Anyone would consider it an exceptional adventure to travel through Siberia in search of monstrous prehistoric creatures, emerged from the depths thanks to the melting ice. For the Swedish explorer Love Dalénthat’s just another Monday. On September 3, 2018, near the remote Russian village of Belaya Gora, Dalén came across the remains of a female woolly mammoth, locked in frozen ground for 52,000 years. Genetic analysis revealed an extraordinary discovery on Thursday: the mammoth carcass retains the three-dimensional structure of your DNAa previously unseen feature that even allows us to know which genes were active. For researchers, these “fossils of ancient chromosomes” bring closer the possibility of resurrecting species that became extinct thousands of years ago.
“I have found many hundreds of mammoth specimens during my career, but this one was extraordinarily well preserved. It is probably the best preserved mammoth specimen I have found,” explains Dalén, a researcher at Stockholm University who is half from Cadiz: his wife is from El Puerto de Santa María and his daughter was born in Jerez. “Seeing that ear so well preserved is an incredible experience that I will never forget,” recalls the scientist, great-grandson of Gustaf Dalénwinner of the Nobel Prize in Physics in 1912 for inventing an automatic regulator that reduced gas consumption in coastal lighthouses that guided ships.
The new discovery is historic, but the fact that it was in a mammoth is anecdotal, the geneticist stresses. Marc Martí Renomone of the leaders of the research. The first time that ancient DNA was recovered was in 1984, in the remains of a quagmirea subspecies of zebra that became extinct in southern Africa a century earlier. Since that first quagmire, even human DNA dating back hundreds of thousands of years has been obtained, which has revealed a host of unexpected facts, such as the fact that local humans on the Iberian Peninsula disappeared some 4,000 years ago or that modern humans and Neanderthals had children more than 100,000 years ago.
“People imagine the genome as a text, as if it were one letter after another. The reality is that the genome is a physical object that is two meters long, folded in the nucleus of the cell,” explains Martí Renom in a room at the National Center for Genomic Analysis (CNAG) in Barcelona. Until now, the ancient DNA fragments recovered usually had about 100 letters. The fossil chromosomes of the female mammoth have hundreds of millions of letters. Martí Renom compares her DNA to a puzzle with 3 billion pieces. The discovery of its three-dimensional structure is like finding the photograph of the puzzle box.
The biologist Juan Antonio Rodriguezco-author of the research, believes that this advance “can contribute to the de-extinction of species”, but asks for caution. “I would not like to see a zoo, a Pleistocene Park, where you can go to see sabre-toothed tigers, mammoths, woolly rhinos, cave lions or any type of extinct animal, because I think we would be bringing back to life animals that became extinct under circumstances that are not the same as those of today. We do not know how these species would react in current climatic conditions or to humans. We also do not know if they would be genetically viable and could lead a normal life,” reflects Rodríguez, formerly a researcher at the CNAG and now a professor at the University of Copenhagen, in Denmark. Some of the last mammoths lived about 4,000 years ago on Wrangel Island, north of Siberia, according to Rodríguez. public the Love Dalén team a couple of weeks ago.
An American company, Colossal, has announced that it plans to create mammoths by 2027, or rather elephants genetically edited to have the external features of a woolly mammoth. Three of the co-authors of the new study—Swedish explorer Love Dalén, English biologist Tom Gilbert and the American geneticist Erez Aiden— are on Colossal’s scientific advisory board. The company received a boost in 2022 70 million eurosfrom investors such as Thomas Tull, producer of the film Jurassic Worldand the famous millionaire Paris Hilton. Tom Gilbert, from the University of Copenhagen, has proclaimed in a statement that the new results “have obvious implications for current efforts aimed at de-extinction of the woolly mammoth.”
Erez Aiden is the father of Hi-Ca revolutionary method for studying the three-dimensional architecture of DNA. Her Mexican colleague Cynthia Perez Pérez began investigating whether the technique also worked with damaged DNA almost a decade ago. “I started by doing very humble experiments with my dinner, with the chicken bones I had left over,” recalls Pérez, who also tried it with a roadkill mouse and the skin from her bag in her laboratory at the Baylor College of Medicine in Houston (USA). When she demonstrated that the method also worked with damaged DNA, the team immediately contacted the explorer Love Dalén, who in 2018 provided them with a sample of the female mammoth’s ear.
George Churcha global genetics guru and co-founder of the company Colossal, believes that fossil chromosomes are “a powerful tool” to study the history of life on Earth, but doubts that they will drive the resurrection of species. “The advance needed for de-extinction is not three-dimensional structure, but the ability to synthesize (or extensively edit) functional genomes of 3 billion letters. Today, we can synthesize and insert with precision between 4 and 12 million letters, and these numbers are growing rapidly,” says Church, from Harvard University (USA).
