Neurotoxins are among the most poisonous substances known. An ounce of botulinum toxin, produced by the bacterium Clostridium botulinum, if properly administered would kill everybody on this planet. Fortunately the bacterium that produces it is killed by oxygen but it sometimes occurs in tined foods that haven’t been processed properly then there are outbreaks of botulism, a potentially fatal form of food poisoning. The toxin works by paralysing smooth muscle and so your heart stops beating (among other things). In Botox treatment a weak extract of the bacterium is injected into the face and makes smooth muscle under the skin relax and htis has the effect of reducing lines and wrinkles. It wears off after a few weeks though and has to be repeated. That’s not for me!! So I guess the answer is yes! Neurotoxins could wipe out the earth (although we would all be dead rather than zombies).
I won’t be much more optimistic about nano-technology in the sense that, while it can do amazing things, we now know that the SHAPE of nanoparticles is very important. Roundish nanoparticles are fine but the body does not like long thin nanoparticles as these case physical damage to cells and can lead to cancer and other diseases. We have know this fro some time because it is the long thin minute fibres in asbestos that cause “asbstosis” an incurable lung condition. Now, there is a lot of interest in “nanotubes” , particularly carbon nanotubes as people have done things like put small amounts of iron inside them to creat nanomagnets. These have all sorts of potentially beneficial uses but we still have to be careful about possible health consequences. Like all technologies that are new, we have to tread carefully and not rush headlong after all the benefits we can see without identifying POSSIBLE risks.
However, I am confident that, whatever MIGHT conceivably happen, we won’t actually end up with an apocolypse – zombie or otherwise. At least not these ways………….