Interesting post.

Whilst most of them seem like common sense, I do wonder about fruit / berries and their seeds. For instance, I often eat apples and like them so much I'll even eat the core. