Researcher who sequenced Neanderthal genome awarded Nobel Prize

Research that has helped us to understand our ancient ancestors has been recognised with a Nobel Prize.

The 2022 Nobel Prize for Physiology or Medicine has been awarded to Professor Svante Pääbo for 'his discoveries concerning the genomes of extinct hominins and human evolution'.

These include deciphering some of the earliest genetic sequences of Neanderthals, as well as identifying a little-known group of hominins known as the Denisovans, who are known to have lived between 200,000 and 45,000 years ago.

His citation by the Nobel Assembly adds, 'Through his groundbreaking discoveries, Pääbo opened a new window to our evolutionary past, revealing an unexpected complexity in the evolution and admixture of ancient hominins, as well as providing the basis for an improved understanding of genetic features that make us uniquely human.'

Professor Ian Barnes, an expert in ancient DNA (aDNA) at the Museum, says, 'I'm delighted to see that Svante's work has been recognised by the Nobel Committee.'

'In essence, he created the field that we’re lucky enough to work in, and he and his team have been at the forefront of technical development and innovation for over 30 years.'

Who is Svante Pääbo?

Svante Pääbo was born in Stockholm, Sweden, in 1955. He is the son of Sune Bergström, a biochemist who won the 1982 Nobel Prize for Physiology or Medicine for his work investigating a group of compounds known as prostaglandins.

During the course of his PhD, Pääbo showed that DNA could survive in the mummies of ancient Egyptians, something that set the scene for his later work. Alongside other scientists, he began developing new techniques to study the aDNA of extinct human species.

His work allowed scientists to answer complex questions about our origins, which until that point had relied mainly on fossils.

Professor Chris Stringer, a human evolution expert at the Museum, says, 'The use of aDNA made a huge contribution to the study of human evolution.'

'At the time, there were numerous debates, such as whether our species, Homo sapiens, evolved from Neanderthals. There was no easy way to resolve these disagreements from fossils, as interpretations of similar features could vary significantly.'

There had been some attempts at reconstructing the DNA of our ancestors from our own genome, which in 1987 led to the announcement of mitochondrial Eve, the most recent mitochondrial ancestor of all living humans.

However, these investigations did not shed light on non-human hominins. Pääbo and his colleagues developed new techniques to help extract aDNA from ancient specimens, and remove contamination accumulated across thousands of years.

In the 1990s, this led to the first sequencing of the mitochondrial genome of Neanderthals, which revolutionised our understanding of these hominins.

'Until 40 years ago, it was thought that Neanderthals were a subspecies of Homo sapiens, and not their own species,' Chris explains. 'Work I was involved in during the 1970s and 1980s moved the Neanderthals further away from us and asserted that they could be a different species, which Pääbo's research affirmed.'

After sequencing the mitochondrial DNA, which is contained within small, self-replicating organelles in animal cells, Pääbo turned his attention to the nuclear genome, which encodes the instructions for how an organism develops and grows.

In 2010, this led to the first high-quality transcription of a complete Neanderthal genome, which revealed that while they are a distinct species of humans, many of us share around 2% of their DNA. Some of this DNA may be active in our bodies, something that is a developing area of medical research.

Since then, further genomes have been documented, with Pääbo collaborating with Museum scientists in 2019 to examine Neanderthal skulls held in the Museum collection.

Dr Selina Brace, one of the Museum scientists who co-authored this paper, says, 'We've been fortunate enough to work with Svante Pääbo and the Leipzig ancient DNA group that he leads on many occasions.

'The work they've done establishing the genetic basis of how we differ to our closest, extinct relatives is incredible, and continues to show how the past is so important in explaining the present.'

Discovering the Denisovans

In 2010, Pääbo was one of the authors of papers revealing the mitochondrial, and subsequently complete, genome of an unknown species of human extracted from a bone preserved in a Siberian cave.

The way this species, known as the Denisovans, was revealed is very different from previous discoveries of human species. Instead of being identified through its fossils, which are scarce and fragmentary, the DNA has led the way on studying these hominins.

'Denisova cave, where the species was discovered, continues to be a hotbed of research activity,' Chris says. 'It's not only allowing high quality Denisovan genomes to be extracted from bone fragments but revealing a Denisovan/Neanderthal hybrid.'

'There's also research taking place on the sediments of the cave, allowing us to get DNA from about 200,000 years ago when fossils aren't even present.'

The study of aDNA is only set to continue expanding, with research used to understand not only our evolution, but also historic population changes and even medieval crimes.

Pääbo and his team continue to work on new ways of analysing aDNA fragments, including even smaller samples and those which are more degraded. In future, they hope to study DNA from further back in time, giving deeper insight into the origins of humans.