Early in the morning a few days before Christmas, I was sitting in the living room of my mum's New Zealand apartment, typing away on my laptop. A parrot flew up, perched itself on the balcony railing, and stared at me expectantly, as if demanding that I bring it a treat. It was a Kaka parrot, a large, greenish-brown bird with a subtly burgundy underbelly. This bird has long been endangered in New Zealand due to forest clearing and invasive possums that compete with the Kaka for food.
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For the native species of New Zealand, European settlement was particularly cruel. The country has no endemic land predators, so many of its birds evolved without the typical avian aptitude for flight. Then came Western settlers, and along with them rats, mice, possums, stoats, cats and the occasional misbehaving dog. For these invaders, New Zealand's flightless birds were a veritable feast. Numbers dwindled. Despite conservation efforts, the country still loses about 20 of its namesake kiwi birds every week.
For more than half a century, scientists have dreamed of harnessing an odd quirk of nature -- "selfish genes", which bypass the normal 50/50 laws of inheritance and force their way into offspring -- to engineer entire species. A few years ago, the advent of the CRISPR-Cas9 gene editing technology turned this science fictional concept into a dazzling potential reality, called a gene drive. But after all the hype, and fear of the technology's misuse, scientists are now questioning whether gene drives will work at all.
The stoat -- a small, adorable, weasel-like mammal -- is the one of the largest ecological threats in New Zealand. It's a fierce invader with few predators that dines freely on the country's endangered birds. The stoat did not come to New Zealand via any unfortunate accident. It was brought there on purpose, introduced in the 19th century to control another pest introduced by settlers, the rabbit. It was, in essence, a Russian nesting doll of ecological disasters -- one bad decision supplanting yet another.
That the kiwi bird still exists at all is something of a marvel. Its native New Zealand has no endemic land predators, and so the bird evolved to be flightless. Today, its nests on the forest floor are under constant attack by invasive species -- possums, rats, feral cats and the occasional misbehaving dog.
Malaria is among the world's deadliest diseases. It killed King Tut and Genghis Khan, along with as many as half of all of the people that have ever lived. And despite modern disease management strategies like insecticides, drugs and vaccines, in 2015 malaria still killed nearly half a million people. In fact, malaria infects more people today than it did 50 years ago.
This week, researchers at UCSF announced they'd uncovered a key to making their genetically-engineered creations a lot less likely to accidentally destroy the world: A way to turn-off modifications made with the powerful gene-editing technique CRISPR. Think of it like a kill-switch for genetic engineering.
The gene drive is quickly becoming one of the most controversial technologies of our time. Its possibilities are at once spectacular and alarming: By using genetic engineering to override natural selection during reproduction, a gene drive could allow scientists to alter the genetic makeup of an entire species. This could be used to eliminate diseases and protect natural habitats -- but could also go horribly wrong in the wrong hands.
Of all the potentially apocalyptic technologies scientists have come up with in recent years, the gene drive is easily one of the most terrifying. A gene drive is a tool that allows scientists to use genetic engineering to override natural selection during reproduction. In theory, scientists could use it to alter the genetic makeup of an entire species -- or even wipe that species out. It's not hard to imagine how a slip-up in the lab could lead to things going very, very wrong.