The dodo's demise was caused by humans. Now scientists think they can bring the bird back. Should they?
The wildlife of Mauritius, a tropical island in the Indian Ocean about 500 miles east of Madagascar, couldn't have known that the giant shadows cast across the bay in 1598 would signal doom.
A fleet of Dutch ships had arrived, mirroring the Chicxulub asteroid that had crashed into in the Yucatan peninsula some 66 million years earlier.
That rogue rock ended the reign of the dinosaurs in dramatic fashion. Yet the threat posed to their modern-day relatives -- creatures like the blue pigeon, the scops owl and the broad-billed parrot -- by the Dutch fleet was far more insidious. The latter wasn't an explosive end. It was a slow burn: Sailors who colonized the island destroyed its natural habitat and introduced alien species like rats, pigs and monkeys that could outcompete the island's native residents for resources.
Some species disappeared before anyone even noticed. But the most enduring emblem of the island's extinct species is, without doubt, the dodo, or Raphus cucullatus.
The dodo was wiped out no more than a century after the Dutch arrived. It's unclear exactly when because, at the time the dodo roamed the jungles of Mauritius, the idea that any animal might one day cease to exist was preposterous. "Extinction" was a word used to describe the quenching of fires, not the demise of entire species. What is clear, however, is the extinction of the dodo was partially caused by us -- humans.
Now, Texas-based Colossal Biosciences thinks it can right that wrong.
The "de-extinction company" has garnered worldwide attention in its pursuit of resurrecting the woolly mammoth and the Tasmanian tiger. It believes the resurrection of the dodo is within reach of science, too.
On Jan. 31, Colossal announced the initiation of its dodo de-extinction project, thanks to a $150 million cash injection led by the US Innovative Technology Fund. The research will be overseen by Beth Shapiro, a paleogeneticist long fascinated by the bird, and it hopes to one day introduce a "functional dodo" back to its native habitat on Mauritius.
The functional part is important. We can never perfectly bring back a species that went extinct. It's impossible.
"It would be disingenuous to say that we're re-creating something that's 100% identical to something that existed," Shapiro says. "What we're trying to do is create proxies for these species that are adapted to the environments that are there today."
As with all de-extinction efforts, there remain significant technological hurdles, ethical caveats and unanswered questions.
Proponents of de-extinction point out how advances in biotechnology, bioinformatics and genetics have made it possible to create simulacra of long-dead species, even if the process is difficult and lengthy. They suggest reintroducing these species to the wild could provide ecological benefits and even help fight climate change.
Others remain unconvinced. Some researchers have dubbed de-extinction a "fairytale science" and criticized Colossal's press-heavy approach. They often quote a familiar line, inextricably tied to de-extinction efforts, from Jurassic Park's Ian Malcolm: "Your scientists were so preoccupied with whether or not they could… that they didn't stop to think if they should."
The question, then: Should Colossal de-extinct the dodo?
The dodo has, throughout history, been characterized as a plump, clumsy bird too dumb to prevent its own demise; a tragic creature destined for extinction. Stories of its ineptitude persist today in illustrations and cultural works, like Alice in Wonderland, as well as in clichés, like "dumb as a dodo."
In the last decade, we've learned those suppositions need to be reworked.
Based on its brain size, the dodo probably had a level of intelligence comparable to one of its distant relatives, the pigeon. A study of its brain case, performed by paleontologist Eugenia Gold and colleagues in 2016, suggests it wasn't a genius, but it wasn't a dunce, either.
Researchers like Leon Claessens, a professor of vertebrate paleontology and evolution at Maastricht University in the Netherlands, have been on a pro bono PR campaign to rehabilitate the bird's reputation. The dodo's story is not about stupidity. Instead, Claessens suggests, it's a series of unfortunate events. It's a story about bad luck.
Start at our first recorded encounters with the dodo. Those Dutch sailors who happened upon the isles Mauritius weren't even attempting to reach the island. They'd been blown off-course thanks to a violent storm. That meant some of the first people to lay eyes on the bird were mariners, not naturalists or scientists. There were no biologists on board to rigorously document, record and take samples to describe the species scientifically. Unlucky.
