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Medicine Nobel goes to Svante Pääbo: What his research tells us about human evolution

The Nobel Assembly said Svante Pääbo's discoveries on evolution have helped “provide the basis for exploring what makes us uniquely human”.

Swedish geneticist Svante Paabo holds a skullSwedish geneticist Svante Paabo, director of Leipzig's Max Planck-Institute for Evolutionary Anthropology, holds a skull in this handout picture taken in Leipzig, Germany, April 27, 2010. (Image by Frank Vinken/Max-Planck Institute/Handout via REUTERS)

The Nobel Prize for Medicine was Monday (October 3) awarded to Swedish academic Svante Pääbo “for his discoveries concerning the genomes of extinct hominins and human evolution”, according to a press release of The Nobel Assembly at the Karolinska Institute, which gives out the Medicine prize annually.

In a press release, the assembly said: “Through his pioneering research, Svante Pääbo accomplished something seemingly impossible: sequencing the genome of the Neanderthal, an extinct relative of present-day humans. He also made the sensational discovery of a previously unknown hominin, Denisova.”

The prize kicks off the week that will see the rest of the Nobel awards announcements.

Svante Pääbo gets Medicine Nobel Prize: his work, explained

This year, the focus of the committee seems to have been on human evolution and the role that it has played in shaping our health and biological systems over time. Svante Pääbo’s “seminal” discoveries “provide the basis for exploring what makes us uniquely human”, said the assembly.

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Hominins refer to the now-extinct species of apes that are believed to be related to modern humans, as well as modern humans themselves. The release said, “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. This ancient flow of genes to present-day humans has physiological relevance today, for example affecting how our immune system reacts to infections.”

What is the relation between evolution and biology?

In its press release, the assembly said Svante Pääbo established an entirely new scientific discipline, called paleogenomics, that focuses on studying the DNA and genetic information of extinct hominins through reconstruction, and “Pääbo’s discoveries have established a unique resource, which is utilized extensively by the scientific community to better understand human evolution and migration…We now understand that archaic gene sequences from our extinct relatives influence the physiology of present-day humans”.

An example of this linkage is when Pääbo extracted DNA from bone specimens from extinct hominins, from Neanderthal remains in the Denisova caves of Germany. The bone contained exceptionally well-preserved DNA, which his team sequenced. It was found that this DNA sequence was unique when compared to all known sequences from Neanderthals and present-day humans. Pääbo had discovered a previously unknown hominin, which was then given the name Denisova.

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Comparisons with sequences from contemporary humans from different parts of the world showed that gene flow, or mixing of genetic information among a species, had also occurred between Denisova and Homo sapiens – the species of modern-day humans. This relationship was first seen in populations in Melanesia (near Australia) and other parts of South East Asia, where individuals carry up to 6% Denisova DNA.

The Denisovan version of the gene EPAS1 confers an advantage for survival at high altitudes and is common among present-day Tibetans.

What are the challenges in carrying out such research?

There are “extreme technical challenges because with time DNA becomes chemically modified and degrades into short fragments”, said the release. The main issue is that only trace amounts of DNA are left after thousands of years, and exposure to the natural environment leads to contamination with DNA from bacteria and contemporary humans, making research complex. Pääbo started to develop methods to study DNA from Neanderthals and continued doing so for several decades.

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Remarkably, when he managed to sequence a region of mitochondrial DNA from the 40,000-year-old Denisovan piece of bone, it marked the first time researchers had access to a sequence from an extinct relative. Pääbo also successfully engaged several critical collaborators with expertise in population genetics and advanced sequence analyses. His interest in harnessing technological advances eventually accomplished the “seemingly impossible” – the publishing of the first Neanderthal genome sequence in 2010. The release said, “Thanks to Svante Pääbo’s discoveries, we now understand that archaic gene sequences from our extinct relatives influence the physiology of present-day humans.”

First published on: 03-10-2022 at 05:57:40 pm
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