For example, in 2020 Pääbo and Hugo Zeberg found that the presence of a certain Neanderthal gene variant can double the risk of dying from Covid-19. This gene is present in about 50% of people in South Asia and about 16% of Europeans. They later found another Neanderthal gene variant with possible protective effects against Covid-19. It shows up in about half of people outside of Africa.
Pääbo’s work on Neanderthal DNA has led to a whole new field of studying ancient DNA, and in 2010 brought the world a shocking discovery that went against what every schoolchild knew about Neanderthals being a dead end of the family tree. Neanderthals were our ancestors’ lovers or spouses, or perhaps victims of rape. One way or another, they interbred over thousands of years and passed down their genes to the humans of today.
This genetic heritage has influenced modern people’s risk of type 2 diabetes, Crohn’s disease, lupus, and even smoking behavior. What might seem like an oddity has opened a new window into human physiology and health.
“Some of the most fundamental and deepest questions about human biology can be answered directly from this information from Neanderthals,” said Richard E. Green, a biomolecular engineer who worked with Pääbo to decode the genome from ancient bones.
Some of the Neanderthal genes that humans continue to carry have negative effects on health, others positive effects – or a combination, the overall balance of which depends on environmental factors, e.g. B. which diseases pose the greatest threat. An archaic gene helped Tibetans adapt to life at high altitude.
Recent work by geneticist David Reich at Harvard used bones from ancient humans in our lineage to show that they carried many more genes from the Neanderthal crossbreed than modern humans, suggesting that many of those genes had a deleterious effect. Of the remaining genes, scientists are still sorting out how they affect skin, hair, and susceptibility to disease.
“This crossing was a profound experiment in nature,” said Reich. “The legacy of this mixture lives on in humans today — it injected modern human populations with vast amounts of genetic material that wasn’t there before.”
Pääbo’s lab is now conducting exciting research on the genes that differentiate our brains from Neanderthals — and from every other species on Earth, said Mary-Claire King, a genetics professor at the University of Washington. She is best known for discovering the first breast cancer gene and for her discovery in 1975 that human and chimpanzee DNA is 99% identical.
Comparing our DNA to that of other species has helped us understand what the different human genes do. With Pääbo’s work, she said, we have another, much closer species to reference. Modern humans split from the ancestors of chimpanzees about 7 million years ago and from the ancestors of Neanderthals about 400,000 years ago. We and Neanderthals are 99.8% genetically identical through our common ancestry and through interbreeding that began about 60,000 years ago.
King told me that discovering what is unique about the genes that control brain structure and development in modern humans could shed light on the roots of brain disorders and mental illness – a mystery she is currently working to solve. And it might help us understand why the human mind is so creative and good at problem solving.
Pääbo’s work has uncovered more than just Neanderthal genes — it has uncovered ways to extract DNA from other ancient remains. When I was writing about evolution in the early 2000s, scientists were intrigued by his quest to sequence Neanderthal DNA, but thought that after tens of thousands of years, this delicate molecule would be too degraded to provide much information.
Green said Pääbo is one of the few scientists willing to take a massive risk by embarking on a project that was very likely to fail. “He envisioned technologies that hadn’t yet been invented that could overcome his limitations,” Green said. People advised Green as a young researcher to stay away from ancient DNA, saying such work would get nowhere.
Because Pääbo persisted, we now also know of a previously unknown branch of the human family, the Denisovans. Pääbo discovered our new relatives after sequencing DNA from a finger bone found in Siberia.
Harvard’s empire said it’s now clear that all humans on Earth are intermingled with various archaic species – the Neanderthals, the Denisovans, and in Africa with groups whose bones aren’t fossilized but whose genes have left their mark. We have a different understanding of our past than we did a decade ago, and the implications are only just beginning to be understood.
“These are really early days and I think it will take another decade to really figure out the full extent of the Neanderthal legacy in human genetics,” Green said. It may not sound like typical biomedical research, but the recognition the Nobel Prize brings to this field is well deserved.
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This column does not necessarily represent the opinion of the editors or of Bloomberg LP and its owners.
Faye Flam is a Bloomberg Opinion columnist covering science. She is the moderator of the podcast “Follow the Science”.
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