Who is Swante Pabo? 2022 Nobel Prize in Medicine awarded for discoveries in human evolution
 |
| Svante Pääbo–2022 Nobel Prize in Medicine awarded for discoveries in human evolution |
Svante Päboo succeeded in something no one thought possible: he mapped the Neanderthal genome and gave us completely new insights into human history.
The Nobel Prize in Medicine was awarded Monday to Swedish geneticist Svante Pabo, whose work on ancient DNA helped transform our understanding of human origins.
Who is Swante Pabo? 2022 Nobel Prize in Medicine awarded for discoveries in human evolution
Pabo, an evolutionary geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, led the groundwork for sequencing the genome of a long-extinct Neanderthal from 40,000-year-old bone fragments. Anna Wedel, a member of the Nobel Committee, said it was a “seemingly impossible task”.
The work was transformative, showing that Neanderthals migrated out of Africa after being mixed with prehistoric humans, and that remnant of those interactions remain in the genomes of people today. Pabo’s efforts laid the foundation for a new field of science that uses ancient DNA as a new stream of information to investigate human evolution.
Forty years earlier, Pääbo’s father, Sune Bergström, won a Nobel Prize.
As a young scientist, Pabo focused on understanding how adenoviruses interacted with the immune system. But he maintained an interest in human origins and worked on isolating DNA from Egyptian mummies as a side project.
At the time, the ancient DNA field was “kind of a joke,” said anthropologist John Hawkes of the University of Wisconsin at Madison, full of unreliable claims that would be proven false as scientists tried to recover DNA from dinosaurs.
“It was Svante who came along and made it a science,” Hawks said.
For decades, Pabo shrugged off the arduous task of analyzing ancient DNA, devising ways to overcome the technical challenges of working with samples that deteriorated over time and became easily contaminated. They worked extensively on the DNA of extinct animals, but always with the goal of bringing the techniques they were developing to Neanderthals, the extinct, large-brained relatives of modern humans.
Once he developed those methods, he brought together a large consortium of scientists and made the necessary connections to obtain the ancient bone fragments needed to take on the monumental task of trying to understand the genome of Neanderthals.
That work disrupted the prevailing view of human origins. Homo sapiens originated in Africa about 300,000 years ago, but they emerged in a world full of other hominid species – and mixed with them during migration.
Pabo and his colleagues showed that extinct Neanderthals have lived in our DNA for 30,000 years. As modern humans migrated outside Africa, they mixed with Neanderthals, making up about 1 to 2 percent of the genomes of non-Africans today. From a finger bone found in a cave in the Altai Mountains in Russia, they discovered a new species of Denisovans, an early hominid.
The question of man’s origin and what makes us unique has interested humanity throughout the ages. By the end of the 1990s, almost the entire human genome had been mapped through so-called sequencing. For tens of thousands of years, Homo sapiens and Neanderthals lived side by side, but in the 90s no one knew how we were related to the extinct Neanderthals.
It was something that interested the Swedish biologist Svante Pääbo. Already as a doctoral student in Uppsala in the 1980s, he was fascinated by the possibility of studying the Neanderthals’ genetic mass from very old pieces of bone.
Now he alone gets to receive the Nobel Prize because he has succeeded in something that no one else has come close to.
After first practicing on preserved mummies in Uppsala, Svante Pääbo used DNA from Neanderthal mitochondria, which is a part of the cell that contains its own DNA. In this way, Pääbo succeeded in sequencing the DNA from a 40,000-year-old piece of bone.
Ancient DNA
There is DNA in two places in the cell: in the cell nucleus and in the mitochondria. When we die, the DNA starts to break down, and it gets mixed up with DNA from, for example, bacteria. Svante Pääbo has developed methods for extracting and analyzing really old DNA.
Then he went further and tried to map the entire genetic mass of the Neanderthals from the cell nucleus itself. Because DNA breaks down and mixes with bacteria, it was difficult, if not almost impossible, to make accurate analyses. But Svante Pääbo developed a method, or rather a rigorous system, that involved much more efficient sequencing than before, in an environment with minimal risk of contamination.
In 2010, Svante Pääbo finally succeeded in what he himself had previously said was impossible: he had mapped the entire Neanderthal genome. It made it possible for Pääbo and his collaborators to analyze in detail the human relationship with the Neanderthals.
New family trees
Pääbo obtained DNA from Neanderthal bone fragments and from a finger bone from Denisova Cave in southern Siberia. DNA shows that our ancestors had children with both Neanderthals and Denisovans.
They found that 1-4 percent of the genetic mass of living humans from Europe and Asia comes from Neanderthals. This means that Neanderthals and Homo sapiens had children together when they lived side by side.
Then Svante Pääbo made another great discovery: Thanks to a 40,000-year-old little finger bone from the Denisova cave in Siberia, a previously unknown type of human was discovered, which is now called Denisova. Modern people in Southeast Asia, for example, carry up to six percent of Denisovan DNA.
Svante Pääbo’s pioneering research methods have given rise to a completely new field of research: paleogenomics. His research has shown us how our extinct relatives, both Neanderthals, and Denisovans, have influenced our physiology. For example, the gene EPAS1 confers advantages in staying at high altitudes and is common in people in Tibet.
The Genes are mixed
Pääbo’s results show how our ancestors migrated from Africa to Europe and Asia. Today’s Europeans have about 1–2 percent Neanderthal DNA and Southeast Asians have about 1–6 percent Denisovan DNA.
Another gene variant from the Neanderthals is important for our immune system. A few years ago, it was noticed that this gene variant means a 20 percent lower risk of being admitted to the intensive care unit in case of covid-19.
Most Nobel Prizes are usually shared between two or three scientists, but it is Svante Pääbo (and his colleagues) who have refined the methods and been alone in having made the major discoveries.
Svante Pääbo’s discoveries may not have yet led to medical treatments, rather they show how the genes of our extinct relatives affect our physiology today. His research also provides answers to both what separates us and what we have in common with our former relatives.