During his childhood in Sweden, Svante Pääbo developed a fascination with archeology, which only deepened after his mother, a chemist, took him to Egypt when he was 13. He wanted to be like Indiana Jones, discovering mummies and other ancient hidden treasures. “I had a very romantic idea of what archeology was,” he recalls. “But when I got to [Uppsala] University and started studying it, I found it wasn’t quite as romantic as I had imagined.”
Pääbo switched from archeology to medicine, influenced, he says, by his father, the Nobel Prize-winning biochemist Sune Bergström. “At that time, if you were in Sweden and interested in basic biological research, you went to medical school,” says Pääbo. He enjoyed clinical medicine, but turned from his medical studies in 1981 to do doctoral research on adenoviruses and their interaction with the immune system. Yet he still had Egyptology on his mind. He wondered if it was possible to obtain DNA from archeological remains. At the time, scientists did not know if DNA could survive intact for a hundred let alone several thousand years. Without telling his PhD advisor (who Pääbo worried might not approve) and with the help of one of his former Egyptology professors, Pääbo obtained tissue samples from a German museum and went to work trying to isolate some DNA from them. His finding— he demonstration that DNA survived in the cell nuclei of some Egyptian mummies—was published in 1984 in a small East German journal, and then again a year later as the cover story in Nature.
One of the scientists who read—and was impressed—with Pääbo’s work was the late evolutionary molecular biologist Allan Wilson at the University of California, Berkeley. Wilson had just announced that his lab had isolated a small section of DNA from a zebra-like animal known as a quagga, which had become extinct in the 19th century. Wilson wrote to Pääbo to ask if he could do a sabbatical in Pääbo’s laboratory. “It was before the Internet,” laughs Pääbo. “He had no way of knowing that I didn’t have a lab, that I was just a graduate student.” Pääbo wrote back to explain the situation—and to ask for a postdoctoral position in Wilson’s lab.
Pääbo began working with Wilson in California in 1987. With the aid of the new PCR (polymerase chain reaction) technology, they analyzed mitochondrial DNA (mtDNA) from a 7,000-year-old human brain. “But we soon came to realize that contamination was a major difficulty,” said Pääbo. The tiniest particle of dust derived from human skin—even from a long-dead museum curator—could ruin the results of their research. Pääbo switched to extracting DNA from non-human ancient creatures, such as mammoths, giant sloths, and the marsupial wolf. That research “helped me work out the techniques and become much more secure in what I was doing,” he says. It also led to some interesting discoveries, such as the finding that moas, the giant flightless birds that were hunted into extinction on New Zealand about 500 years ago, are more closely related to Australian emus than to kiwis, the flightless birds that populate New Zealand today.
Returning to Europe in 1990, Pääbo became professor of general biology at the University of Munich, where he focused on development of techniques to study ancient DNA and started applying them to Neandertals, humans’ closest extinct relative “I wanted to learn how the Neandertals are related to people who live today,” says Pääbo. Using specimens from a German museum, he successfully sequenced mtDNA from a Neandertal upper arm bone. That achievement, which was published in the journal Cell in 1997, is considered a watershed in evolutionary genetics. Pääbo’s results had shown not only that DNA could be successfully extracted and sequenced from Neandertal remains, but also that Neandertals and humans were distinctly different groups that split off from each other about 500,000 years ago.
In 1997, Pääbo was asked to become director of the Department of Genetics at the new Max Planck Institute for Evolutionary Anthropology in Leipzig, a position he continues to hold today. Over the past decade, he has led the challenging effort to sequence nuclear genome of the Neandertals. In 2010, he and his colleagues at the Institute published the draft version of that genome, along with the startling finding that Neandertals and modern humans share up to 4 percent of their genetic blueprint. The finding shows, says Pääbo, that a small number of Neandertals and early humans have interbred. That same year, Pääbo and his colleagues reported a second remarkable finding: A DNA analysis of a finger bone found in 2008 in a Siberian cave showed that the bone belonged to a previously unknown hominin group, which the researchers named Denisovans, after the cave in which the bone had been found. It was the first time a new hominin had been identified by genetic analysis alone. They also showed that Denisovans have contributed DNA to people living in Melanesia today.
Pääbo has also investigated the genetic relationship between humans and great ape populations, particularly how differences in gene expression evolve. “I want to know what happened in the human lineage—in other words, what makes humans special,” he says. Pääbo has identified and studied genes critically important in human evolution, for example FOXP2, which is associated with language development. In 2008, Pääbo reported that the protein encoded by the FOXP2 gene in Neandertals was identical to that of present-day humans, which raised the tantalizing possibility that they may have had language capabilities similar to present-day humans.
Pääbo has won numerous awards, including the Louis Jeantet Prize for Medicine (Switzerland), the Kistler Prize (USA), and the Leibniz Prize (Germany). He is a member of Sweden’s Royal Academy of Sciences, and in 2004 he became a foreign member of the National Academy of Sciences. Pääbo lives in Leipzig with his wife, Linda Vigilant, an American primatologist. They have a son, 7, and a newborn daughter.