What Alida Baileul saw through the microscope made no sense. She was looking at thin sections of a petrified skull from a young hadrosaur, a duckbill, a herbivore that roamed Montana today, 75 million years ago, when she noticed traits that made her catch her breath.
Bailleul inspected the fossils from a collection at the Rocky Mountain Museum in Bozeman, Montana, to find out how dinosaur skulls evolved. But what caught her eye should not be there, the textbooks said. Embedded in the calcified cartilage at the back of the skull were what looked like petrified cells. Some contained small structures that resembled nuclei. In one was something that looked like a stack of chromosomes, the strands that carry the body’s DNA.
Bailleul showed the specimens of Mary Schweizer, a professor and specialist in molecular paleontology at North Carolina State University, who visited the museum. Schweizer earned a doctorate in Montana under the direction of Jack Horner, a local fossil hunter who inspired Jurassic Park hero Alan Grant. Schweizer herself became known – and faced waves of criticism – for claiming to have found soft tissue in dinosaur fossils, from blood vessels to protein fragments.
Schweizer was intrigued by Bailleul’s discovery, and the two joined forces to further explore the fossils. In early 2020, as the world dealt with Covid’s arrival, they released a bomb document about their findings. Their report presents not only evidence of dinosaur cells and nuclei in hadrosaur fossils, but also the results of chemical tests that show DNA or something similar coiled inside.
I don’t think we should rule out getting dinosaur DNA from dinosaur fossils – but we won’t do it if we don’t keep looking for Mary Schweizer
The idea of restoring biological material from dinosaur fossils is controversial and profound. Schweizer does not claim to have discovered the dinosaur’s DNA – the evidence is too weak to be sure – but says scientists should not rule out the possibility of preserving it in prehistoric remains.
“I don’t think we should ever rule out getting dinosaur DNA from dinosaur fossils,” she said. “We are not there yet and we may not find it, but I guarantee we will not do it if we do not keep looking.”
Fragments of prehistoric tissue, protein or DNA could transform the field of molecular paleontology and unlock many of the mysteries of dinosaur life. But the prospect of having an intact genetic code from a tyrannosaurus or velociraptor raises questions that scientists have been accustomed to asking since the original Jurassic Park film in 1993. Armed with enough dinosaur DNA, could we bring back the clumsy beasts?
Artistic impression of the woolly mammoth. Photo: David Fleet / Alami
Rapid advances in biotechnology have paved the way for elegant approaches to extinction, in which a species once considered lost forever gets a second chance at life on Earth. For now, the focus is on beings with whom humans once shared the planet – and whom we have helped to banish from existence.
Probably the most famous extinction eradication program aims to recreate, in a sense, the woolly mammoth and return herds of animals to the Siberian tundra thousands of years after they became extinct. The company behind the venture, Colossal, was founded by Harvard geneticist George Church and Ben Lam, a technology entrepreneur who say thousands of woolly mammoths can help restore degraded habitat: for example, by felling trees, fertilizing the soil with their feces and promoting on lawns to grow again. If all goes according to plan – and maybe not – the first calves can be born within six years.
What lies ahead is a huge challenge. Although well-preserved mammoths were excavated from the tundra, no living cells have been found to clone them using the approach produced by Dolly the sheep, the first cloned mammal. So Colossal came up with a workaround. First, the team compared the genomes of the woolly mammoth and a close living relative, the Asian elephant. This reveals the genetic variants that supplied the woolly mammoth for the cold: thick fur, shortened ears, thick layers of insulation fat, and so on.
The next step is to use gene editing tools to rewrite the genome of an Asian elephant cage. If the expected 50 edits have the desired effect, the team will insert one of the “mammoth” elephant cells into an Asian elephant’s egg, the core of which has been removed. Electricity will be applied for spark fertilization and the egg must begin to divide and grow into an embryo. Eventually, the embryo will be transferred to a surrogate mother or, given the goal of producing thousands of creatures, an artificial womb that can carry the fetus until term.
