How to distinguish a good scientist: Look to Svante Pääbo
Several sources in the media have been announcing the winners of this year’s prestigious Nobel Prize in scientific fields, an international award overseen by the Nobel Foundation in Stockholm, Sweden, and based on the fortune of Alfred Nobel, Swedish inventor and entrepreneur.
Many who dedicate their lives and careers to science have dreamed of becoming a Nobel laureate, but it only happens to those who inarguably demonstrate a true understanding of the field and its highest aspirations.
The winner of the 2022 Nobel Prize in Medicine or Physiology is Svante Pääbo, a Swedish geneticist who is credited with founding an important new field of study, paleogenetics, and making major contributions to the fields of evolution, genetics, and current clinical medicine (including what DNA tells us about who has a higher risk of contracting severe Covid-19).
He received the honor “for his discoveries concerning the genomes of extinct hominins and human evolution.” According to the Nobel Prize website:
Through his pioneering research, Svante Pääbo accomplished something seemingly impossible: sequencing the genome of the Neanderthal, an extinct relative of present-day humans. He also made the sensational discovery of a previously unknown hominin, Denisova. Importantly, Pääbo 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.
Pääbo studies ancient DNA samples found in bones and other remains in caves where other ancient artifacts have been found. While his amazing discoveries and substantial career of hard work attests to why he was selected for the prize, what also struck me is his character, and how he embodies the principles of sound science and best practices for exploring the world around us.
I have divided these admirable traits into five areas (although I am sure others would add more):
1) Dedication to using the best methods available, and in cases where techniques currently fall short, working tirelessly to improve them
When Pääbo began his work, during the early years of ancient DNA research, the field worried about deterioration and contamination. Almost everyone thought this challenge could not be overcome, and the world would never be able to identify DNA sequences from ancient artifacts.
According to an article in Nature following the announcement of Pääbo’s win:
Pääbo had to develop ways of analysing 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…
… [T]hanks 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. “When I started, we weren’t even sure you could work with ancient human DNA,” says Pontus Skoglund, a palaeogeneticst at the Francis Crick Institute in London. “But now, and I think led by Svante’s department, we have an approach where contamination is really not a major issue anymore.”
This work on improving analysis techniques led to several monumental discoveries by Pääbo and others, including the identification of a new type of hominem (known as Denisovan) from 40,000-year-old remains found in a Russian cave, that was different from both humans and Neanderthals. Denisovan DNA has been found in billions of today’s humans living throughout the world.
2) Admitting to an investigation’s failure and being open about why it failed
According to the same article in Nature, Pääbo has been very forthcoming that his original analysis on DNA from ancient Egyptian mummy remains was likely unwittingly carried out on his own DNA.
3) Waiting for replication of findings, and being open to doubting conclusions, while continuing to investigate, before claiming a discovery
Dr. David Reich, a geneticist at Harvard, worked with Pääbo and others on an investigation that found humans and Neanderthals had mixed. According to the Washington Post:
[Reich] said that when he joined the project, he — like many in the field — expected not to find evidence of mixing between Neanderthals and humans. ‘When we saw the first evidence that it had occurred … it was surprising and unexpected, and I thought it was likely to be an error of our analysis — and I spent a lot of time trying to make it go away,’ Reich said.
Under Pääbo’s leadership, the work continued. Members of the project replicated the results and combined them with other multiple lines of evidence to support the conclusion.
4) Dedication to mentorship and playing the long game
According to Nature, “Researchers describe Pääbo as intense and driven, but also collegial and generous. His department at the Max Planck Institute for Evolutionary Anthropology has produced a generation of palaeogeneticists who are pushing the field ever further.”
One of his Ph.D. students remembers how after she thought she had discovered the DNA she was working with was that of a Neanderthal, Pääbo urged her not to publish until they had sequenced the DNA from both parents. It ultimately turned out to be the DNA of a Denisovan-Neanderthal, a significantly more far-reaching discovery.
“He wouldn’t let me write that it’s a Neanderthal because we didn’t know that, and in fact it turned out to be a mixed offspring,” she remembered. This is a great example of how science lives on, and moves forward, when experienced scientists spend time mentoring students with promise to move beyond their current limitations.
Several reports claim that when the head of the Nobel Committee called Pääbo, he thought it was his colleagues playing a joke. Even when he saw the call coming from Sweden, he believed it might be about a small home he still owns there. “What really drives our work is really curiosity,” he told the New York Times. “It is just as if you do an archaeological investigation to find out about the past. We sort of make excavations in the human genome.”
Using the past to guide the future
It is fortunate the Nobel committee and others are recognizing the significance of this work, as well as the character of the man who led it.
As a former Ph.D. student, now colleague, described Pääbo’s work:
The ancient genomes “allow us to understand what makes humans humans.”
… Comparing modern and extinct human lineages has given scientists new insights into brain development, autism, nicotine addiction, and the immune system’s response to COVID-19 and other diseases, he notes.
These discoveries also help the world understand that humans are not a collection of “pure” species or races. As David Reich explained to the Washington Post, “It’s changed our biology and the history of everybody. We all know we are all mixed.”
The career of Svante Pääbo shows us that strong science, performed with dedication, transparency, skepticism, and humility, leads to a better world for us all.