areas formerly thought barren (miles under the sea, under ice caps, under the earth’s crust, in space), and the ingenuity of scientists searching for it.