‍What’s happening? Colossal Biosciences has announced plans to revive the functionally extinct northern white rhino within four years using gene editing, stored sperm and eggs from the last two living females, Najin and Fatu. The US biotech, valued at $10bn, intends to implant embryos into surrogate southern white rhinos, which number over 15,000. To boost genetic diversity, DNA from long-dead rhinos held in museums and private collections will be edited into the embryos. Earlier embryo transfers had failed due to limited genetic variability. The initiative complements existing efforts by the BioRescue Consortium and highlights the growing role of synthetic biology in conservation. (Bloomberg)

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Why does this matter? Human activities are a key driver of extinction rates, with the destruction of natural lands for construction, agriculture and infrastructure resulting in biodiversity loss. Additionally, chemical, light and sound pollution are negatively impacting wildlife, as are diseases spread by invasive species that are expanding their reach due to global warming. Overhunting and poaching are other serious factors, as was the case for the decline of the northern white rhino. Meanwhile, climate change poses a major threat, especially to species with a limited habitat range. The International Union for Conservation of Nature’s (IUCN) latest Red List of Threatened Species now includes 172,620 species, with 48,646 at risk of extinction.  

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Back from the dead – Colossal hit the headlines earlier this year when it declared it had resurrected the dire wolf, last seen over 10,000 years ago. Scientists decoded its genome from ancient remains, enabling them to make 20 edits in 14 genes of the common grey wolf, the dire wolf’s closest living relative, to revive traits such as more powerful shoulders, more muscular legs, a white coat and distinctive howls and whining. Resulting embryos were implanted into domestic hound mixes as surrogate mothers, leading to the births of three pups, Romulus and Remus, both male, and female Khaleesi.

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A mammoth task – Other bold ambitions held by Colossal include the revival of the woolly mammoth. It has already developed mice with “mammoth-like traits” with the aim to create genetically modified hairy Elephants adapted to withstand the cold, with the first expected to arrive by 2028. The firm argues that creating herds of these creatures and setting them free into the wild to interbreed would have climate benefits. It believes their grazing habits could help arctic grasslands to recover, reducing the amount of CO2 emitted by melting permafrost. The firm is also targeting the “de-extinction” of the Dodo, the Tasmanian tiger and the giant moa.

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Challenges ahead – While the return of extinct species is a potentially exciting prospect, there is much scepticism among the research community. For example, Clare Palmer, a professor of environmental philosophy at Texas A&M University, said that rather than de-extincting, scientists are “creating something else”. Difficulties include fragmented DNA, lack of mitochondrial DNA and differences in surrogate wombs. Additionally, a revived creature would experience a different climate and encounter new microbes and invertebrates, while the social and behavioural dynamics that shaped its evolution would be absent. This raises the question of whether they would survive or cause harm to other existing species, potentially increasing extinction rates.

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Nature conservation remains vital – Another major concern is that industry and politicians may perceive de-extinction as a method to reverse environmental damage. Indeed, as Colossal revealed the arrival of the dire wolf, US Secretary of the Interior Doug Burgum wrote on X that the event was a “time to fundamentally change how we think about species conservation”, adding that the “technology can help forge a future were populations are never at risk”, before taking a swipe at the endangered species list – presumably the IUCN’s Red List – claiming that 97% of species added “remain there.” However, this sentiment neglects the reasons for extinction in the first place – without a habitat, creatures cannot live, meaning that ongoing nature conservation efforts, such as the goal to stop and reverse deforestation by 2030, remain vital.