Why does the human body have an immune system that sometimes attacks itself, like in autoimmune diseases?

Question

Why does the human body have an immune system that sometimes attacks itself, like in autoimmune diseases?

In: Biology

Answer 1

Evolution isn’t a process of “this doesn’t help? **Change it!**”

Evolution is a process of “wow that mutant made a ton of babies, guess this is the species now”

Thus, a lot of human systems aren’t “optimized”, they’re just “good enough”. As we live longer and longer lives over the course of our history, we can now see and identify the issues left behind because the system was “good enough”.

*Most* people won’t get an autoimmune disorder, therefore the system is “good enough” to offset the losses