Science Tuesday - Archaeology and Neanderthals,
A Sunken Kingdom Re-emerges
By Katrin Bennhold, The New York Times, June 23, 2014
BORTH, WALES - There is a poem children in Wales learn about the sunken kingdom of Cantre’r Gwaelod, swallowed by the sea and drowned forever after. On a quiet night, legend has it, one can hear the kingdom’s church bells ringing.
When the sea swallowed part of Britain’s western coastline this year and then spat it out again, leaving homes and livelihoods destroyed but also a dense forest of prehistoric tree stumps more exposed than ever, it was as if one had caught a faint glimpse of that Welsh Atlantis.
The submerged forest of Borth is not new. First flooded some 5,000 years ago by rising sea levels after the last ice age, it has been there as long as locals remember, coming and going with the tides and occasionally disappearing under the sand for years on end. But the floods and storms that battered Britain earlier this year radically changed the way archaeologists interpret the landscape: A quarter-mile-long saltwater channel cutting through the trees, revealed by erosion for the first time, provided a trove of clues to where human life may have been concentrated and where its traces may yet be found.
Ancient animal footprints on a beach near Borth, Wales. Archaeologists have had to race against time to study and preserve such remains before the sea further eroded them.
“We used to think of this as just as an impenetrable forest - actually this was a complex human environment,” said Martin Bates, a geoarchaeologist at the University of Wales Trinity St. David, who oversees the excavation work in Borth on a beach he played on as a toddler. “The floods have opened our eyes as to what’s really out there.”
Scanning the army of ghostly spikes protruding from the sand here one recent morning, Dr. Bates said it was as if nature were making a point: The recent torrential rains, linked by a growing number of climatologists to human-induced climate change, have provided an ancient laboratory to study how humans coped with catastrophic climate change in the past.
Indeed, across Britain, two consecutive years of exceptional winter weather have left in their wake some equally exceptional discoveries: from unexploded wartime bombs and Victorian shipwrecks to archaeological finds that are nearly a million years old. Scientists have barely kept up. Last winter was the wettest on record, according to the Met Office, the national weather service.
Dog walkers and amateur archaeologists are being sought in ever-greater numbers to help record new sites. In some areas hit especially hard by erosion, locals are equipped with cameras that log digital images with geocoordinates so the artifacts they find on beach walks can be added to national databases.
“Archaeologists can’t be everywhere, but locals can,” said Erin Kavanagh, Dr. Bates’s partner and a fellow archaeologist.
Nicholas Ashton, the curator of Paleolithic and Mesolithic collections at the British Museum, has been organizing “fossil road shows” in which he invites civilians to bring in any potential archaeological finds and have them identified. (One man recently showed up with a six-inch-long hippo tusk and a well-preserved ax, both found locally and both more than half a million years old.)
Having those extra eyes on the ground can make all the difference in coastal areas, Dr. Ashton said, for what the sea reveals, it tends to reclaim almost as soon. He learned this lesson firsthand.
In May 2013, shortly after the first set of storms, Dr. Ashton commissioned Dr. Bates, an old university friend, to work on Britain’s east coast in Norfolk. The beach near Happisburgh (pronounced hays-boro), a longstanding archaeological site, had suffered severe erosion. Dr. Ashton, an expert in early humans, wanted a geophysical survey to map any channels or rivers that might lie beneath about 30 feet of sediment. Some of these channels, he reckoned, might contain evidence of early humans because sources of freshwater would have been natural gathering spots.
It was on their second visit, on May 10, that Dr. Bates noticed some indentions on the otherwise flat horizons of the laminated silts recently laid bare on the beach. The humps and bumps looked familiar. He told Dr. Ashton: “They’re just like the human footprints in Borth.”
Footprints of humans and animals in Borth had been dated to about 6,000 years ago. The site in Happisburgh was 900,000 years old, a time when mammoths and hippos still roamed in these parts. No human bones or prints that old had ever been found in Britain.
Could this be possible?
A frantic race against time began. Every day, the shape of the prints would blur a little more as the coming tide eroded the contours of heels, toes and arches. A team led by Sarah Duffy from the University of York arrived to apply a technique called multi-image photogrammetry, taking about 150 digital photographs of the surface area containing the prints and feeding it into a program that created a three-dimensional model. By the time another team had come to do some laser scanning, it was too late: The prints were barely visible.
