It’s been decades since Australia’s thylacine, known as the Tasmanian tiger, was declared extinct and scientists say they’ve made a breakthrough as they research ways to bring back the carnivore. 

Colossal Biosciences in a Thursday press release said its reconstructed thylacine genome is about 99.9% complete, with 45 gaps that they’ll work to close through additional sequencing in the coming months. The company also isolated long RNA molecules from a 110-year-old preserved head, which was skinned and kept in ethanol. 

“The thylacine samples used for our new reference genome are among the best preserved ancient specimens my team has worked with,” said Beth Shapiro, Colossal’s chief science officer and the director of the UCSC Paleogenomics Lab, where the samples were processed. “It’s rare to have a sample that allows you to push the envelope in ancient DNA methods to such an extent.”

Efforts to bring back the Tasmanian tiger

The preservation of a complete Tasmanian tiger head meant that scientists could study RNA samples from several important tissue areas, including the tongue, nasal cavity, brain and eye. It will allow researchers to determine what a thylacine could taste and smell, along with what type of vision it had and how its brain worked, according to Andrew Park, a member of Colossal’s Scientific Advisory Board and a researcher at the University of Melbourne’s TIGRR Lab.

“We’re getting closer every day to being able to place the thylacine back into the ecosystem – which of course is a major conservation benefit as well,” Pask said.

Pask, speaking with 60 Minutes earlier this year, said researchers were working with the closest living relative of the Tasmanian tiger — a small marsupial called the fat-tailed dunnart — as a way to bring the animal back. 

“But that little dunnart is a ferocious carnivore, even though it’s very, very small,” Pask said. “And it’s a very good surrogate for us to be able to do all of this editing in.”

Scientists have been comparing the DNA of the dunnart and the thylacine, Pask told 60 Minutes. From there, it’s a matter of going in and editing the DNA to turn a fat-tailed dunnart cell into a thylacine cell.

Colossal Biosciences on Thursday said it had edited more than 300 unique genetic changes into a dunnart cell, making it “the most edited animal cell to date.”

“We are really pushing forward the frontier of de-extinction technologies,” Pask said, “from innovative ways of finding the regions of the genome driving evolution to novel methods to determine gene function. We are in the best place ever to rebuild this species using the most thorough genome resources and the best informed experiments to determine function.”

Efforts aiding the revival of the Tasmanian tiger are not confined to Australia. Last year, scientists recovered and sequenced RNA from a 130-year-old Tasmanian tiger specimen preserved at room temperature in Sweden’s Museum of Natural History. 

How the Tasmanian tiger died off

Thylacines roamed Tasmania for thousands of years. Despite the Tasmanian tiger moniker, the carnivores were marsupials, like kangaroos, koalas and Tasmanian devils.

The local government in the late 1800s paid out bounties to hunters presenting carcasses of Tasmanian tigers because the animals had been eating farmers’ sheep, 60 Minutes previously reported. By the mid-1930s, the Tasmanian tiger population had dwindled to a single thylacine at the Beaumaris Zoo in Hobart, Tasmania’s capital. It died there in 1936.

Australia has similarly allowed the culling of Kangaroos, approving the deaths of thousands of kangaroos over the years. Officials have said the kangaroo population was eating through grassy habitats of endangered species. Officials have also warned in the past that there isn’t enough food available to sustain large kangaroo populations. 

New Delhi — Scientists say Indian farmers’ eager uptake of a painkiller for their cattle in the 1990s has led to the inadvertent deaths of half of a million people and massive economic losses — not from any harm to the cattle, but from the loss of millions of vultures, scavengers that historically devoured animals’ remains before they could rot and become vectors for disease.

In early 1990s, the patent on a painkiller called diclofenac lifted, making it cheap and widely available for India’s massive agricultural sector. Farmers use it to treat a wide array of conditions in cattle. But even a small amount of the drug is fatal to vultures. Since the beginning of its widespread use in India, the domestic vulture population has dropped from a whopping 50 million to just a few thousand — and according to a study published by the American Economic Association, the impact on humans has been monumental, reflecting the vital role the scavengers play.

