Svante Pääbo, Nobel laureate in medicine: “Neanderthals lived only 40,000 years ago and knew our ancestors”

Svante Pääbo grew up in a simple house in Stockholm and as a child read all about extinct civilizations. Even after a great rainstorm shook the land around the city, he asked his mother to take him to these places to look for ancient artifacts: he found several pieces of prehistoric pottery, which he decorated his room with. His fascination with the past grew as a teenager when he visited the Egyptian pyramids at Giza. “I really wanted to be an archaeologist. I loved ancient Egypt, but when I started studying at Uppsala University, I realized that my ideas were very romantic. It’s not about discovering pyramids and mummies; everything was focused on ancient languages ​​and progress was very slow. That’s how I ended up studying medicine and completed a PhD in molecular biology,” says Pääbo Trends.

This twist was no mere whim. Its roots lie in the family history of this 63-year-old expert in evolutionary genetics, who would eventually become world famous for deciphering the secrets of the Neanderthals, and who has just won the prestigious 2018 Princess of Asturias Prize for Scientific and Technical Research .The researcher was Karin Pääbo, a chemist from Estonia who arrived in Sweden as a refugee and joined the laboratory of the famous biochemist Sune Bergström. He had a wife and a son, but he was having an affair with Karin. From this relationship Svante was born. The researcher, who died in 2007, never married, and Svante’s father limited himself to taking him for a walk every Saturday in the forest or in places where he would not be recognized: at home, the version is that he works.

Little Pääbo did not mind this routine of an illegitimate child. Although Bergström insists that he tell his family the truth, he never does, and in 1982, Svante has to watch on television the ceremony where his father receives the Nobel Prize in Medicine. In fact, the official son of Bergström, with whom Pääbo gets along quite well today, found out about the existence of his half-brother only after the death of the researcher in 2004. “My father remained distant until his death – says Svante – . We met regularly, but discussed work, not personal matters. He was pleased that I had become a successful teacher. He was interested in my life, but we weren’t close.”

Pääbo, who today works at the Max Planck Institute for Evolutionary Anthropology in Germany, devoted himself to the biological sciences but never forgot his obsession with Egypt: “So as a side project or as a hobby, I started extracting DNA from mummies.” His first steps were taken in the early 1980s, but he kept them secret because his teacher ordered him to focus on the immune system of living people. “I decided to artificially mummify the liver of a calf by placing it in a laboratory oven heated to 50 °C,” Päabo writes in his book Neanderthal: In Search of the Lost Genomes. He then removed the now hard, dry and blackened liver and was able to extract the DNA. This supported his belief that it was possible to study the history of man by analyzing the genes of his ancestors, rather than the morphology of his bones or tools. Finally, Pääbo analyzed several Egyptian mummies until he isolated a segment of DNA from a 2,400-year-old boy, news that became the cover of the magazine Nature in 1985

Pääbo became the founder of the so-called archaeogenetics. “The study of ancient DNA can clarify our genetic history. Of course, this is only one aspect, and in some cases it may not be the most interesting. For example, I think when it comes to ancient Egypt or classical Greece, the cultural history is what interests us the most. But in the case of the more distant past, only the study of genomes and ancient DNA can decipher how our ancestors and Neanderthals interacted when they met,” he says.

Family members

The first Neanderthal fossil was found in 1856 in a cave north of Bonn, an area known to the Germans as the Neander Valley and where there is now a museum. The hominin lineage originally diverged from humans about 500,000 years ago, and fossils show that over time they developed larger skulls, shorter legs, and stronger bodies that allowed them to withstand the Eurasian cold. Not only did they bury their dead, but 65,000 years ago they made the oldest drawings of this type ever found in a Spanish cave in Cantabria. However, about 40 thousand years ago they disappeared after meeting with Homo sapiens which came from Africa and quickly established itself thanks to advantages such as its alliance with the first domesticated dogs, which helped them to hunt much more efficiently than the Neanderthals. Pääbo decided to look for signs of this clash of cultures.

– Is studying mummies and Neanderthals your attempt to decipher what shaped modern man?

– The basis of my interest in Neanderthals is the question of what distinguishes us from them in a genetic and biological aspect. Modern humans, not Neanderthals or other extinct hominins, grew from a few hundred thousand individuals to billions that spread across the globe, developing a rapidly changing culture and technology. What made all this possible? Perhaps one day the answer will be found by comparing the genomes of modern humans with those of Neanderthals.

– Why do these hominids continue to cause so much interest?

– In evolutionary terms, they are the closest relatives of modern man. So if we want to define ourselves from a biological or genetic point of view, we have to compare ourselves to them. They were alive only 40,000 years ago and knew the ancestors of today’s humans, so an interesting question is what happened when we saw each other face to face. In fact, genomes have revealed that we have interbred and had babies together, so if your genetic roots are outside of Africa, then you carry some Neanderthal heritage with you.

This information comes from Päabo’s most famous study. In 2006, he and his Max Planck group announced that they would sequence a complete Neanderthal genome, a project that in 2007 saw him appear on the magazine’s list of the 100 most influential people in the world time. Two years later, the project was completed, and its results shocked the world: Comparing this genome to that of humans revealed that most Europeans and Asians carry nearly 2 percent Neanderthal genes. In contrast, people in Africa do not have this trait. In other words, says Pääbo, Neanderthals never completely disappeared.

“Many studies show that some of the genetic variants that came from them helped modern humans adapt to certain pathogens and other environmental factors they encountered when they left Africa. Other genes have no function and some predispose modern humans to disease,” he says. Thanks to studies by Pääbo and other scientists, it is now known that some Neanderthal genes appear to influence the increased risk of arthritis, type 2 diabetes and schizophrenia, while others make some people taller or more resistant to certain bacteria and viruses.

“We also cataloged genetic changes that occurred in modern humans after we initially diverged from Neanderthals and that occur in almost all modern humans. This list includes nearly 30,000 changes. Among these changes are some that seem to affect the way our brains develop and function,” says Pääbo.

the future of the past

Pääbo, who usually wears shorts and Hawaiian shirts, has an office decorated with a life-size model of a Neanderthal skeleton. But perhaps the greatest testament to his fame is in the cafeteria of the Max Planck Institute, where a photo hangs of him with the singer Christina Aguilera during the Breakthrough Awards ceremony, created by Mark Zuckerberg – the founder of Facebook – to honor great researchers. “When I look back, I realize that it was all a great adventure,” admits Paabo.

This odyssey led him to make another discovery that was as or more impressive than the Neanderthal genome. In 2010, he and his team sequenced DNA obtained from a small finger bone found in Denisova Cave in Siberia. The 41,000-year-old fossils proved that they did not belong to a Neanderthal, but to an entirely new species called the Denisovans. No one knows what they looked like, but it is known that they also interbred with humans: nearly 0.2 percent of the genome of North and South Indians is Denisovan.

– What else is known about them today?

– They likely lived throughout Asia as they contributed DNA to the people who lived in that area. Additionally, nearly 5 percent of the genome in Oceania populations such as that of Papua New Guinea comes from them. Perhaps someone in the future will be able to discover other previously unknown groups from DNA analysis of ancient bones, especially in Asia.

For now, the scientist is enjoying the side effects of his fame. Since it was announced that many people have Neanderthal genes, Pääbo has received dozens of letters from people claiming to be pure descendants of this group. Almost all were men. The only women who wrote to him mainly accused their husbands of being Neanderthals.