Have you ever wondered how far back your family tree reaches? Well, Svante Pääbo the winner of the 2022 Nobel Prize in Physiology or Medicine just added a few thousand years. A Swedish geneticist has been awarded THE NOBEL PRIZE 2022 in PHYSIOLOGY, for his discoveries concerning the genomes of extinct hominins and human evolution.
As human beings, we have always been intrigued about our origin and evolutionary ancestors. Through his meticulous efforts in research, Svante Pääbo has decoded the genomic sequences of Neanderthal, an extinct relative of present-day humans, and previously unknown hominin, Denisova. This ancient flow of genes to present-day humans has physiological relevance today, for example how our immune system reacts to infections. By revealing genetic differences that distinguish Homo sapiens from extinct hominins, his discoveries provide the basis for exploring what makes us uniquely human.
As per the press conference, this discovery was deemed by many as a seemingly impossible task due to 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.
The idea of decoding genomic sequences of ancestors struck him as a postdoctoral student. Pääbo with Allan Wilson, a pioneer in evolutionary biology, started to develop methods to study DNA from Neanderthals, an endeavor that lasted several decades. In 1990, he continued his work on archaic DNA. He decided to analyze 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.
Sequencing the Neanderthal Genome
Pääbo and his team steadily improved the methods to isolate and analyze DNA from archaic bone remains. The research team exploited new technical developments, which made the sequencing of DNA highly efficient. Pääbo also engaged several critical collaborators with expertise in population genetics and advanced sequence analyses. His efforts were successful. Pääbo accomplished the seemingly impossible and went on to publish the first Neanderthal genome sequence in 2010.
A Sensational discovery: Denisova
In 2008, a 40,000-year-old fragment from a finger bone was discovered in the Denisova cave in the southern part of Siberia. The bone contained exceptionally well-preserved DNA, which Pääbo’s team sequenced. The 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 given the name Denisova. Comparisons with sequences from contemporary humans from different parts of the world showed that gene flow had also occurred between Denisova and Homo sapiens.
Conclusion
Pääbo’s discoveries have generated a new understanding of our evolutionary history. At the time when Homo sapiens migrated out of Africa, at least two extinct hominin populations inhabited Eurasia. Neanderthals lived in Western Eurasia, whereas Denisovans populated the eastern parts of the continent. During the expansion of Homo sapiens outside Africa and their migration east, they encountered and interbred with Neanderthals and Denisovans.
What made us stand out?
This is a common question that pops into our minds while reading the article. Homo sapiens is characterized by its unique capacity to create complex cultures, advanced innovations and figurative art, as well as by the ability to cross open water and spread to all parts of our planet. Neanderthals, also had big brains and had developed tools for their livelihood but these tools were not developed intensively during their hundreds of thousands of years.
Did you miss the news about the Nobel Prize 2022 in Physics? Read here: 2022 Nobel Prize In Physics Shared By Trio For The Breakthroughs In Quantum Science
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