De-extinction: Should We Revive Extinct Species?

Thinking of resurrecting an extinct species? Dodos, passenger pigeons and woolly mammoths could be walking the earth again due to recent advances in breeding, genetics, and cloning technologies. But raising the dead also raises difficult ethical questions, with many scientists and conservationists jumping in on both sides of the debate. How can we implement de-extinction safely and responsibly? Should we be doing it at all?

On the idealistic side of the debate, writer and The Long Now Foundation president Stewart Brand argues passionately in favour of de-extinction. He imagines children captivated by woolly mammoths in zoos and describes ‘species brought back from extinction’ as ‘beacons of hope’. He even suggests that, through de-extinction, humankind may find ‘redemption’ for the damage we’ve done to the planet.

These claims are certainly attractive and exciting. Yet Brand’s argument raises significant questions about the purpose of de-extinction. As his reference to zoos hints, one of the most pressing problems surrounding de-extinction is where these animals will live and what their function will be. Will they be tame visitor attractions, a novelty that eases our guilt over our environmental impact? Or will they be released back into the wild and left to fend for themselves?

A major motivation for reviving lost species is to restore their former ecological roles in nature. However, previously extinct species can’t simply be dropped back into the habitats that were once their home. Ecosystems are constantly evolving as the many species supporting them continue to interact in complex ways. Habitats can also change drastically, such as through urbanisation or deforestation. Many species become extinct precisely because of habit loss. The ecosystem previously inhabited by the lost species may have changed significantly since it last lived. Even the resurrected dead need a home.

Yet the environment isn’t the only factor that could change: the revived species could also be significantly different. They may not have the same instincts or learning opportunities, meaning that they need to be conditioned for the wild – tricky enough in captive-bred endangered species which are direct descendants of their wild counterparts. Crucially, a revived species isn’t a simple clone. To create the extinct passenger pigeon, for example, genetic material would be extracted from, say, a museum specimen, and then combined with some genes of a living relative, such as the band-tailed pigeon. Although it would share some genetic material and hopefully look and act in similar ways, the species created in the lab wouldn’t actually be identical to the original. This means that there is no way to predict what its role and effect would be within the ecosystem. Essentially, de-extinction would be introducing a new species to an established ecosystem. Think rabbits in Australia: a seemingly harmless, non-native species that was introduced in small numbers but bred exponentially, became invasive and continues to cause environmental damage. An undesirable situation, however fluffy and cuddly the culprits.

Whether positive or negative, the consequences of reintroduction are difficult, if not impossible, to predict, control or reverse. Failure to consider when and how populations should be managed – or even eradicated – would be a failure in our responsibilities both to the revived species themselves and to present ecosystems. Extra resources will be needed to protect these new species, who could be considered endangered for quite some time, if not indefinitely. Yet such resources are already lacking. As well as this, there’s also a risk that governments may be less likely to invest in conservation if extinction is seen as easily reversible.

Yet despite these challenges, with planning and prioritisation, de-extinction could still prove useful. Three new recommendations issued by a team of researchers at the University of California, Santa Barbara may provide a way forward. The recommendations explore ways in which de-extinction could be used responsibly to aid conservation efforts, creating a positive and meaningful effect on present ecosystems.

The first recommendation is to choose recently extinct species. Re-integration into present ecosystems should be easier as their previous environment has had less time to change, thus reducing the re-introduction risks discussed above. Species with irreplaceable ecological functions are also recommended. For example, the Réunion giant tortoise, hunted to extinction, dispersed plant seeds throughout its island habitat in the Indian Ocean. Without the tortoises to disperse seeds, these plants themselves are moving closer to extinction. Reviving these tortoises would therefore help to rebalance the ecosystem. Double points for conservation. The third guideline suggests choosing species that can be restored to an effective level of abundance. In other words, a single animal will have minimal impact, but many performing that same function could effectively change the ecosystem. By carefully prioritising certain species in these ways, it might be possible to reduce the risks of de-extinction.

An alternative approach would be to apply de-extinction techniques to living species close to extinction, such as the Tasmanian devil. Wild devil populations have declined rapidly due to a transmissible face cancer thought to be caused by a single gene. Silencing this gene in a group of devils could eventually eradicate the cancer in the wild, as the immune animals continued to reproduce. Restoring genetic variability to species with small populations in this way would help the species survive.

As seductive as the idea may be, resurrecting extinct species isn’t a simple process or solution. Within larger environmental problems, de-extinction is only one tool amongst many. However, the science could prove extremely useful and, if used cautiously and alongside other conservation methods, it could be a very attractive answer to certain ecological problems.

[Sarah Spence]


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