I've always been curious about the evolution of plant products that have pharmaceutical properties. Here we get a not unexpected clue as to how this happens:
Tiger moth caterpillars have been seen medicating themselves to treat a nasty influx of parasites.What is particularly interesting, of course, is what's in it for the plants? I would not be surprised if it turned out the caterpillars in some way actually benefitted those plants -- normally caterpillars are not friends of plants!
Scientists found the caterpillars' sense of taste actually changed when they became infected with parasites.
Instead of avoiding certain alkaloid plants, the caterpillars actually developed a fondness for them.
I wonder how the anti-evolution people deal with this kind of discovery? Ahh, no puzzle really. They just come up with another angle ...