As trade to Mauritius picked up and more Dutch arrived, there are accounts of dodos being brought back to Europe and other parts of the world. It's believed the number of live specimens that made the journey could be as low as three or four. Though we know, from accounts in the 1600s, that a live dodo did make it to London.
After death, it was preserved and put on display at the Ashmolean Museum in Oxford, but during the 18th century, a curator believed it was becoming too moldy. They chopped it up and threw the specimen into a bonfire, with only its head and feet spared. One foot later went missing. Its whereabouts remain unknown.
Today, the remaining soft tissue specimens could fit into a shoebox, says Claessens. "It's tragedy upon tragedy of continuously losing sight of this exciting bird," he says.
Scientists have been able to complement this paucity of physical specimens by visiting a Mauritian marsh known as Mare aux Songes. Well-preserved dodo fossils were discovered there in the mid-1800s, contributing to another explosion in our understanding of the bird's life and ecology, but by the 1940s, the site had fallen into neglect due to a malaria epidemic. Call it bad luck.
It's only in the past two decades that Mare aux Songes has experienced a revival, with scientists like Claessens and Shapiro visiting the site and hunting for fossils. Expeditions have uncovered plentiful bones from over 400 distinct individuals, among a mixture of other extinct Mauritian wildlife. Cruelly -- or perhaps, unluckily? -- subtropical temperatures of the marsh are not the kind of conditions that preserve DNA well.
And if you want to bring a species back from the dead, you're going to need some really good DNA.
An organism's complete set of DNA, its genetic blueprint, is known as a genome.
A genome is like a book that uses just four letters: A, C, G and T. How these letters are arranged and organized gives us the extreme variety of life we find on Earth, from dodo to door-mouse, from hippo to human.
Decoding a genome ("DNA sequencing," as the scientists say) used to be an incredibly difficult and expensive task. The human genome contains around 3 billion pairs of letters and was only completed, after a 13-year effort, in 2003. As technology has improved, researchers have been able to sequence the genome for over 3,200 species more rapidly and cheaply than ever before.
But assembling the genome of a long-dead species is a much more difficult task.
DNA might survive in fossils under the Arctic tundra and soft tissue specimens might be preserved under just the right conditions, but typically, these samples are hundreds (or thousands) of years old, during which time the DNA within them has degraded.
What this means is, in those instances, some of the A's, C's, G's and T's are missing. Depending on the sample, entire pages of this genome-book might have become lost or, at the very least, difficult to read. Other times, there may be fragments that survived but remain difficult to piece together. Shapiro's early work on the dodo used small fragments of DNA to determine where the dodo fits on the evolutionary tree, but wholly re-creating this animal would require a lot more genetic information -- and finding good samples has been a challenge.
"I've tried dozens, if not hundreds of dodos that were found in deposits on Mauritius and have not been able to recover DNA from them even using the most modern approaches," Shapiro says.
But one sample, extracted from a specimen at the Natural History Museum in Copenhagen, provided Shapiro with the high-quality DNA she needed to unravel the dodo genome. With this blueprint in hand, resurrecting a proxy species of the dodo becomes plausible. However, there are still a number of steps before the first bird cracks out of its egg.
In the mammoth and Tasmanian tiger projects, the idea is to edit the DNA of a cell and then transfer that DNA into an egg cell and create an embryo. That's not possible for the dodo.
"The key difference with birds, and why we're much further behind in trying to use any sort of gene editing or genetic engineering approaches, is that we just don't have access to the egg cell at that developmental stage," Shapiro says.
Unlike with its mammal projects, the team needs to work with primordial germ cells (PGCs) when it comes to the dodo. These are cells that can be extracted from a bird's egg -- let's say a chicken egg -- about a day after it's laid, then cultured in a dish. In the dish, scientists can make edits to the DNA of the PGCs, changing their A's, C's, G's and T's, until they become dodo-like. Then they can implant the PGCs back into the egg, which would eventually hatch into a very normal chicken, with one key change: Its reproductive cells contain some of these dodo-like cells. After fertilization, those cells might grow into dodos.
At least, that's the theory, and it's this technological hurdle Colossal will be investing in overcoming initially.
"There's some potential that we could just use chickens as the carriers for these modified PGCs," Shapiro says. "But this is something that we don't know."
