Exactly that. Your body has a defect that causes it to choke itself to death in certain circumstances. And thanks to the evolution, if not for science, the def

Exactly that. Your body has a defect that causes it to choke itself to death in certain circumstances. And thanks to the evolution, if not for science, the defect might be eliminated in a few generations. Or not - perhaps this is an optimal variant of immune the immune system. That is - 90% of organisms will have an excellent immunity, but it will go haywire in 10% of cases, whereas an alternative would be a system with 99% organisms having just an average immune system, but 1% being haywired. Finally, evolution has no "target" or "goal" really. Some features will be broken, and some will be useless. Some may serve a purpose that's beyond our understanding or extremely complex.