Svante Pääbo wins Nobel Prize 2022 in Physiology or Medicine

Swedish geneticist Svante Pääbo (Image: Twitter/@NobelPrize)

Swedish geneticist Svante Pääbo was on October 3 awarded the 2022 Nobel Prize in Physiology or Medicine category by the Nobel Assembly at Karolinska Institute.

The top honour was given to Pääbo, 67, “for his discoveries concerning the genomes of extinct hominins and human evolution", a statement posted on the official website stated.

Through his research, Pääbo "accomplished something seemingly impossible: sequencing the genome of the Neanderthal, an extinct relative of present-day humans", it added.

The Swedish geneticist also made the key discovery of a previously unknown hominin, Denisova, the statement further said.

"Importantly, Pääbo also found that gene transfer had occurred from these now extinct hominins to Homo sapiens following the migration out of Africa around 70,000 years ago," it noted.

This ancient flow of genes to present-day humans has physiological relevance today, for example affecting how our immune system reacts to infections.

Pääbo’s seminal research gave rise to an entirely new scientific discipline; paleogenomics. By revealing genetic differences that distinguish all living humans from extinct hominins, his discoveries provide the basis for exploring what makes us uniquely human, the Nobel Assembly said in a press release.

'Seemingly impossible task'

Pääbo, early in his career, became fascinated by the possibility of utilising modern genetic methods to study the DNA of Neanderthals. However, he soon realised the extreme technical challenges, because with time DNA becomes chemically modified and degrades into short fragments. After thousands of years, only trace amounts of DNA are left, and what remains is massively contaminated with DNA from bacteria and contemporary humans

As a postdoctoral student with Allan Wilson, a pioneer in the field of evolutionary biology, Pääbo started to develop methods to study DNA from Neanderthals, an endeavor that lasted several decades.

In 1990, Pääbo was recruited to University of Munich, where, as a newly appointed Professor, he continued his work on archaic DNA. He decided to analyse DNA from Neanderthal mitochondria – organelles in cells that contain their own DNA. The mitochondrial genome is small and contains only a fraction of the genetic information in the cell, but it is present in thousands of copies, increasing the chance of success.

"With his refined methods, Pääbo managed to sequence a region of mitochondrial DNA from a 40,000-year-old piece of bone. Thus, for the first time, we had access to a sequence from an extinct relative. Comparisons with contemporary humans and chimpanzees demonstrated that Neanderthals were genetically distinct," the press release added.

After initial success, Pääbo took on the challenge of sequencing the Neanderthal nuclear genome. At this time, he was offered the chance to establish a Max Planck Institute in Leipzig, Germany, the release said. At the new Institute, Pääbo and his team improved the methods to isolate and analyse DNA from archaic bone remains. The research team exploited new technical developments, which made sequencing of DNA highly efficient.

Pääbo also engaged several critical collaborators with expertise on population genetics and advanced sequence analyses, the release added. "Pääbo accomplished the seemingly impossible and could publish the first Neanderthal genome sequence in 2010," it further stated.