For starters, zombies are not out to eat brains that was from a crappy movie with talking zombies. Go to Wikipedia and look up a Cordycep, it's a fungus that causes a zombie-like effect on ants and other bugs, so if people really wanted to we could make a type of bio weapon that could cause a similar effect. It's not full blown zombies but it's pretty close. So I think a Cordycep bio weapon is less far fetch excuse than anything supernatural. Tell me what you think.