Scientists are working to bring back the dodo, a bird widely recognized as a symbol of human-caused extinction. These efforts represent a significant step in de-extinction, aiming to reverse the disappearance of species. The dodo’s story highlights the impact human activities can have on biodiversity.
The Dodo’s Legacy
The dodo (Raphus cucullatus) was a flightless bird found exclusively on Mauritius, an island east of Madagascar. Its large size and inability to fly adapted it to an environment with few natural predators. Humans arrived in the late 1500s, leading to the dodo’s rapid decline. Introduced species like rats, pigs, and macaques preyed on eggs and competed for food, while habitat destruction through logging further reduced their numbers. The last widely accepted sighting occurred in 1662, making its extinction a stark example of biodiversity loss driven by human actions.
The Science of Bringing Back Extinct Species
Bringing back extinct species involves complex scientific methods, beginning with the retrieval of viable genetic material. Scientists obtain ancient DNA from preserved specimens, which provides the blueprint for the extinct organism. This recovered DNA is often fragmented, requiring advanced sequencing techniques to assemble a comprehensive genome. Once the extinct species’ genetic code is mapped, genetic engineering tools, such as CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats), become central to the process.
CRISPR technology acts like molecular scissors, allowing scientists to make precise edits to DNA, inserting or deleting specific genetic information. This involves identifying the traits that defined the extinct species and editing the genome of a closely related living species to incorporate these characteristics. While cloning through Somatic Cell Nuclear Transfer (SCNT) has been successful with mammals like Dolly the sheep, it presents significant challenges for birds due to their unique reproductive biology. For avian species, the edited cells would be used to create embryos, which then require a living relative to act as a surrogate, carrying the embryo to term.
The Dodo De-extinction Project
Current efforts to revive the dodo are being spearheaded by Colossal Biosciences, a biotechnology and genetic engineering company. A key milestone was achieved when scientists at the Genomics Institute at the University of California, Santa Cruz, in collaboration with Colossal, successfully sequenced the dodo’s genome in 2021 using DNA extracted from a museum specimen. This comprehensive genetic map guides the de-extinction process. The Nicobar pigeon (Caloenas nicobarica) has been identified as the dodo’s closest living relative, making it the primary candidate to provide the host cells for genetic engineering. Insights from the genome of the also-extinct Rodrigues solitaire, another close relative, are also being used to understand dodo characteristics.
Colossal’s strategy involves editing the Nicobar pigeon’s genome to reflect the dodo’s traits, including its flightless nature. Adapting genetic engineering techniques for avian species is challenging, as birds have external eggs and different reproductive processes compared to mammals. The company is developing methods to work with primordial germ cells (PGCs) extracted from bird eggs, and even exploring the use of genetically modified chickens as surrogates to accelerate the production of dodo-like birds.
The Purpose of Dodo De-extinction
The dodo de-extinction project has several motivations, including ecological restoration. Reintroducing the dodo to its native Mauritian habitat could restore lost ecological functions, such as seed dispersal for plants that relied on the dodo. Colossal Biosciences partnered with the Mauritian Wildlife Foundation to prepare habitats, including invasive species removal and revegetation, for reintroduction.
The project also advances scientific knowledge and technology. It improves genetic engineering, particularly CRISPR, and avian reproductive technologies, which could have broader conservation applications. The dodo’s iconic status raises public awareness about the biodiversity crisis and conservation efforts.
Navigating the Future of De-extinction
Bringing back extinct species involves broader considerations and practical hurdles. A challenge is ensuring suitable habitats for reintroduction, especially for species extinct for centuries. Mauritius’s ecosystems have changed dramatically since the dodo’s disappearance, with persistent introduced predators.
Integrating a de-extinct animal into modern ecosystems presents complexities, as unforeseen ecological impacts could arise. Discussion continues regarding ethical implications, animal welfare, and public acceptance. Concerns include de-extinct animals becoming invasive, their health and survival, and a “moral hazard” where de-extinction might reduce the urgency of preventing current extinctions. Resource allocation is also debated, questioning if de-extinction funding could be better used for currently endangered species.