A version of the dodo bird (Raphus cucullatus) could make a return someday soon. Colossal Biosciences announced this week several milestones in its quest to bring the extinct species back to life.
On Wednesday, the Dallas-based company reported that its researchers at the Avian Genetics Group have successfully grown pigeon primordial germ cells (PGCs) in the lab, a scientific first. They also bred gene-edited chickens intended to serve as potential surrogates for the dodo and other ancient birds. Those accomplishments are crucial to the company’s plans to functionally restore the dodo to the land of the living.
“Colossal’s breakthrough in culturing pigeon PGCs solves a fundamental roadblock that has stymied bird genetic engineering for decades,” Colossal CEO and co-founder Ben Lamm told Gizmodo.
How to bring back an extinct bird
Colossal bills itself as a functional “de-extinction” company. Its stated goal isn’t to perfectly replicate the genome of an extinct animal; rather, it’s to resurrect “the key traits and ecological functions of extinct species” using the smallest amount of precise genetic edits possible, Lamm said.
Earlier this April, Colossal reported its first success: the breeding of three wolves modified to share some of the genetic makeup of the dire wolf (Aenocyon dirus), an extinct, larger relative of the gray wolf that died out nearly 10,000 years ago.
The company also has pledged to bring back and re-wild the woolly mammoth, the Tasmanian tiger, and the dodo bird. That said, resurrecting an extinct bird is an entirely different challenge compared to bringing back mammals like wolves.
“Unlike mammals that can be cloned, birds require a completely different approach. You have to edit their ‘germ cells’ (which become sperm and eggs) and then breed those edited cells into the next generation,” he explained.
Scientists have previously learned how to edit the germ cells of chickens and geese, but Colossal’s scientists are the first to have successfully tweaked the germ cells of pigeons, the broad group of birds that the dodo belongs to—no easy feat. The researchers tested 300 combinations of growth factors, small molecules, and other ingredients before finding the optimal formula for growing the edited PGCs.
The company has also bred chickens without their own germ cells, allowing scientists to insert edited PGCs in their place. Ideally, this means that when these chickens reproduce, they’ll actually lay eggs containing pigeon genetics, not chicken.
Lastly, its scientists have fully sequenced the genomes of the dodo’s closest relatives, the extinct Rodrigues solitaire (considered the dodo’s sister species) and the still-living Nicobar pigeon, the latter of which will serve as the base template for the team’s dodo revival project. This information will enable Colossal scientists to plot the genetic edits needed to make a Nicobar pigeon into a dodo-like bird.
“These advances create a clear pathway: edit Nicobar pigeon germ cells with dodo traits, inject them into surrogate chickens, breed the results, and eventually produce birds with dodo characteristics,” Lamm said.
The argument over de-extinction
While many scientists have praised Colossal for its genetic innovations—like creating its version of a dire wolf—others have criticized the company for labeling its projects as “de-extinction.”
Wolves, dodos, and other animals contain troves of genetic information, and critics have argued that the relatively few edits Colossal is performing in their specimens simply don’t come close to bridging the gaps between an extinct species and its closest living relatives.
Colossal stands by its approach, however. It notes that some conservation organizations have advocated for creating “proxy” versions of extinct species as a way to restore biological diversity in an area—a goal the company feels is aligned with its mission. Lamm also argues that since each genetic edit carries some risk, keeping them to a minimum also helps ensure the safety and health of their animals.
“We’re focused on results, not labels. Whether critics want to call our animals ‘de-extinct dodos’ or ‘dodo-functional birds’ doesn’t change their conservation value,” he said. “What matters is whether they can restore lost ecological functions, enhance ecosystem resilience, and help address the biodiversity crisis all while inspiring the next generation.”
For now, Colossal is still laying down the groundwork for its dodo project. That includes identifying the exact amount and mix of edits to induce in its Nicobar pigeon germ cells, as well as working with local researchers in the African island nation of Mauritius, where the dodo bird lived and where the company is planning to home its revived dodos. Though the company doesn’t have a firm date set yet, it’s expecting to achieve dodo de-extinction within the next five to seven years.
Meanwhile, the company’s first dire wolf successes, Romulus, Remus, and Khalessi, are reportedly continuing to thrive, with Romulus and Remus about to celebrate their first birthday next month.
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