The Nobel Prize in Physiology or Medicine was awarded to Svante Pääbo on Monday. The Swedish scientist was lauded for his research in evolution, which worked to connect humans to their evolutionary ancestors. 

Pääbo spent decades analyzing ancient DNA from Neanderthal bones, and eventually published the Neanderthal genome in 2010, The New York Times reports. He also discovered a previously unknown human relative called the Denisova.

Pääbo’s work was likely riddled with challenges. Ancient DNA can be complicated to analyze since it is subject to chemical damage and easily contaminated by bacteria and even the DNA of the scientists studying it, the Times writes. By analyzing the DNA of both humans and close relatives, like Neanderthals, scientists are able to see what makes humans unique genetically, and how humans evolved over time. 

Pääbo also gave rise to an area of study known as paleogenetics, which uses genetic analysis to further understand human evolution, reports The Wall Street Journal. The Nobel community remarked that “his discoveries provide the basis for exploring what makes us uniquely human.”

While the question of what makes humans different remains unanswered, Pääbo’s work has provided a framework for further research. In his memoir, he wrote that he “longed to bring a new rigor to the study of human history” — a feat he certainly accomplished.