Swedish Geneticist Bags Nobel Prize for Decoding Ancient DNA

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  • Svante Pääbo has been awarded a Nobel prize for discoveries about the genomes of extinct hominins and human evolution.
  • His work helped to spawn the competitive field of palaeogenomics.
  • He harnessed precious snippets of DNA found in fossils that are tens of thousands of years old.

The work of Svante Pääbo, a geneticist at the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) in Leipzig, Germany, led to the sequencing of the Neanderthal genome and the discovery of a new group of hominins called the Denisovans, and also spawned the fiercely competitive field of palaeogenomics. By tracing how genes flowed between ancient hominin populations, researchers have been able to trace these groups’ migrations, as well as the origins of some aspects of modern human physiology.

A Seminal Contribution

Pääbo’s Nobel win “is an extraordinary recognition of this field maturing and of what he did in putting together everything that needed to be done to accomplish this miracle, which is getting ancient DNA from human remains” says David Reich, a population geneticist at Harvard Medical School in Boston, Massachusetts, who worked closely with Pääbo on the Neanderthal genome sequence. Chris Stringer, a palaeoanthropologist at the Natural History Museum in London, says that Pääbo’s work — including recovery of the oldest ancient human DNA on record, 430,000-year-old sequences from Spain has revolutionized our understanding of the past. “It’s central to human evolutionary studies now” Stringer says, adding that the Nobel win is “great news”.

Studying Damaged DNA

Pääbo had to develop ways of analyzing DNA that had been damaged by thousands of years of exposure to the elements, and contaminated with sequences from microorganisms and modern humans. He and his collaborators then put these techniques to work sequencing the Neanderthal genome, which was published in 2010. This genetic analysis led to the finding that Neanderthals and Homo sapiens interbred, and that 1–4% of the genome of modern humans of European or Asian descent can be traced back to the Neanderthals. Pääbo’s techniques were also used to identify the origins of a 40,000-year-old finger bone found in a southern Siberian cave in 2008. DNA isolated from the bone indicated that it was from neither Neanderthals or Homo sapiens, but came from an individual belonging to a new group of hominins. During the early years of ancient DNA research — led by Pääbo and other scientists in the 1980s and 1990s — the field was plagued by concerns over contamination from modern human DNA. But, thanks to methods developed in Pääbo’s laboratory, as well as the advent of new sequencing technologies, contamination is no longer the ‘bogeyman’ it once was.

Ramification on Health

Pääbo’s work teasing out DNA from Neanderthals, Denisovans and other hominins also has important implications for modern medicine. Although the proportion of the human genome composed of archaic DNA is small, this material seems to punch above its weight, making an important contribution to the risks of diseases ranging from schizophrenia to severe COVID-19. And people living on the Tibetan Plateau can thank Denisovans for gene variants linked to high-altitude adaptation. With genomes from multiple Neanderthals and Denisovans available, it is now possible to identify uniquely human genes, says Johannes Krause, a palaeo geneticist at MPI-EVA. In September, researchers showed that a gene variant found in humans, but not in Neanderthals or Denisovans, is linked to greater neuronal growth in lab-grown brain organoids. “We’ve never come so close to understanding what makes humans humans” Krause says.

Viviane Slon, a palaeo geneticist at Tel Aviv University in Israel who did her PhD under Pääbo’s supervision, says her former mentor has an “uncanny” ability to see the larger picture while remaining laser-focused on details. When Slon was working on remains that turned out to be a first-generation Denisovan–Neanderthal hybrid, the sequence of maternally inherited mitochondrial DNA matched that of a Neanderthal. Pääbo’s influence on ancient DNA work has been such that it’s hard to imagine where the field would be without him. “He’s the godfather of the field” says Skoglund.

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Source: Nature

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