They never should've had it.
It is currently the future for mankind. We have learned to expand to the stars, find new inhabitable planets, even terraform some with the right investment. All sorts of technology advanced of course, but all in all remained similar enough that someone in the present could easily adjust. Not all technology was good, however...
The Ecos, a nicknamed Eco-Terrorism group somehow got their hands on an experimental genetic modification technology and weaponized it. In short, it turns people into animals. The usual payload is a sort of explosive bomb, where the explosion is really a release of genetic-modifying materials. As with any explosion, things tend to be worse at the center of an explosion, and less severe the farther away a person is. A person will almost instantly turn into an animal at the center. Regardless, a person will fully change into an animal at some point if affected even the slightest bit.
Eco-terrorism has always taken many forms in the past, but they saw this as turning a problem into a literal solution. Fortunately due to the nature of the genetic modification and the Ecos having no major scientists of their own, the changes cannot spread. And the governments do a decent job of keeping the movement suppressed as well. Every once in awhile though, the ecos do manage to deliver a particularly successful Eco-bomb...
But the worse of all this, is the "Going Native" syndrome. It depends on person to person, and how close they were to the center of the explosion, but people do seem to act or for all intents and purposes BECOME the animal they appear to be, body AND mind. A person at the center of an explosion may extremely quickly turn into a donkey, as well as show no signs of sentience, the donkey going to nearby grass to graze or quickly running away from any sign of danger. A person farther away, but still a donkey, may change within a few hours, but still make their way to emergency crews, signifying themselves as sentient with practiced instruction. Everything seems to depend, but "Going Native" syndrome does seem to afflict all regardless overtime...
And since this has been happening, the local governments have been trying their best to help those changed by the Eco-bombs. It's not perfect, but they do try.
But now, an Eco-bomb is about to go off somewhere and change someone...