Vultures have been a crucial part of India’s ecosystems for centuries. According to the authors of the study, entitled “The Social Costs of Keystone Species Collapse: Evidence From The Decline of Vultures in India,” the large, homely birds are a “keystone species” — one that plays an irreplaceable role in an ecosystem. 

They’re the only scavengers that feed entirely on carcasses, and they do it extremely efficiently, quickly devouring the remains and leaving little behind to spread disease. The study authors say India’s vultures would typically eat at least 50 million animal carcasses every year, before their population was decimated.

In doing so, they prevented the dead farm animals from rotting, and the deadly bacteria and other pathogens that thrive in carcasses from being transmitted into human populations.

“In a country like India with prohibitions on eating beef, most cattle end up turning into carcasses,” Anant Sudarshan, an associate professor of economics at the University of Warwick in England, who co-authored the study, told CBS News. “Vultures provide an incredible disposal service for free. … A group of vultures takes about 45 minutes to turn a cow carcass into bone.”

The vultures’ keen appetite also helped keep the populations of competing scavengers in check, such as feral dogs and rats, which can transmit rabies and a host of other diseases.

In 1994, farmers began giving diclofenac to their cattle and other livestock. The drug causes kidney failure and death in vultures that feed on the carcasses of animals given the painkiller, and the population of the birds shrank from 50 million to just 20,000 over the course of the ensuing decade alone.

Without the vultures around to do the job, farmers started disposing their dead livestock in local bodies of water, which caused water pollution — and another way for pathogens to reach humans.

Sudarshan and study co-author Eyal Frank, an environmental economist at the University of Chicago Harris School of Public Policy, examined the impact of the drastically reduced vulture population on human health by mapping vulture habitats with health data from more than 600 districts in India. They said their research shows 100,000 human deaths every year between 2000 and 2005 could be linked with the decreased vulture populations. 

It also shows economic losses they estimated at $69 billion per year, largely associated with premature human deaths due to the collapse of the scavenger population.

These deaths were caused, according to their research, by the spread of diseases that a thriving vulture population would have mitigated. Stray dog populations, and with them, the spread of rabies, also increased during the timeframe, as did the amount of bacteria measured in many local water sources.

“India is now the largest center of rabies in the world, as the feral dog population has grown dramatically,” Sudarshan told CBS News.

Without a major vulture rebound, the study authors said the spread of disease and resulting deaths will only continue in the coming years, as will the costs associated with health care.

India did ban diclofenac for veterinary use in 2006, but Sudarshan said the ban needs to be enforced much more effectively. He and Eyal have called for more conservation funding to boost vulture populations, but they’ve warned that even if the Indian government does mount a major effort, it will take at least a decade for the species to bounce back to the extent required because they’re “slow reproducers.”

As an alternative to bringing the vultures back, Sudarshan said India could build a network of incinerators around the country, but the estimated cost of that is about $1 billion per year, and they would use a huge amount of energy and create considerable air pollution, which is already a major problem for India. 

“So, it makes more sense to bring back the natural way of dealing with the millions of animal carcasses that India produces each year,” he said.

And he said that work must start urgently, as the “vultures began dying in the 1990s. India has not done anything three decades on.”

The government does spend about $3 million per year to save India’s native tigers. Sudarshan said while vultures may be far less of a tourist attraction, there’s a broader question about “the basis of our conservation policy.”

“Our paper shows that the cost of losing them [vultures] is about $69 billion a year, which is far higher than any benefits the tiger” brings, he said, adding: “We need to think from a cost effectiveness point of view and growth view, how should we pick species to conserve?”

“Understanding the role vultures play in human health underscores the importance of protecting wildlife – and not just the cute and cuddly,” said his co-author, Frank. “They all have a job to do in our ecosystems that impacts our lives.”