Eradicating the World's Most Dangerous Animal

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There is an animal that can be found on all land masses on Earth apart from Antarctica and a few small islands. The males of this species are vegan, they drink the juice from plants. The females, however, are the most dangerous animals on the planet. They drink the blood of animals while submitting their unlucky victims to infection by either yellow fever, Zika virus, or, most deadly of all, the malaria virus.

They’re called mosquitoes and people want to get rid of them. There is growing interest in a technology known as a gene drive that has the power to make malaria a thing of the past, saving millions of human lives as a result.

By changing a mosquito’s genetic makeup, the gene drive distributes a genetic alteration throughout a population, increasing presence with each generation, until all members of the population have adopted the new trait. Gene drives have been attempted in the past, with mixed success, but recent development of CRISPR gene editing technology has increased optimism. This new technology is fast, accurate, and scarily powerful.

Scientists realised that they could imitate the way that bacteria defensively cut up the DNA of invading viruses that would otherwise kill them. The CRISPR technique has two components: Cas9 (the scissors) and RNA (the guide). The enzyme Cas9 is guided by the RNA to the target DNA section then cuts it in two. The cell is then stimulated to repair the DNA in a particular way to introduce a change in the genome. This can only be done at a single cell level so is implemented when the organism is still a single-celled embryo. The DNA alteration then manifests as a phenotypic change to the fully-grown mosquito.

Crucially, for the gene alteration to propagate through  future generations, the new phenotype must make the mosquito more likely to reproduce than the rest of the population, so that these altered genes can be passed on.

Using a gene drive to reduce the spread of malaria could be done in a subtle way or a “not-so-subtle” way. The former requires altering mosquitos to develop an immunity to the malaria virus. Scientists are less than optimistic about this strategy as the malaria virus is quick to adapt to the host’s immunity. The latter way is to eradicate malaria-carrying mosquitos altogether. Several species eradication methods have been proposed including sterilisation and making all offspring male. This task proves less difficult scientifically, though more controversial ethically.

Surprisingly, even the most resolute conservationists seem optimistic about mosquito eradicating gene drive strategies. Edward O. Wilson, who has been called "the father of biodiversity", writes in his book The Creation: An Appeal to Save Life on Earth that “I’d not mourn the passing of mosquitoes… Let’s keep their DNA for future research and let them go. Let us not be conservation absolutists when it comes to creatures specialized to feed on human beings.” (pg 35)

That is the crucial point: it is human lives that would be improved. Most people rightfully consider reducing human suffering as more important morally than conserving the natural world.

But humans are not the only animals who experience suffering. Don’t we also have reason to support reducing the suffering of other animals even if it involves intervening in nature? If we support stewarding nature to improve human lives, as I believe we should, we should also support stewarding nature to improve non-human animal lives. This isn’t nearly as radical as it sounds - we have been stewarding nature in small-scale ways to help animals for centuries. Take, for example, the wildlife rehabilitation centers that provide care for injured, diseased, or starving wild animals. Gene drives would effectively be scaling these values up in order to help many more individuals.

The power of gene drives for reducing the suffering of wild animals cannot be overstated. It is conceivable that with CRISPR gene drives, diseases that plague the lives of wild animals could be eliminated, parasites could be eradicated, and animals could be altered to find their scarce habitat more bearable.

Unfortunately, humanity is not there yet. Of course, we should only implement a gene drive on a large scale when we have a better understanding of complex ecosystems and an accurate map of all possible externalities that altering a wild animal population might have on the wellbeing of their competitors, predators, and prey.

The moral picture becomes a bit more complicated when we consider that eradicating malaria carrying mosquito species is, in some sense, a permanent solution. We cannot change our minds afterwards, so the threshold of confidence in the positive outcomes of a permanent intervention like this is, quite rightly, extremely high.

But by approaching this issue from a different angle, we can see that there is a trade-off to be made. Here’s another thing that is permanent: the death and lifelong suffering of wild animals. By turning the frame on its head and considering what happens when we choose not to act, when we choose to avoid our ethical stewardship of nature, we let the lives of individual animals (and the humans who suffer and die by their millions every year due to mosquitoes) be permanently and prematurely ended in terrible ways.

As you read this, the consequences of our inaction are permanent to those who bear them. We are right to impose a high threshold to pass before we implement permanent interventions like gene drives, but we must also consider the permanent consequences of leaving killer diseases like malaria to destroy lives.

CRISPR gene drives provide us with a unique power that can influence the natural world tremendously. We must be prepared to wield this power responsibly. We also must remember that we share this planet with other sentient animals who could benefit from this technology, if we so choose to help them. The choice is only ours.


Matthew Allcock