11. Which feature of animals that are parasitized is the most difficult for creationist theory to explain?
From Quiz Evidence for Evolution- Parasites
Answer: Animals have defense systems to ward off parasite infestation
Again, creationists believe that since creation, only "devolution" has occurred. In this case, sophisticated immune systems, for example, are very difficult to explain. They are useless- in fact they are harmful- if no parasite infestation exists to be fought. As an example, an immunoglobulin called IgE causes allergic reactions in humans- our bodies react to ragweed pollen, let us say, as a foreign parasite, and the immune system's intense response to "destroy the invader" causes the allergic symptoms we all know and hate. However, IgE serves a very important purpose in much of the world- it also fights multicellular parasites that we rarely encounter in developed countries. In countries without such parasite problems, IgE is a nuisance.
So, immune system responses don't do animals much good if there is no real threat to respond to. Therefore, the creationist must explain where they came from. Did animals have them before the fall, and suffer the allergies and immune-mediated disorders that an under-exercised immune system causes? Or did they come about only after the Fall- in which case, true evolution, as in increasing complexity, did occur?