Panicked, scientists lifted from the site a 130-pound block of sediment with one faint print on top, to have it analyzed at the National Oceanography Center. It is the only remaining physical evidence of the footprints: Before the month was out, all traces of them had vanished. It was a powerful reminder of both the resilience and the fragility of human life.
“What had been preserved for nearly one million years was taken back by the sea in the space of 10 days,” Dr. Ashton said.
Initially skeptical, he said he knew the footprints were real when Dr. Duffy’s computer images landed in his inbox sometime last June. “I thought, bloody hell, we are dealing with something quite extraordinary here,” he said.
The footprints, the oldest known outside Africa, probably belonged to a family group of Homo antecessor, a cousin of Homo erectus that possibly became extinct when Homo heidelbergensis from Africa settled in Britain about 500,000 years ago, he said. Using foot-length-to-stature ratios, scientists estimate that the male was perhaps 5 feet 9 inches tall, and the smallest child a little less than 37 inches.
Little is known about this early human species. Fossil skeletons in Atapuerca, Spain, from around the same time suggest that they walked upright and looked much like modern humans, though their brains were smaller. If they had language, it was primitive. Living at the tail end of an interglacial era, as winters were growing colder, they may have had functional body hair. So far, there is no evidence that they used clothes, shelter, fire or tools more complex than simple stone flakes.
But despite their elusiveness, the human ancestors in whose footsteps modern-day Britons walk - literally - have fascinated the nation. Before some basic tools were found here in 2010, it had been believed that humans had entered Britain much later, about 700,000 years ago, Dr. Ashton said. (Before 2005, when another set of tools was discovered in Suffolk, the presumed date was 500,000 years ago.)
“British civilization started in Norfolk,” a headline in The Times of London put it at the time. A blog post by Dr. Ashton on the British Museum website on Feb. 7, when the paper he co-wrote about the footprints appeared, had more hits than any other post on the museum’s site before or since.
“We can reconstruct the climate and climate change nearly one million years ago,” Dr. Ashton said. “The big lesson is, we have to adapt. Whether we like it or not, the climate will change - it always has - and today we are accelerating that change.”
Standing on the ridge above Cardigan Bay in Borth, Dr. Bates described what the area would have looked like at the height of the last ice age some 20,000 years ago: more than half a mile of ice overhead and dry land stretching across today’s North Sea. The sea level was 400 feet lower than it is today.
“You could have walked from Denmark to Yorkshire in those days,” he said.
About 10,000 years ago, temperatures warmed sharply, by eight to 10 degrees Fahrenheit. By that time, the European ice sheets had melted, but the much thicker North American sheets took much longer. While the climate had warmed to today’s levels, allowing mixed oak woodland to grow and humans to recolonize Britain, the sea level remained some 130 feet lower for another 3,000 years.
When it did rise, it would have been traumatic for the population, wiping out whatever settlement there was, and eventually the forest of Borth. The displaced humans of the time, Dr. Bates said, were prehistoric refugees from climate change.
“Even in the reduced life span of the day, the coastline would have advanced dramatically,” said Dr. Bates, who is convinced that stories like Cantre’r Gwaelod originated in this period.
Similar tales abound on the western European seaboard: There are Cornish and Breton versions, and variations of the theme exist in Jersey and the Orkney Islands. The ultimate legend, of course, is Atlantis, which Plato placed somewhere in the North Atlantic.
“It was a traumatic geological event, and people turned it into a story to make sense of it,” said Gerald Morgan, a retired head teacher and local historian in nearby Aberystwyth.
The same thing is happening again today, as Britons survey the damage of the past couple of years of flooding and storms and ponder the future. The submerged forest in Borth, little known outside a small radius here, has once again become part of local lore. Its haunting shapes are featured in poetry slams and in storytelling evenings, and modern-day performances of Cantre’r Gwaelod have been staged on the beach, said Mr. Morgan and his wife, Enid.
Have they ever heard the bells?
Mrs. Morgan smiled. “I knew someone who did.”
