The Nobel Prize in Medicine was awarded for research on evolution

This year’s Nobel Prize in Physiology and Medicine was awarded to the Swedish scientist Svante Paabo for his discoveries in the field of human evolution.

Thomas Perlman, secretary of the Nobel committee, announced the winner on Monday at the Karolinska Institute in Stockholm, Sweden.

Paabo initiated research comparing the genomes of modern humans and our closest extinct relatives, the Neanderthals and Denisovans, showing that there was admixture between the species.

The prize in the field of medicine began the week of the announcement of the Nobel Prize. It will continue on Tuesday with the prize for physics, on Wednesday – for chemistry, and on Thursday – for literature. The 2022 Nobel Peace Prize will be announced on Friday, while the economics prize will be announced on October 10.

Last year, David Julius and Ardem Pataputyan were awarded medicine for discovering how the human body perceives temperature and touch.

The prize money is SEK 10 million (almost $900,000) and will be presented on December 10. The money comes from the will of the creator of the award, the Swedish inventor Alfred Nobel, who died in 1895.

THIS IS BREAKING NEWS.

Nobel Committee Press Release: Nobel Prize in Physiology or Medicine 2022

Nobel Assembly at the Karolinska Institute

today decided to reward

2022 Nobel Prize in Physiology or Medicine

to

Svante Piabo

for discoveries concerning the genomes of extinct hominins and human evolution

Humanity has always been interested in its origins. Where do we come from and how are we related to those who came before us? How do we, Homo sapiens, differ from other hominins?

Thanks to his pioneering research, Svante Pääbo has accomplished something seemingly impossible: sequencing the genome of a Neanderthal, an extinct relative of modern humans. He also made a sensational discovery of the previously unknown Denisova hominin. The important thing is that Pääbo also found it gene transfer evolved from these now-extinct hominins to Homo sapiens after migrating out of Africa about 70,000 years ago. This ancient gene flow for modern humans still has physiological significance today, for example by influencing how our immune system responds to infections.

Piabo’s fundamental research gave rise to an entirely new scientific discipline; paleogenomics. Discovering genetic differences that distinguish all living humans from extinct hominins, his discoveries provide a basis for studying what makes us uniquely human.

Where do we come from?

The question of our origins and what makes us unique has preoccupied humanity ever since ancient times. Paleontology and archeology are important for the study of c human evolution. Research has provided evidence that anatomically modern humans, Homo sapiens, first appeared in Africa around 300,000 years ago, while our closest known relatives, the Neanderthals, evolved out of Africa and populated Europe and western Asia from around 400,000 years to 30,000 years ago, at which point they became extinct. About 70,000 years ago, groups of Homo sapiens migrated from Africa to the Middle East, and from there spread throughout the rest of the world. Thus, Homo sapiens and Neanderthals coexisted on a large territory of Eurasia for tens of thousands of years. But what do we know about our relationship with the extinct Neanderthals? Clues can be obtained from genomic information. By the late 1990s, almost the entire human genome had been sequenced. This was a significant achievement that allowed further research into the genetic relationships between different human populations. However, research into the relationship between modern humans and the extinct Neanderthals will require sequencing of genomic DNA recovered from archaic samples.

A seemingly impossible task

Early in his career, Svante Piabo was fascinated by the possibility of using modern genetic methods to study Neanderthal DNA. However, he soon realized the extraordinary technical problems, because over time DNA is chemically modified and breaks up into short fragments. After thousands of years, only traces of DNA remain, and what remains is heavily contaminated with the DNA of bacteria and modern humans (Figure 1). As a postdoctoral fellow with Alan Wilson, a pioneer in evolutionary biology, Piabo began developing methods for studying Neanderthal DNA, a work that spanned several decades.

