I am not the OC, but I think he was going on about how you apparently attributed a certain level of "reason" to evolution. His contention is that evolution exists free of reason. I think you two are disagreeing on the term reason.
You mean "reason" in the sense of "why" and he means reason in the sense of "logical conditions". The why is an interesting question, what environmental or other factors provided an advantage in a plant containing this chemical, or was it a non-important side effect of some other change. It is interesting, maybe not easily knowable.
Hope this clears it up. I may be wrong, but I get annoyed when I read comments that are negative without an explanation, so I thought I would attempt to shine some light.
Maybe less "negative" and more "non-constructive". It is a personal annoyance of mine when a reply points out a flaw or misunderstanding, but does so behind a veil of ambiguity. It completely passes up on a chance to educate the OP, and instead leaves them feeling uncertain.
Oh - I was using 'reason' as is often used in the informal vernacular - to mean why or follows from. I assumed that most people on here would understand from the context. But, I can see now that it's a loaded word given the subject - sorry to confuse.