The dodo bird, a flightless inhabitant of Mauritius, rapidly disappeared in the 17th century, cementing its status as a symbol of extinction. Today, de-extinction science explores how advanced biotechnologies might reverse the finality of extinction, offering the prospect of bringing vanished species back.
Understanding De-extinction Science
De-extinction science aims to generate an organism that closely resembles or is functionally similar to an extinct species. This process relies on various bioengineering techniques, including cloning, genome editing, and selective breeding.
One approach, cloning, utilizes somatic cell nuclear transfer (SCNT). This involves transferring the nucleus from a preserved cell of an extinct animal into an enucleated egg cell from a closely related living species. The egg is then stimulated to develop into an embryo, which is implanted into a surrogate mother. While cloning has successfully produced mammals like Dolly the sheep, it requires intact, living cells, making it more feasible for recently extinct species where such samples might exist.
Genome editing, using tools like CRISPR, offers another pathway by allowing scientists to add or remove specific pieces of DNA. This method involves sequencing the extinct animal’s genome and comparing it to that of its closest living relative. Scientists can then edit the living relative’s DNA to incorporate key traits of the extinct species, creating a hybrid organism that acts as a proxy rather than an exact genetic replica. This technique broadens the possibilities for species where only degraded DNA samples are available.
The Dodo’s De-extinction Project
Colossal Biosciences, a company specializing in de-extinction, has embarked on an ambitious project to bring back the dodo. The dodo holds particular significance as a symbol of human-caused extinction. The company aims to restore the dodo to its native Mauritian ecosystem.
The scientific approach involves using the Nicobar pigeon, identified as the dodo’s closest living relative, as a genetic foundation. Researchers have fully sequenced the dodo’s genome, a crucial step in understanding its unique genetic makeup. This detailed genetic blueprint is then compared with the Nicobar pigeon’s genome, along with insights from the extinct Rodrigues Solitaire, another close relative, to pinpoint the genetic differences that defined the dodo.
Scientists plan to use gene-editing techniques to modify the primordial germ cells (PGCs) of the Nicobar pigeon to express dodo-specific traits. These edited PGCs would then be introduced into the embryos of sterile chickens or roosters, which would serve as interspecies surrogates. The theoretical outcome is that these surrogates would produce offspring resembling the dodo. Colossal Biosciences anticipates potential dodo births by around 2028, reflecting the complex and pioneering nature of this endeavor.
Bringing Back a Species
The prospect of bringing back extinct species extends beyond laboratory science, raising significant practical and ecological considerations. Reintroducing a de-extinct species, such as the dodo, into its former habitat presents considerable challenges. The original environment may have changed dramatically due to human development and climate shifts, potentially making it unsuitable for the resurrected animal.
A reintroduced species could disrupt existing ecosystems, potentially becoming an invasive species or competing with current inhabitants for resources. The long-term ecological impacts are difficult to predict and could have unforeseen consequences. Careful planning for habitat restoration and ongoing conservation measures would be necessary to support any revived population.
Ethical debates also surround de-extinction efforts, including questions about animal welfare during genetic manipulation and cloning processes, which can involve high rates of failure and suffering. Critics argue that substantial financial resources invested in de-extinction projects might be better allocated to conserving endangered species and their habitats. Despite these complexities, proponents suggest that de-extinction could help restore lost ecological functions and enhance biodiversity, offering a new tool in the broader conservation toolkit.