Spaniards Marc Martí Renom and Juan Antonio Rodríguez perfectly remember the day they realized that the experiment with the mammoth had worked. It was March 11, 2020, and they were at the CNAG in Barcelona, with their Mexican colleague Marcela Sandovalfrom the University of Copenhagen. They could even see that mammoths had 28 chromosomes, like elephants. “We can now understand the three-dimensional structure and study the activation patterns of specific genes. This is a milestone in the field of paleogenomics,” says Sandoval. Two days later, the government declared a state of emergency due to Covid and imposed home confinement for the population.
The pandemic was not the only obstacle to the research. On February 24, 2022, Russia invaded Ukraine and sparked a war that continues today. Obtaining samples from other mammoths to repeat the experiments is even more difficult, but the authors have succeeded with the remains of another female —possibly hunted by a sabre-toothed tiger 39,000 years ago— were found in 2010 in the Russian republic of Yakutia. The three-dimensional DNA structure shows that woolly mammoths had active genes linked to hair, cold resistance and disease defences.
The new study is published this Thursday on the cover of the specialized magazine Cell. Martí Renom, who also does research at the Centre for Genomic Regulation in Barcelona, compares the mammoth meat analysed – quickly and cold-dried 52,000 years ago – with cured meat. The Houston team made a kind of beef cured meat and tried to mistreat it. The scientists ran over the meat with a car, shot it with a shotgun, hit it with a hammer, put it in a microwave and even a pitcher from the University of Houston. local baseball team Astros He threw a ball at it at high speed. The jerky was torn to pieces, but the researchers were able to recover its chromosomes intact.
The Hi-C technique applied to ancient DNA opens the door to a new world, according to Juan Antonio Rodríguez. “I think that obtaining fossil chromosomes from Neanderthals may be a little more difficult due to the state of preservation of the samples, but, for example, from Egyptian mummies, yes. It is very likely that the fossil chromosomes are in that dried meat,” says the biologist. Seeing the three-dimensional structure of a pharaoh’s DNA would serve, for example, to see if he had active genes related to defenses against certain plagues. Geneticist Marc Martí Renom believes that the corpse of Ötzi, a man murdered in the Alps 5,300 years ago and found in the ice in 1991, also “could be a good candidate” for applying the technique.
The new study includes a surprise. The authors estimate that the three-dimensional structure of DNA could survive for 530 million years, given the right conditions. That speculation generates fascinating theories. “Interestingly, one sample [de ADN] “It could also travel quite far in that time. The only known interstellar comet, 2I/Borisov, is moving at about 32 kilometers per second. At this rate, it could reach Proxima Centauri, the nearest star outside the solar system, in 40,000 years — less than the age of our woolly mammoth sample,” the researchers write.
Erez Aiden, the father of the Hi-C technique, acknowledges the high scope for speculation, but stands by his hypotheses. “We don’t know a lot of things that are really basic in this field. And when you have no idea how something works, a lot of things are possible. Before modern telescopes and space probes offered good views of the surface of Mars, many intelligent people thought there were Martians building canals there. This was less than a century ago,” Aiden muses.
It would be absolutely incredible and amazing if we observed a comet and found DNA.
Erez Aiden, geneticist
The authors believe the DNA and proteins in the mammoth sample are in a glassy state, a substance they call chromoglass. “We know virtually nothing empirically about whether DNA can survive in deep space, let alone whether chromoglass can. It would be absolutely incredible and amazing if we looked at a comet and found DNA. That would be the big news. As a species, we are very ignorant about a lot of things and this is one of them,” Aiden adds.
The Houston researcher answers EL PAÍS’s questions as Hurricane Beryl devastates his city and leaves his laboratory without electricity. Aiden wonders what evolutionary sense there is in the fact that the architecture of a mammoth’s DNA is preserved for 52,000 years. “Woolly mammoths are not plants dependent on seed production that go into a state of dormancy and are revived later. It seems that the essence of life, at its most fundamental core, is super-durable. And it is not so obvious why it is so incredibly durable. There is a mystery here,” argues the American geneticist.
Aiden floats one hypothesis: panspermia, the theory that life travels through the universe on comets and asteroids. In that scenario, it would make sense for genetic material to be as resilient as that of the mammoth. The oldest DNA ever recovered comes from a 2-million-year-old forest in northern Greenland. Erez Aiden also floats another, less tantalizing hypothesis. “It could also be pure chance,” he says. “I’ve said it before: as a species, we’re very ignorant about a lot of things, and this is one of them.”
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