De-extinction is a fledgling scientific field rife with those kinds of unknowns. Ben Lamm, Colossal's CEO, is cognizant of the challenges his teams have to overcome to bring any of their de-extinction projects to fruition -- but he firmly believes Colossal has the technical expertise, the engineering knowhow and, importantly, the funding to see these projects through.
He's also not surprised at how Colossal's previous de-extinction announcements have both excited and agitated researchers, ethicists and conservationists. He says the company has been open and transparent about its plans. But that hasn't stopped a barrage of questions from the public, the press and other scientists. "Any time you do anything big and bold, you're going to get all kinds of feedback," he says.
No matter which animal Colossal chooses to de-extinct or how it chooses to get there, a similar set of concerns arise. Julian Koplin, a bioethicist at Monash University, has been thinking through some of these issues.
He notes that there is a general anxiety about whether such a project will even work and how it will be implemented. As Koplin points out, we've never done anything like this before, which means it's hard to know the consequences. Even if Colossal meticulously plans every aspect of a dodo's reintroduction, there may be unintended consequences it could not predict.
"The other major concern we need to take very seriously is about what de-extinction will do for how we think about the environment and the urgency of protecting existing species from extinction," says Koplin. Essentially, de-extinction could reconfigure our relationship with extinction itself.
Jolyon Parish, an independent researcher and author of The Dodo and the Solitaire, a book exploring the history of the two extinct birds, shares that concern. He wonders what signals we will be sending if we show that de-extinction works, suggesting it might lessen the impetus for saving threatened species today.
There are also questions about the viability of a waddle of dodos being brought back only to find themselves in a potential genetic bottleneck, in a new home and unable to truly adapt to the environment they find themselves in. "Mauritius of today is fundamentally different to Mauritius of 1598," says Claessens, the vertebrate paleontologist from Maastricht University. Dooming the dodo a second time is a very "fool me twice, shame on you" situation.
"We know we drove them to extinction," says Eugenia Gold, a paleontologist at Suffolk University who analyzed the dodo's braincase in 2016. "But how are we going to ensure that when [we] bring them back we're not going to do that again?"
Though Mauritius and some of the surrounding islands retain features of the environment present during the dodo's time and environmental rehabilitation programs have been instigated by the Mauritian government, Shapiro notes that a reintroduction of the dodo would require a place free of invasive species like rats and pigs -- the species that drove it extinct in the first place. "If we are going to successfully reintroduce a functional dodo at some point, we'll have to find a habitat where these introduced species aren't present anymore."
Colossal is already thinking about these problems. Lamm says he has started conversations with landowners and indigenous groups in different parts of the world so they can, one day, undertake rewilding projects safely and ethically.
In some distant future, a ship might slow into a secluded port in the Indian Ocean -- perhaps on the island of Mauritius, perhaps somewhere nearby -- with an almost miraculous cargo: a handful of dodo-like birds, ready to pad along a jungle floor for the first time in over 300 years.
To realize such a future, Colossal would have had to overcome all sorts of technical challenges. It would have had to perfect avian gene editing and germ cell transfers. It would have had to find a suitable species to lay a dodo egg. It would have had to master caring for dodos in captivity, managing their health and genetic diversity. Perhaps most importantly, it would have had to prove this is worth doing, allaying any fears and anxieties about the dangers of de-extinction by engaging early with indigenous groups, conservationists, ecologists and other scientists.
But what happens if, instead, we simply let the dead lie?
The Earth is experiencing its sixth mass extinction event right now. Biodiversity is plummeting. We will lose thousands, maybe hundreds of thousands of species in the next century.
"We live at a time when habitats across the planet are changing, and species everywhere are struggling to adapt," says Shapiro. "We are sitting on the possibility of having new technologies that can actually change what is forecast for this mass extinction event that we're going through."
The future, she hopes, is one that is both biodiverse and filled with people. Investing in de-extinction may be a start, but there's something else Colossal will need on its path to resurrecting the dodo. It's something the dodo's story has always been missing and yet something that could turn its fate -- and the future of conservation -- around.
A little good luck.
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Updated Feb. 18: In the bad luck bird section we have made it clearer that Eugenia Gold's team studied the braincase of the dodo.