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According to the World Health Organisation disease-carrying mosquitos kill over 700,000 people each year. This would explain our innate revulsion to the blood-sucking airborne assassins. For everyone who has at one time or another cursed the very existence of the mosquito, we have some interesting news.
Forget the mosquito repellant
Scientists at the Imperial College in London have successfully used gene-editing to wipe out an entire mosquito population - under laboratory conditions. The 'gene drive' process employed altered the DNA of the mosquitos and targetted an area of the genome that is responsible for female development. The change was self-sustaining in that it passed down through subsequent generations and prevented females from laying eggs as it spread through the breeding pool. The result was that the entire population collapsed within 11 generations. This is no small feat. It means we can circumvent nature and eliminate undesirable genetic characteristics.
The mosquitos in question were Anopheles gambiae, the species responsible for the spread of malaria in sub-Saharan African. Malaria experts have hailed the decision as an important breakthrough in a fight that (despite the eye-watering sums spent) has ground to a stalemate. Rapidly deploying a gene drive process in the wild is an attractive proposition, particularly if you currently have Malaria, or Zika, or Chikungunya.
The Bill and Melinda Gates Foundation is pouring millions into its Target Malaria campaign, a program that also seeks to utilise gene drive technology. Surely no one would mourn the passing of a species that has killed well over 400,000 people in 2016. Yet, there is a dissenting view to consider.
Playing god
Detractors of the technology argue that genetic changes are irreversible. As is extinction (at least for now). They argue that we simply don't know what the effects of such an extinction event would be. Mosquitos may well be agents of human misery, but that’s not all they are. They are also pollinators, and food for other species. This means that eliminating mosquitos could disrupt complex ecologies. There is also the possbility that the disease would simply find other paths through the eco-system. And of course, there is always a chance of intentional misuse. Some have also queried why such a potentially damaging technology is being pursued when other, gentler tactics have proven successful.
A study has been commissioned to explore just what we'll gain from losing the Anopheles gambiae. But it is not likely to consider the deeper moral question of whether human beings should wield such power.
Conservation through extinction
Many of these arguments are also playing out right now in New Zealand. It seems everything, including gene drive technology, is on the table in NZ’s bid to be free of invasive predators by 2050. Here the ethics become even more difficult: the hundreds of millions of rats, possums and weasels in Wellington's crosshairs don't threaten human life. But they were introduced to the islands by humans. So eradicating them to stop the hunting and killing of New Zealand’s beautiful and vulnerable natural wildlife may seem justifiable. And yet, all it might take is for one single rat from New Zealand to find its way to Australia, and the entire global rat population could be at risk.
As with any new technology, one thing is clear about gene drives. Our keenness to use it far outstrips our ability to understand the implications of (and to regulate) its use.
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