Searching for Answers in Very Old DNA
By Caludia Dreifus, The New York Times, June 23, 2014
As he puts it in the subtitle of his memoir, “Neanderthal Man,” Svante Paabo goes in search of lost genomes. Dr. Paabo, a 59-year-old Swede who leads his own laboratory at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, was the first to extract and sequence the genomes of the ancient humans called Neanderthals and Denisovans, and to compare them with those of modern humans. Genes, and the stories they tell, are texts he reads.
We recently spoke for three hours in Washington, and later on the telephone. Here is an edited and condensed version of our conversation.
Q. DID YOU ALWAYS WANT TO BE A GENETICIST?
A. I wouldn’t say so. When I was 13, my mother took me to Egypt. That made a big impression; afterward I thought I might become an Egyptian archaeologist. I had a very romantic idea what that would be
like: discovering mummies and pyramids and things like that. I even started studying Egyptology at the university. But there, my romantic ideas caught up with reality. In the 1970s, Swedish Egyptology was very linguistically oriented. It was about ancient word forms and translating hieroglyphics. I couldn’t imagine spending my life with it.
Q. HOW DID YOU COME TO INVENT AN ENTIRELY NEW RESEARCH AREA, THE GENETICS OF ANCIENT HUMANS?
A. In the late 1970s, while I was doing my medical studies [at Uppsala University in Sweden], these new techniques for studying DNA wereintroduced - cloning, sequencing. I was amazed by them and learned how to do them.
And that brought me to thinking again about Egyptian antiquities. I knew that there are hundreds of mummies stored in museums across Europe. Mummies, after all, are the dried-out bodies of dead people or animals. I wondered if in some, their DNA might still be preserved. If it was present, we could study it just as we study the DNA of people alive today.
My thought was, “If we could do this, we can answer many questions in history that we cannot otherwise answer.”
Q. SUCH AS?
A.Are the people who built the pyramids the direct ancestors of the people who live in Egypt today? Or: When the Neanderthals encountered modern humans, did they mix?
But to do this, one needed to obtain DNA that might be preserved in those ancient human remains. In the 1970s, many people thought that DNA was so sensitive a molecule that it probably degraded within hours of death. I thought I should test that idea. So I bought a piece of calf’s liver and dried it in an oven. The DNA survived!
Encouraged, I went on to test for DNA in some Egyptian mummies kept in our small museum in Uppsala. However, I couldn’t find any DNA in a single one. Eventually, my Egyptology professor, who had some
contacts in what was then East Germany, arranged for me to go to the Bode Museum to collect samples from their large collection of mummies.
Back in Uppsala, I studied the samples from the Bode mummies under a microscope, always searching for the remains of a cell nucleus. This is a part of the cell where the genome is located. After a few weeks, I detected a cell nucleus that appeared to contain preserved DNA. This was so encouraging.
Q. IN 2010 YOUR RESEARCH GROUP SEQUENCED THE NEANDERTHAL’S GENOME. DID IT SHOW THAT THE GROUPS HAD MIXED?
A. When we compared the Neanderthal genome to the genes of today’s humans, it showed they had. If your ancestry is from Europe or Asia, 1 to 2 percent of your DNA comes from Neanderthals. Sub-Saharan Africans don’t have Neanderthal genes because the Neanderthals never were there.
Q. YOUR LABORATORY IDENTIFIED A NEW GROUP OF EXTINCT HUMANS. HOW DID YOU COME TO DISCOVER THEM?
A. Some Russian colleagues sent us a tiny little bone fragment they’d found in a southern Siberian cave two years earlier. At first I thought it was a Neanderthal or a modern human. Yet as we began to sequence its DNA, it became clear it was neither.
Soon we saw that the ancestors of this child, a girl, had a common ancestor with Neanderthals. It went back very far, though - at least 200,000 years. We also saw that her group had a long history independent of the Neanderthals. So now it was clear: we were working on the genome of a human group that wasn’t known before.
This was the first time a new form of extinct human had been described from genome sequences and not fossil bones. We named them Denisovans, after the Denisova Cave, where the bone had been found.
As with the Neanderthals, we wondered if the Denisovans had contributed genes to human populations today. It turned out that they had. We found that they contributed DNA to people in the Pacific region -
in New Guinea and some of the islands.
