2022 Nobel Prize in Medicine goes to research on human evolution

The 2022 Nobel Prize in Physiology or Medicine goes to Swedish researcher Svante Pääbo, 67, laureate for unraveling the genomes of extinct hominins, that is, missing members of the primate group to which humans belong. Among other accomplishments, in 2010 he coordinated work that sequenced (“spelled”) the complete DNA of Neanderthals, who disappeared about 40,000 years ago.

Pääbo alone will receive the award of 10 million Swedish kronor (just over US$ 900 thousand, or R$ 4.8 million, at the September 30 price). In addition, he will be awarded a diploma and a medal.

Born in Stockholm, Pääbo has worked for decades at the Max Planck Institute for Evolutionary Anthropology in Leipizig (Germany). With pioneering work dating back to the 1980s, he was one of the first to demonstrate that it was possible to obtain genetic material from humans who died thousands of years ago.

Pääbo’s first studies were of Egyptian mummies, a reflection of his initial dream of working as a scholar of ancient Egypt, but his efforts soon turned to more ambitious goals: the archaic relatives of the Homo sapiens.

It so happens that the researcher became a member of this branch of research precisely during the years when the hypothesis known as “out of Africa” ​​was gaining strength. According to her, all people alive today would descend from humans with modern anatomy who would have left Africa and started to populate the other continents between 100,000 and 60,000 years ago.

At that time, there were other hominins living outside Africa, such as Neanderthals (Homo neanderthalensis) in Europe and the Middle East and, perhaps, small populations of the homo erectus in Southeast Asia. According to the “out of Africa” ​​hypothesis, modern humans of African origin would have completely replaced these populations.

These conclusions came from the analysis of ancient skeletons and the DNA of current human populations, but ancient DNA could be the decisive evidence on the topic.

Throughout the 1990s and 2000s, most of the data obtained by Pääbo and his colleagues, such as the German Johannes Krause and the American David Reich, seemed to fully support the “out of Africa” ​​scenario. He and his team were the first to “read” a small snippet of the Neanderthals’ genetic material — mtDNA, or mitochondrial DNA, which is present only in mitochondria, the power plants of cells, and is passed down exclusively through the maternal lineage, from mother to mother. for daughter or son.

Neanderthal mtDNA appeared to be unique to the species and, to date, has not been found in any living person. The simplest interpretation, said Pääbo, is that Neanderthals would not have left any modern descendants, even partially.

Ancient DNA experts, however, continued to refine their techniques, with the Swede always at the forefront. Increasingly rigorous DNA extraction methods (to avoid contamination with modern DNA), more laboratory care and more refined computer analysis of the fingers allowed the expansion of studies to nuclear DNA, that is, the “main” genome, present in the nucleus. of the cells. With that, Pääbo’s team decided to produce a “draft” of the complete genome of Neanderthals (“draft” because the quality of the DNA reading is not as good as that of a person’s genome today).

When the data finally started to fall into place, the team had to change its mind. They detected a small but unmistakable similarity of Neanderthal DNA to that of present-day people of non-African origin — both in Europe and Asia, and also between the indigenous peoples of the Americas and the natives of Oceania.

The most plausible explanation for this was that, upon leaving Africa, the ancestors of non-African peoples interbred with Neanderthals, and this heritage carried over to most of today’s humanity. It is estimated that up to 2% of the genome of these people came from the Homo neanderthalensis.

Later studies confirmed these initial data and indicate that miscegenation happened multiple times in several places in Eurasia. Finally, Pääbo and his collaborators are also responsible for the discovery of the Denisovans, mysterious hominins identified from bone and dental fragments found in the Denisova cave in Siberia.

It is not known exactly what territory they occupied or what they looked like, but the Denisovans were, DNA shows, archaic hominins different from Neanderthals, but who interbred with them and also with Neanderthals. Homo sapiens. Native peoples of Oceania and Southeast Asia, such as Aboriginal Australians, Papuans, and Philippine tribal groups, carry small portions (up to 5%) of Denisovan DNA in their genome.

Pääbo’s works, therefore, ended up showing that the “out of Africa” ​​model, while largely correct, ignored the long interaction and miscegenation of the Homo sapiens Africans with their archaic relatives.