The Colossal project highlights one of the biggest misunderstandings about eradication programs. Despite all the talk of returning species, these will not be copies of extinct animals. Colossal’s woolly mammoth, as Church readily admits, will be an elephant modified to survive the cold.
Whether this matters depends on the motive. If the goal is to restore the health of an ecosystem, then the animal’s behavior transcends its identity. But if the driving factor is nostalgia or an attempt to mitigate human guilt over the extinction of a species, eliminating extinction may be little more than a scientific strategy for self-delusion.
Elizabeth Ann, the first cloned black-legged ferret, at about seven weeks. Photo: US Fish & Wildlife Service / AP
The California-based nonprofit Revive and Restore is ongoing projects to help revive more than 40 species through insightful applications of biotechnology. The organization has cloned a black-footed ferret named Elizabeth Ann, which is on track to become the first cloned mammal to help save an endangered species. The hope is that Elizabeth Ann, who was created from cells frozen in the 1980s, will bring much-needed genetic diversity to wild colonies of ferrets that are threatened by inbreeding.
Revive and Restore intends to return two extinct bird species, the hen and the passenger pigeon, immediately after the 2030s. After staying for decades in Martha’s Vineyard, an island near Cape Cod in Massachusetts, the down hen eventually died in 1932. Under the plan to eliminate the extinction, scientists will create a replacement bird by editing the DNA of the closely related prairie chicken to carry hens’ genes. The Passenger Pigeon Project uses a similar approach, using the Tailed Pigeon as a genetic template.
Ben Novak, a leading scientist at Revive and Restore, likened the eradication of extinctions to re-wildlife efforts that reintroduce lost species to improve local habitats. “The introduction of biotechnology simply extends this existing practice to look at species that were previously out of the mass,” he said. Worrying that animals created through extinction projects are not exact replicas of lost species makes no sense, he added. “We do not recreate these species to satisfy human philosophy – we do so for the sake of conservation. “For conservation, what matters is the ecosystem, and ecosystems don’t sit around talking about classification schemes,” he said.
Should people try to prevent all future disappearances? Each species dies at some point. But while extinction is normal in ecosystem evolution, human activity is pushing species to the brink faster than most species can adapt. Novak says preventing all disappearances is a “good goal”, but the reality, he added, is that world governments have not given priority to protection over exploitation. “No matter how hard people work, most of humanity is still working against that goal,” he said. “What we can do is prevent as much as possible right now and diversify the world in a way that gives us environmental stability to prevent further extinction.
Dodoto: without a habitat in which to thrive, there is no point in resurrecting it. Photo: Leemage / Corbis / Getty Images
Dodoto is a major candidate for elimination. Once a native of Mauritius (and Mauritius alone), the large, flightless bird died in the 17th century after humans settled on the island. In addition to the widespread destruction of its habitat, the dodo was further threatened by pigs, cats and monkeys that the sailors brought with them.
A team led by Beth Shapiro, a professor of ecology and evolutionary biology at the University of California, Santa Cruz, sequenced the dodo genome from a museum specimen in Copenhagen. In theory, a dodo-like bird can be created by editing the genome of the Nicobar pigeon to contain dodo DNA, but, as with all extinction projects, creating an animal is not enough: there must be a habitat, to thrive in, or the exercise becomes meaningless.
“I think it’s crucial when we prioritize species and protection ecosystems, to do so by thinking about what our planet will be like in 50 or 100 years, instead of imagining that we can somehow turn the clock back. and to restore the ecosystems of the past, “said Shapiro.
“The biggest problem many species face today is that the rate of change in their habitats is too fast for evolution to continue. This is where our new technologies can be useful. We can sequence genomes and make more informed breeding decisions. We can resurrect lost diversity through cloning – such as Elizabeth Ann, the black-footed ferret – and we may even be able to move adaptive traits between populations and species. “Our new technology can allow us to increase the speed at which species can adapt, perhaps saving some from the same fate as the dodo and the mammoth,” she added.
The preserved and stuffed corpse of a young woolly mammoth found frozen in Siberia. Photo: VPC Travel Photo / Alamy
Most extinction eradication projects are viable because researchers have either living cells or …
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