Q. HOW DO YOU THINK THAT HAPPENED?
A. Beyond what the genome says, one can’t know. The easiest explanation is that when modern humans came through South Asia, they encountered Denisovans, bred with them and continued migrating.
Q. WILL THERE BE MORE HUMAN GROUPS DISCOVERED IN THE NEXT FEW YEARS?
A. Had you asked me this before the Denisovans, I would said, “Nah, we pretty much know what’s there.” But now I feel there is a lot more to be discovered. In particular, we need to look more in China. It’s unclear howthe humans who lived in China 50,000 to 100,00 years ago relate to the Denisovans and Neanderthals. So China is a very important place.
But there are interesting things in Europe too. In Spain, there’ve been some very important discoveries with 400,000-year-old Homo heidelbergensis. We are very excited that we’ve been able to get some DNA
from one of the fossils there.
Q. WHEN YOU WERE GROWING UP, DID YOU HAVE A SENSE THAT SCIENCE WOULD BE YOUR FUTURE?
A. Well, science was certainly there in the background in the family. I grew up with my mother, and she was a chemist. My father [the Nobel laureate Sune Bergstrom], he was a biochemist.
My father was someone who showed up on Saturdays and sort of took an interest in my education. He had another family. We were like “the secret family.” So when he got his Nobel Prize, we could watch that on television.
DID THAT TROUBLE YOU?
A. I had known from the time I was the tiniest baby that this is how it works. I never experienced this as a big problem. A lot of kids grow up with single mothers. I was close to my mother.
Q. DID YOUR FATHER LIVE TO SEE YOUR ACCOMPLISHMENTS?
A. He died in 2004. But I think he was proud. He was very distant. I mean, he led this double life. He could not allow himself to become very emotional with me, because where would that leave him?
Q. ON A HAPPIER NOTE, DO YOU EVER REFLECT ON WHAT AN ADVENTURE YOUR CAREER HAS BEEN? YOU GREW UP TO BECOME INDIANA JONES, AFTER ALL.
A. Yes, it has so much exceeded my wildest dreams. Rather than be the archaeologist, I ended up studying history in a new way.
By Katrin Bennhold, The New York Times, June 23, 2014
BORTH, WALES - There is a poem children in Wales learn about the sunken kingdom of Cantre’r Gwaelod, swallowed by the sea and drowned forever after. On a quiet night, legend has it, one can hear the kingdom’s church bells ringing.
When the sea swallowed part of Britain’s western coastline this year and then spat it out again, leaving homes and livelihoods destroyed but also a dense forest of prehistoric tree stumps more exposed than ever, it was as if one had caught a faint glimpse of that Welsh Atlantis.
The submerged forest of Borth is not new. First flooded some 5,000 years ago by rising sea levels after the last ice age, it has been there as long as locals remember, coming and going with the tides and occasionally disappearing under the sand for years on end. But the floods and storms that battered Britain earlier this year radically changed the way archaeologists interpret the landscape: A quarter-mile-long saltwater channel cutting through the trees, revealed by erosion for the first time, provided a trove of clues to where human life may have been concentrated and where its traces may yet be found.
Ancient animal footprints on a beach near Borth, Wales. Archaeologists have had to race against time to study and preserve such remains before the sea further eroded them.
“We used to think of this as just as an impenetrable forest - actually this was a complex human environment,” said Martin Bates, a geoarchaeologist at the University of Wales Trinity St. David, who oversees the excavation work in Borth on a beach he played on as a toddler. “The floods have opened our eyes as to what’s really out there.”
Scanning the army of ghostly spikes protruding from the sand here one recent morning, Dr. Bates said it was as if nature were making a point: The recent torrential rains, linked by a growing number of climatologists to human-induced climate change, have provided an ancient laboratory to study how humans coped with catastrophic climate change in the past.
Indeed, across Britain, two consecutive years of exceptional winter weather have left in their wake some equally exceptional discoveries: from unexploded wartime bombs and Victorian shipwrecks to archaeological finds that are nearly a million years old. Scientists have barely kept up. Last winter was the wettest on record, according to the Met Office, the national weather service.
