I'm planning on writing a story in a post-apocalyptic world where normal humans are hunted by genetically modified predators, both human and otherwise. However, I first actually need to create this post-apocalyptic world, and I'd like it, if possible, to be the result of genetic engineering somehow.
Some details on the pre-apocalyptic genetic engineering scenario:
- GE is still fairly expensive and the domain of the rich - however, some unethical biotech companies offer black market/underground solutions
- For the most part, modifications are used for minor physical attributes - higher cheekbones, better hair, better skin, eye color etc.
- The military has been playing around with animal genes, using it to enhance strength, speed, healing properties, senses etc. in soldiers. However, it's all experimental and in most cases has resulted in adverse effects
- Some of these adverse effects include susceptibility to diseases, partial loss of mental faculties and development of contagious, viral illness
- Animals are occasionally modified too - guard/military dogs for example are made stronger, more intelligent, better sense of smell and hearing etc.
- Some preliminary modification work has been done on cephalopods in order to use them to do underwater deep-sea exploration
Given this scenario, is there a way that rampant genetic engineering could lead to a mass cataclysm scenario, i.e. at least 75% of Earth's population dying (further deaths from the resulting chaos will be there too obviously)?
FINAL EDIT: Will try and be even more specific. I'm looking to add a tragic angle to how this apocalypse comes about. An inadvertent/unwilling twist to end the world. One idea would be that an esteemed geneticist's wife/child/significant other is dying from an incurable disease and the only way to fix him/her is through genetic engineering. Maybe some kind of animal genes are inserted to counteract/fix the damage but a random mutation occurs, turning into an airborne contagion. This is the angle I want to run with and am wondering how plausible it is.