Context:
Recently, the 2022 Nobel Prize for Physiology or Medicine has been awarded to Swedish geneticist Svante Pääbo for his research in the field of genomes of extinct hominins and human evolution.
Relevance:
GS III: Science and Technology
Dimensions of the Article:
- Key Highlights of Svante Paabo’s Research
- Relation between evolution and biology
- Challenges in carrying out such research
Key Highlights of Svante Paabo’s Research
- 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.
- Hominins refer to the now-extinct species of apes that are believed to be related to modern humans, as well as modern humans themselves.
- He 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.
Relation between evolution and biology
- Svante Pääbo established an entirely new scientific discipline, called paleogenomics, that focuses on studying the DNA and genetic information of extinct hominins through reconstruction,
- His discoveries have established a unique resource, which is utilized extensively by the scientific community to better understand human evolution and migration.
Example:
- 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.
Neanderthals
- Neanderthals, the closest relatives of the present-day human species, lived in Europe and West Asia – as far as southern Siberia and the Middle East – before they disappeared around 30,000 years ago.
Denisova
- 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.
Challenges in carrying out such research
- There are “extreme technical challenges because with time DNA becomes chemically modified and degrades into short fragments”.
- 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.
-Source: Indian Express