Dog walkers and amateur archaeologists are being sought in ever-greater numbers to help record new sites. In some areas hit especially hard by erosion, locals are equipped with cameras that log digital images with geocoordinates so the artifacts they find on beach walks can be added to national databases.
“Archaeologists can’t be everywhere, but locals can,” said Erin Kavanagh, Dr. Bates’s partner and a fellow archaeologist.
Nicholas Ashton, the curator of Paleolithic and Mesolithic collections at the British Museum, has been organizing “fossil road shows” in which he invites civilians to bring in any potential archaeological finds and have them identified. (One man recently showed up with a six-inch-long hippo tusk and a well-preserved ax, both found locally and both more than half a million years old.)
Having those extra eyes on the ground can make all the difference in coastal areas, Dr. Ashton said, for what the sea reveals, it tends to reclaim almost as soon. He learned this lesson firsthand.
In May 2013, shortly after the first set of storms, Dr. Ashton commissioned Dr. Bates, an old university friend, to work on Britain’s east coast in Norfolk. The beach near Happisburgh (pronounced hays-boro), a longstanding archaeological site, had suffered severe erosion. Dr. Ashton, an expert in early humans, wanted a geophysical survey to map any channels or rivers that might lie beneath about 30 feet of sediment. Some of these channels, he reckoned, might contain evidence of early humans because sources of freshwater would have been natural gathering spots.
It was on their second visit, on May 10, that Dr. Bates noticed some indentions on the otherwise flat horizons of the laminated silts recently laid bare on the beach. The humps and bumps looked familiar. He told Dr. Ashton: “They’re just like the human footprints in Borth.”
Footprints of humans and animals in Borth had been dated to about 6,000 years ago. The site in Happisburgh was 900,000 years old, a time when mammoths and hippos still roamed in these parts. No human bones or prints that old had ever been found in Britain.
Could this be possible?
A frantic race against time began. Every day, the shape of the prints would blur a little more as the coming tide eroded the contours of heels, toes and arches. A team led by Sarah Duffy from the University of York arrived to apply a technique called multi-image photogrammetry, taking about 150 digital photographs of the surface area containing the prints and feeding it into a program that created a three-dimensional model. By the time another team had come to do some laser scanning, it was too late: The prints were barely visible.
Panicked, scientists lifted from the site a 130-pound block of sediment with one faint print on top, to have it analyzed at the National Oceanography Center. It is the only remaining physical evidence of the footprints: Before the month was out, all traces of them had vanished. It was a powerful reminder of both the resilience and the fragility of human life.
“What had been preserved for nearly one million years was taken back by the sea in the space of 10 days,” Dr. Ashton said.
Initially skeptical, he said he knew the footprints were real when Dr. Duffy’s computer images landed in his inbox sometime last June. “I thought, bloody hell, we are dealing with something quite extraordinary here,” he said.
The footprints, the oldest known outside Africa, probably belonged to a family group of Homo antecessor, a cousin of Homo erectus that possibly became extinct when Homo heidelbergensis from Africa settled in Britain about 500,000 years ago, he said. Using foot-length-to-stature ratios, scientists estimate that the male was perhaps 5 feet 9 inches tall, and the smallest child a little less than 37 inches.
Little is known about this early human species. Fossil skeletons in Atapuerca, Spain, from around the same time suggest that they walked upright and looked much like modern humans, though their brains were smaller. If they had language, it was primitive. Living at the tail end of an interglacial era, as winters were growing colder, they may have had functional body hair. So far, there is no evidence that they used clothes, shelter, fire or tools more complex than simple stone flakes.
But despite their elusiveness, the human ancestors in whose footsteps modern-day Britons walk - literally - have fascinated the nation. Before some basic tools were found here in 2010, it had been believed that humans had entered Britain much later, about 700,000 years ago, Dr. Ashton said. (Before 2005, when another set of tools was discovered in Suffolk, the presumed date was 500,000 years ago.)
“British civilization started in Norfolk,” a headline in The Times of London put it at the time. A blog post by Dr. Ashton on the British Museum website on Feb. 7, when the paper he co-wrote about the footprints appeared, had more hits than any other post on the museum’s site before or since.