In 1990, Pääbo was recruited to the University of Munich, where he continued his work on archaic DNA as a newly appointed professor. He decided to analyze the DNA of Neanderthal mitochondria, the organelles in cells that contain their own DNA. The the mitochondrial genome is small and contains only part of the genetic information in the cell, but it is present in thousands of copies, which increases the chances of success. Thanks to his advanced methods, Piabo was able to sequence a region of mitochondrial DNA from a piece of bone that is 40,000 years old. Thus, for the first time, we have access to the sequence of an extinct relative. A comparison with modern humans and chimpanzees showed that Neanderthals were genetically distinct.

Neanderthal genome sequencing

Since the analysis of the small mitochondrial genome provided only limited information, Piabo now took on the enormous task of sequencing the Neanderthal nuclear genome. At this time he was invited to found the Max Planck Institute in Leipzig, Germany. At the new institute, Piabo and his team have been constantly improving methods for extracting and analyzing DNA from archaic bone remains. The research team used new technical developments that made DNA sequencing very efficient. Pääbo has also attracted several important collaborators with expertise in population genetics and advanced sequence analysis. His efforts were crowned with success. Pääbo did the seemingly impossible and was able to publish the first Neanderthal genome sequence in 2010. Comparative analysis showed that the last common ancestor of Neanderthals and Homo sapiens lived about 800,000 years ago.

Piabo and his collaborators could now investigate the relationship between Neanderthals and modern humans from different parts of the world. The comparative analysis showed that Neanderthal DNA sequences were more similar to those of modern humans originating from Europe or Asia than to modern humans originating from Africa. This means that Neanderthals and Homo sapiens interbred during millennia of coexistence. In modern humans of European or Asian descent, approximately 1-4% of the genome is derived from Neanderthals (Figure 2).

Sensational discovery: Denisova

In 2008, a 40,000-year-old fragment of a finger bone was found in Denisova Cave in southern Siberia. The bone contained exceptionally well-preserved DNA, which Pääbo’s team sequenced. The results caused a sensation: the DNA sequence was unique compared to all known sequences of Neanderthals and modern humans. Pyabo discovered a previously unknown hominin, who was named Denisov. Comparison with the sequences of modern humans from different parts of the world showed that gene flow also occurred between Denisova and Homo sapiens. This link was first seen in populations from Melanesia and other parts of Southeast Asia, where individuals carry up to 6% Denisovan DNA.

Piabo’s discoveries have given rise to a new understanding of our evolutionary history. At the time when intelligent man migrated out of Africa, at least two extinct hominin populations inhabited Eurasia. Neanderthals lived in the west of Eurasia, while Denisovans inhabited the eastern parts of the continent. During the expansion of Homo sapiens out of Africa and their migration to the east, they not only encountered and interbred with Neanderthals, but also with Denisovans (Figure 3).

Paleogenomics and its significance

With his pioneering research, Svante Piabo founded a completely new scientific discipline – paleogenomics. After the first discoveries, his group completed the analysis of several additional genome sequences of extinct hominins. Piabo’s discoveries have created a unique resource that is widely used by the scientific community to better understand human evolution and migration. Powerful new sequence analysis techniques show that archaic hominins may have also interbred with Homo sapiens in Africa. However, the genomes of extinct hominins in Africa have not yet been sequenced due to accelerated degradation of archaic DNA in tropical climates.

Thanks to Svante Piabo’s discoveries, we now understand that the archaic gene sequences of our extinct relatives influence modern human physiology. One such example is the Denisovan version of the EPAS1 gene, which confers an advantage for survival at high altitude and is common among modern Tibetans. Other examples are Neanderthal genes that affect our immune response to various types of infections.

What makes us unique people?

Homo sapiens is characterized by its unique ability to create complex cultures, advanced innovations, and visual arts, as well as its ability to cross open water and spread to all parts of our planet (Figure 4). Neanderthals also lived in groups and had large brains (Figure 4). They also used tools, but they evolved very little over hundreds of thousands of years. The genetic differences between Homo sapiens and our closest extinct relatives were unknown until they were identified in Piabo’s seminal work. Intensive ongoing research is focused on analyzing the functional implications of these differences with the ultimate goal of explaining what makes us uniquely human.

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