The dodo, Raphus cucullatus, is a global symbol for the devastating impact humans can have on the natural world. Extinct since the late 17th century, the flightless bird’s disappearance from its native island of Mauritius was caused by early human exploration and introduced species. Now, a technological pursuit known as de-extinction aims to reverse this historical loss. This concept involves using genetic engineering to recreate a functional equivalent of an extinct animal.
The Scientific Basis of De-Extinction
The foundation of modern de-extinction rests on retrieving and interpreting the fragmented genetic information of a long-dead species. Scientists must first obtain ancient DNA, which is often severely degraded. This material is then used to construct a high-quality, complete genome sequence, serving as the blueprint for the extinct animal.
Once the extinct genome is assembled, it is compared to the genome of its closest living relative. Gene editing technology, primarily using the CRISPR-Cas9 system, is employed to substitute the extinct animal’s distinctive genetic traits into the living relative’s DNA. The goal is to create a hybrid organism that phenotypically and ecologically resembles its extinct ancestor. This process creates a highly engineered proxy species designed to fill the lost ecological niche, rather than a perfect genetic replica.
The Specific Dodo Project and the Surrogate Species
The project to revive the dodo faces unique challenges because its native tropical habitat in Mauritius is not conducive to preserving DNA. Consequently, the limited genetic samples have been difficult to work with. Despite this hurdle, researchers have successfully sequenced the dodo’s complete genome, providing the necessary comparative data.
The closest surviving relative to the dodo is the Nicobar pigeon. Scientists are comparing the dodo genome with the Nicobar pigeon’s to pinpoint the specific genetic differences responsible for the dodo’s defining features, such as its large size, flightlessness, and unique beak structure. These differences are the targets for gene editing. The process for birds is particularly complex, requiring the manipulation of primordial germ cells (PGCs). PGCs are the precursor cells for sperm and eggs, and their manipulation ensures the edited traits can be passed down to offspring.
Current Progress and Projected Timeline
The de-extinction effort for the dodo is being spearheaded by the biotechnology company Colossal Biosciences. A significant milestone was the successful sequencing of the dodo genome and the establishment of a breeding colony of Nicobar pigeons. The team also recently announced a breakthrough in growing pigeon primordial germ cells in a laboratory setting. This is a necessary step for introducing the edited dodo genes.
The next stages involve editing the Nicobar pigeon PGCs with the dodo’s distinctive traits. A surrogate species, such as a genetically edited chicken, will then be used to incubate the first generations. The company’s chief executive has publicly stated a projected timeline for the dodo’s return is a rough ballpark of five to seven years. This suggests that a dodo-like embryo or chick could be created within the next few years.
Preparing the World for a Resurrected Species
Beyond the laboratory work, preparing for a resurrected species involves substantial logistical and ethical planning. The eventual reintroduction of the dodo is planned for its ancestral home on the island of Mauritius. This requires conservationists to secure and restore suitable habitat, particularly by creating predator-free zones.
The original cause of the dodo’s extinction was invasive species, such as rats and pigs, which destroyed the birds’ ground nests. Therefore, reintroduction must be preceded by comprehensive work to ensure the new animals can survive in a modern ecosystem. This effort raises complex questions regarding the ethics of allocating vast resources to bring back an extinct species rather than protecting those currently endangered. Furthermore, introducing a genetically engineered organism into a natural environment requires careful consideration of its long-term ecological impact and necessary regulatory permitting.