“We can reconstruct the climate and climate change nearly one million years ago,” Dr. Ashton said. “The big lesson is, we have to adapt. Whether we like it or not, the climate will change - it always has - and today we are accelerating that change.”
Standing on the ridge above Cardigan Bay in Borth, Dr. Bates described what the area would have looked like at the height of the last ice age some 20,000 years ago: more than half a mile of ice overhead and dry land stretching across today’s North Sea. The sea level was 400 feet lower than it is today.
“You could have walked from Denmark to Yorkshire in those days,” he said.
About 10,000 years ago, temperatures warmed sharply, by eight to 10 degrees Fahrenheit. By that time, the European ice sheets had melted, but the much thicker North American sheets took much longer. While the climate had warmed to today’s levels, allowing mixed oak woodland to grow and humans to recolonize Britain, the sea level remained some 130 feet lower for another 3,000 years.
When it did rise, it would have been traumatic for the population, wiping out whatever settlement there was, and eventually the forest of Borth. The displaced humans of the time, Dr. Bates said, were prehistoric refugees from climate change.
“Even in the reduced life span of the day, the coastline would have advanced dramatically,” said Dr. Bates, who is convinced that stories like Cantre’r Gwaelod originated in this period.
Similar tales abound on the western European seaboard: There are Cornish and Breton versions, and variations of the theme exist in Jersey and the Orkney Islands. The ultimate legend, of course, is Atlantis, which Plato placed somewhere in the North Atlantic.
“It was a traumatic geological event, and people turned it into a story to make sense of it,” said Gerald Morgan, a retired head teacher and local historian in nearby Aberystwyth.
The same thing is happening again today, as Britons survey the damage of the past couple of years of flooding and storms and ponder the future. The submerged forest in Borth, little known outside a small radius here, has once again become part of local lore. Its haunting shapes are featured in poetry slams and in storytelling evenings, and modern-day performances of Cantre’r Gwaelod have been staged on the beach, said Mr. Morgan and his wife, Enid.
Have they ever heard the bells?
Mrs. Morgan smiled. “I knew someone who did.”
Searching for Answers in Very Old DNA
By Caludia Dreifus, The New York Times, June 23, 2014
As he puts it in the subtitle of his memoir, “Neanderthal Man,” Svante Paabo goes in search of lost genomes. Dr. Paabo, a 59-year-old Swede who leads his own laboratory at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, was the first to extract and sequence the genomes of the ancient humans called Neanderthals and Denisovans, and to compare them with those of modern humans. Genes, and the stories they tell, are texts he reads.
We recently spoke for three hours in Washington, and later on the telephone. Here is an edited and condensed version of our conversation.
Q. DID YOU ALWAYS WANT TO BE A GENETICIST?
A. I wouldn’t say so. When I was 13, my mother took me to Egypt. That made a big impression; afterward I thought I might become an Egyptian archaeologist. I had a very romantic idea what that would be
like: discovering mummies and pyramids and things like that. I even started studying Egyptology at the university. But there, my romantic ideas caught up with reality. In the 1970s, Swedish Egyptology was very linguistically oriented. It was about ancient word forms and translating hieroglyphics. I couldn’t imagine spending my life with it.
Q. HOW DID YOU COME TO INVENT AN ENTIRELY NEW RESEARCH AREA, THE GENETICS OF ANCIENT HUMANS?
A. In the late 1970s, while I was doing my medical studies [at Uppsala University in Sweden], these new techniques for studying DNA wereintroduced - cloning, sequencing. I was amazed by them and learned how to do them.
And that brought me to thinking again about Egyptian antiquities. I knew that there are hundreds of mummies stored in museums across Europe. Mummies, after all, are the dried-out bodies of dead people or animals. I wondered if in some, their DNA might still be preserved. If it was present, we could study it just as we study the DNA of people alive today.
My thought was, “If we could do this, we can answer many questions in history that we cannot otherwise answer.”
Q. SUCH AS?
A.Are the people who built the pyramids the direct ancestors of the people who live in Egypt today? Or: When the Neanderthals encountered modern humans, did they mix?
But to do this, one needed to obtain DNA that might be preserved in those ancient human remains. In the 1970s, many people thought that DNA was so sensitive a molecule that it probably degraded within hours of death. I thought I should test that idea. So I bought a piece of calf’s liver and dried it in an oven. The DNA survived!