Archaeologist André Strauss, from USP, who coordinates a pioneering laboratory in the analysis of samples of ancient DNA in Brazil, celebrated the award. “The Pääbo award is the consecration of evolutionary anthropology and quantitative approaches as one of the most important ways of studying the human past. For the humanities in Brazil, it should serve as a shining beacon, indicating a valuable path to follow.” , he declared.

family history

Pääbo’s father, biochemist Sune Bergström, also won the Nobel Prize in medicine, sharing the prize with two other winners in 1982. The 2022 winner, however, grew up with his mother, Estonian-born chemist Karin Pääbo.

The Swedish researcher is bisexual and mainly dated men before marrying American primatologist and geneticist Linda Vigilant. They have two children. Pääbo recounts a good part of his personal and scientific trajectory in the book “Neanderthal Man: In Search of Lost Genomes”, still unpublished in Brazil.

previous awards

In 2021, the laurel went to the American David Julius, 65, and the Lebanese of Armenian origin, Ardem Patapoutian, 54. The two elucidated the mechanisms that allow the nervous system to capture temperature stimuli and touch the skin.

In 2020, the Nobel Prize in Medicine was shared by three researchers for the discovery of the hepatitis C virus. The American Harvey Alter, from the US National Institutes of Health (NIH), the British Michael Houghton, from the University of Alberta, and also the American Charles Rice of Rockefeller University were the laureates.

Because of the pandemic, in 2020 and 2021, medals and award diplomas were sent to the winners’ homes.

In 2019, William G. Kaelin, from Harvard University, Peter J. Ratcliffe, from the University of Oxford, and Gregg L. Semenza, from Johns Hopkins University, were awarded for research on how cells perceive and change behavior according to with the availability of oxygen.

In 2018, it was the turn of James P. Allison and Tasuku Honjo to be laureates for discoveries related to immunotherapy, that is, the fight against cancer with drugs that enhance the function of the immune system.

Among the award-winning discoveries in the past are those of the structure of DNA by James Watson, Francis Crick and Maurice Wilkins (1962), that of penicillin by Fleming and others (1945), that of the citric acid cycle by Hans Krebs (1953) and the of the structure of the nervous system by Camillo Golgi and Santiago Ramón y Cajal (1906).

Other notable discoveries awarded by the Nobel Prize in Medicine or Physiology are insulin (1932), the relationship between HPV and cancer (2008), in vitro fertilization (2010), that blood groups exist (1930) and how hormones act (1971).

The only person born in Brazil who received a Nobel was the British Peter Medawar, for his discovery of the basis of acquired immune tolerance, that is, the ability to make an organism’s immune system not react to certain factors.

“It is my wish that, in awarding the prizes, no consideration should be given to nationality, but that the prize should be given to the most worthy person, whether Scandinavian or not,” reads Alfred Nobel’s will.

Despite the desire, the concentration of scientific awards in rich countries is expressive. Not to mention the small number of women awarded, only 12 out of 222 laureates – and the Nobel Prize in Medicine, among the scientific prizes, is still the one with the highest female participation.

How the Nobel Prize Winner is Chosen

The traditional Nobel Prize began, in a way, with the death of Alfred Nobel, inventor of dynamite. In 1895, in his last will, Nobel recorded that his fortune should be used for the construction of a prize – which was received by his family with dispute. The first prize was given in 1901.

The choice of the winner of the main prize in the field of physiology or medicine starts with nominations from a group of 50 researchers linked to the Karolinska Institute, in Sweden. Alfred Nobel, in his will, assigned to the institution the mission of electing to receive the laurel the one who has made notable contributions to the future of humanity.

The process begins in the year prior to the award, more specifically in September, with the sending of invitations to indicate a name for the award, which must occur until January 31st.

Members of the Nobel Committee of the Karolinska Institute can nominate; professionals in the field of biology and medicine linked to the Royal Swedish Academy of Sciences; winners of physiology or medicine or chemistry prizes; full professors of medicine from Swedish, Norwegian, Finnish, Icelandic or Danish institutions; professors in similar positions in other medical faculties of universities around the world, selected by the Nobel Committee, with the aim of ensuring the proper distribution of the task among several countries; and academics and scientists selected by the Nobel Committee.

Self-appointments are not accepted.