Eske is an evolutionary geneticist recognized for his studies on human dispersal, microbial long-term survival and evolution, megafaunal extinctions, DNA degradation, and environmental DNA. In 2010 he sequenced the first ancient human genome. He has conducted the first large-scale multi-species ancient population genetic study, and established the field of environmental DNA, where modern and ancient DNA are obtained directly from environmental samples such as sediments, ice and water.
After spending his youth as explorer and fur trapper in Siberia, he established the first ancient DNA laboratory in Denmark. At the age of 33, Willerslev became Full Professor at University of Copenhagen.
Eske is a Lundbeck Foundation Professor and is The Prince Philip Professorship of Ecology and Evolutionary Biology elect at University of Cambridge.