Encouraged, I went on to test for DNA in some Egyptian mummies kept in our small museum in Uppsala. However, I couldn’t find any DNA in a single one. Eventually, my Egyptology professor, who had some
contacts in what was then East Germany, arranged for me to go to the Bode Museum to collect samples from their large collection of mummies.
Back in Uppsala, I studied the samples from the Bode mummies under a microscope, always searching for the remains of a cell nucleus. This is a part of the cell where the genome is located. After a few weeks, I detected a cell nucleus that appeared to contain preserved DNA. This was so encouraging.
Q. IN 2010 YOUR RESEARCH GROUP SEQUENCED THE NEANDERTHAL’S GENOME. DID IT SHOW THAT THE GROUPS HAD MIXED?
A. When we compared the Neanderthal genome to the genes of today’s humans, it showed they had. If your ancestry is from Europe or Asia, 1 to 2 percent of your DNA comes from Neanderthals. Sub-Saharan Africans don’t have Neanderthal genes because the Neanderthals never were there.
Q. YOUR LABORATORY IDENTIFIED A NEW GROUP OF EXTINCT HUMANS. HOW DID YOU COME TO DISCOVER THEM?
A. Some Russian colleagues sent us a tiny little bone fragment they’d found in a southern Siberian cave two years earlier. At first I thought it was a Neanderthal or a modern human. Yet as we began to sequence its DNA, it became clear it was neither.
Soon we saw that the ancestors of this child, a girl, had a common ancestor with Neanderthals. It went back very far, though - at least 200,000 years. We also saw that her group had a long history independent of the Neanderthals. So now it was clear: we were working on the genome of a human group that wasn’t known before.
This was the first time a new form of extinct human had been described from genome sequences and not fossil bones. We named them Denisovans, after the Denisova Cave, where the bone had been found.
As with the Neanderthals, we wondered if the Denisovans had contributed genes to human populations today. It turned out that they had. We found that they contributed DNA to people in the Pacific region -
in New Guinea and some of the islands.
Q. HOW DO YOU THINK THAT HAPPENED?
A. Beyond what the genome says, one can’t know. The easiest explanation is that when modern humans came through South Asia, they encountered Denisovans, bred with them and continued migrating.
Q. WILL THERE BE MORE HUMAN GROUPS DISCOVERED IN THE NEXT FEW YEARS?
A. Had you asked me this before the Denisovans, I would said, “Nah, we pretty much know what’s there.” But now I feel there is a lot more to be discovered. In particular, we need to look more in China. It’s unclear howthe humans who lived in China 50,000 to 100,00 years ago relate to the Denisovans and Neanderthals. So China is a very important place.
But there are interesting things in Europe too. In Spain, there’ve been some very important discoveries with 400,000-year-old Homo heidelbergensis. We are very excited that we’ve been able to get some DNA
from one of the fossils there.
Q. WHEN YOU WERE GROWING UP, DID YOU HAVE A SENSE THAT SCIENCE WOULD BE YOUR FUTURE?
A. Well, science was certainly there in the background in the family. I grew up with my mother, and she was a chemist. My father [the Nobel laureate Sune Bergstrom], he was a biochemist.
My father was someone who showed up on Saturdays and sort of took an interest in my education. He had another family. We were like “the secret family.” So when he got his Nobel Prize, we could watch that on television.
DID THAT TROUBLE YOU?
A. I had known from the time I was the tiniest baby that this is how it works. I never experienced this as a big problem. A lot of kids grow up with single mothers. I was close to my mother.
Q. DID YOUR FATHER LIVE TO SEE YOUR ACCOMPLISHMENTS?
A. He died in 2004. But I think he was proud. He was very distant. I mean, he led this double life. He could not allow himself to become very emotional with me, because where would that leave him?
Q. ON A HAPPIER NOTE, DO YOU EVER REFLECT ON WHAT AN ADVENTURE YOUR CAREER HAS BEEN? YOU GREW UP TO BECOME INDIANA JONES, AFTER ALL.
A. Yes, it has so much exceeded my wildest dreams. Rather than be the archaeologist, I ended up studying history in a new way.