The story of Svante Pjabo, the DNA hunter who won the Nobel Prize in Medicine for achieving the seemingly impossible

(CNN) — Swedish geneticist Svante Pääbo won the Nobel Prize in Medicine for pioneering the use of ancient DNA to unlock the secrets of human evolution.

The Nobel committee said on Monday that Pääbo had “achieved something seemingly impossible” when he sequenced the first Neanderthal genome and revealed that Homo sapiens interbred with Neanderthals.

His discovery was made public in 2010 after Pääbo introduced methods to extract, sequence and analyze ancient DNA from Neanderthal bones. Thanks to their work, scientists can compare Neanderthal genomes with the genetic records of people living today.

“Pääbo’s seminal research led to the creation of an entirely new scientific discipline: paleogenomics,” the commission said. “By revealing the genetic differences that distinguish all living humans from extinct hominins, their findings provide the foundation for research into what makes us uniquely human.”

What does the discovery of Pääbo mean?

Pääbo found that most humans today share between 1% and 4% of their DNA with Neanderthals, meaning that Neanderthals and Homo sapiens must have met and had children before Neanderthals went extinct around 40,000 years ago.

Since 1997, he has been working as the director of the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany) and is an honorary researcher at the Natural History Museum in London.

“His greatest contribution was pioneering the recovery of ancient DNA, and that’s extremely important to the study of human evolution,” Chris Stringer, the museum’s head of human evolution research, told CNN on Monday.

Pääbo’s subsequent work to extract DNA from small fossil fragments found in a Siberian cave revealed an equally sensational discovery.

The genome he sequenced showed a species of extinct human, completely unknown at the time, which was named Denisovan after the cave. By comparing Denisova’s DNA with the genetic records of modern humans, Pääbo showed that some populations in Asia and Melanesia inherited up to 6% of their DNA from this enigmatic ancient human.

How does the DNA you found differ from that of Homo sapiens?

“I think the Neanderthal genome is his greatest contribution. He revealed that Neanderthals interbred with us. This has been debated for many years, even by me. But it showed that most of us have ancient DNA (from Neanderthals and/or Denisovans). Stringer added about the Nobel Prize in Medicine.

Some of the genetic traces left by encounters with these two ancient people have medical significance today. For example, a Denisovan version of a gene called EPAS1, which confers a high-altitude survival advantage and is common among modern Tibetans. Pääbo also found that Neanderthal DNA may have played a small role in the evolution of covid-19 infection.

“This is an important scientific discovery in evolutionary biology,” said David Patterson, a professor at Oxford University and president of the British Physiological Society.

“Attributing physiological function to highly conserved mitochondrial genes is important to our understanding of high-altitude acclimation as populations move and adapt to new environments, and how genetic variants affect our daily lives.” Health and Disease, Patterson said in a statement.

Pääbo’s father, the biochemist Sune Bergström, was part of the trio that won the 1982 Nobel Prize in Medicine.

An early passion that culminated in a Nobel Prize for Medicine

Announcing his findings, Pääbo said that “having the first version of the Neanderthal genome fulfills a long-held dream.”

However, his childhood passion was Egyptology after visiting Egypt with his mother, according to a 2008 interview. And one of Pääbo’s early successes was when he was able to extract, clone and sequence the DNA of an Egyptian mummy, work that he secretly at night while doing research unrelated to his Ph.D.

It took Pääbo decades to perfect the process of extracting DNA from ancient fossils, because over time DNA is chemically modified and breaks down into short fragments. This leaves only traces that can easily be contaminated with actual DNA from bacteria and from humans handling the fossils.

His DNA extraction methods have also been applied to the bones of long-extinct animals, revealing insights into the lives of mammoths, cave bears, giant sloths and many other creatures. His team is working on techniques to extract DNA from cave sediments, which will allow scientists to learn about our earliest relatives without having to find their bones: just through the dirt in the caves where they spent time.

Katerina Duka, an assistant professor of archaeological sciences at the University of Vienna who collaborated with Pääbo, told CNN that her work on ancient DNA was as revolutionary for archeology as the advent of radiocarbon dating, which won her the Nobel Prize in 1960 .

“He invented the field. It unlocked many secrets of human evolution,” added Duka.