Colossal Biosciences has staked hundreds of millions of dollars on the idea that extinct species can be engineered back into existence, and its dodo program is the most technically daring bet of all. The company announced what it called a world’s first breakthrough in culturing pigeon primordial germ cells, a step it frames as essential to eventually producing a bird with dodo-like traits. But a growing number of scientists question whether the end product would be a dodo in any meaningful sense, and some dismiss the entire effort as hype that diverts attention from protecting species still alive.
Why Pigeons Are the Starting Point
The dodo, a flightless bird hunted to extinction on Mauritius by the late 17th century, belongs to the family of pigeons and doves. That relationship was confirmed through mitochondrial DNA work published in Science, which placed the dodo squarely within the columbid lineage. Because no living dodo tissue exists, Colossal’s strategy depends on editing the genome of a closely related pigeon species to introduce dodo-specific genetic traits, then breeding the modified birds over successive generations.
This approach differs sharply from mammalian cloning. Birds cannot be cloned from samples of skin or hair the way Dolly the sheep was produced, because avian eggs develop inside hard shells that prevent the nuclear transfer techniques used in mammals. That biological barrier means any avian de-extinction project must work through primordial germ cells, the precursor cells that eventually become sperm or eggs. Getting those cells to survive and multiply in a lab dish is the gateway to every downstream step.
The Pigeon Cell Breakthrough, in Detail
Colossal’s team screened more than 300 culture conditions before landing on a protocol that kept rock dove primordial germ cells alive and dividing for more than two months, with a 35-hour doubling rate. The cells were then injected into surrogate pigeon embryos, where they migrated to the gonads and colonized reproductive tissue. That functional migration is the critical proof of concept: it suggests the cultured cells retain the biological capacity to contribute to the next generation.
The underlying data were posted as a bioRxiv preprint and submitted for peer review. The manuscript, titled “Long-Term Rock Dove (Columba livia) Primordial Germ Cell Culture: A Tool for Avian Conservation,” describes growth performance, maintenance protocols, and the functional validation experiments. Until the work clears independent review, its claims carry the standard caveat of any preprint: the results have not yet been evaluated by outside experts through a formal journal process.
The pigeon germ cell work builds on a decade of advances in avian reproductive biology. Long-term culture of primordial germ cells has already been demonstrated in chickens, and researchers have used similar approaches to generate transgenic poultry lines for agriculture and conservation. A 2021 study in Nature Biotechnology on avian germline manipulation helped establish many of the techniques Colossal is now adapting to pigeons, including the use of growth factors and feeder layers to keep these cells in a stem-like state.
Funding Surge and the Road Ahead
Alongside the cell-culture announcement, Colossal disclosed an additional $120 million in funding for species expansion. The company had previously raised about $200 million directed toward its dodo work and related platforms, pushing its total capital well above $300 million. That war chest is split across three flagship programs targeting the woolly mammoth, the thylacine (Tasmanian tiger), and the dodo, though the company has not published a detailed breakdown of how the new funds will be allocated among projects.
The technical plan for dodo de-extinction, as described in reporting by Nature Biotechnology and in a separate publisher overview, involves multiplex genome editing and germline technology. In practice, that means using CRISPR or similar tools to make dozens or hundreds of simultaneous edits to a pigeon genome, converting it toward dodo-like sequences, and then using the cultured primordial germ cells to carry those edits into living birds. Each of those steps remains an active research challenge, and surrogacy constraints in birds add another layer of difficulty that mammalian programs do not face.
Even if the technical hurdles are cleared, the path from a lab-bred, heavily edited pigeon to something resembling a wild dodo is long. Colossal has spoken about iterative breeding, where edited birds are crossed and selected over multiple generations for traits such as body size, beak shape, and plumage that more closely match historical descriptions and museum specimens. That selective breeding would be guided by comparisons between reconstructed dodo genomes and those of modern pigeons, but the number of genetic variants involved in complex traits such as behavior or metabolism is still poorly understood.
What Scientists Actually Doubt
The skepticism runs deeper than technical feasibility. When Colossal first unveiled its dodo ambitions, critics flagged two immediate concerns: that the project would divert resources from conservation of living endangered species, and that the biological result would not truly be a dodo. Those objections have only sharpened as the company has raised more money and made bolder claims.
Some researchers doubt whether this is de-extinction at all, with some describing Colossal as an empty generator of hype. The core argument: even if every edit succeeds, the resulting animal would be a genetically modified pigeon carrying selected dodo traits, not a dodo resurrected from its own lineage. Its behavior, microbiome, and ecological role would be shaped by its pigeon surrogate mother and a world that has changed radically since the 1600s.
That definitional dispute matters beyond semantics. As one recent assessment put it bluntly: “They didn’t de-extinct anything.” If the public and investors believe they are funding the literal return of a lost species, but the scientific community views the product as a novel engineered organism, trust can erode quickly. Conservation biologists worry that such confusion could also warp policy, leading governments or donors to prioritize spectacular de-extinction projects over the slower, less glamorous work of habitat protection.
Nature has previously chronicled how Colossal’s plans for mammoths and dodos have sparked debate among ecologists and ethicists. In one news analysis, marine biologist Boris Worm warned that the promise of bringing back charismatic species risks distracting from the urgent need to prevent further losses. He and others argue that the focus should be on preserving existing biodiversity rather than attempting to reconstruct fragments of what has already vanished.
Conservation Value or Costly Distraction?
Colossal counters that the same tools needed for de-extinction can help living species. The company and its academic collaborators emphasize that improved germ cell culture, multiplex genome editing, and reproductive technologies could enable genetic rescue of endangered birds by, for example, moving adaptive variants between fragmented populations or preserving germlines from species with dwindling numbers. In that framing, the dodo is a high-profile test case for platforms that might later be deployed for conservation.
Some conservationists accept that argument in principle but question the priorities in practice. They note that many threatened species face immediate pressures from habitat loss, invasive predators, and climate change that cannot be solved in the lab. For those critics, spending hundreds of millions of dollars on speculative de-extinction programs while existing species slide toward oblivion looks like a misallocation of scarce attention and money, even if some technological spillover eventually materializes.
There are also practical questions about what would happen if dodo-like birds are ever produced. Mauritius has changed dramatically since the 17th century, with extensive development and new species introduced. Releasing a reconstructed bird into that landscape might do little to restore lost ecological functions, and could even create unforeseen problems. Captive populations in zoos or research facilities might avoid those risks but would also undercut claims that de-extinction is a meaningful conservation tool.
A High-Stakes Experiment in Biology and Public Perception
For now, Colossal’s cultured pigeon germ cells are best understood as an enabling technology, not a guarantee of dodo revival. The company still must demonstrate precise and efficient genome editing in those cells, show that edited germ cells reliably produce viable offspring, and navigate regulatory and ethical reviews for any eventual release. Each step will invite fresh scrutiny from scientists who remain unconvinced that the endpoint justifies the means.
At the same time, the project is a live experiment in how biotechnology is communicated to the public. The language of “resurrection” and “bringing back” extinct species is powerful, but it sits uneasily alongside the technical reality of engineering new organisms that only approximate their long-lost counterparts. Whether Colossal’s dodo ultimately hatches or not, the company’s efforts are forcing researchers, conservationists, and regulators to confront what de-extinction should mean, and what society is really trying to achieve when it reaches for the past with the tools of modern genetics.
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*This article was researched with the help of AI, with human editors creating the final content.
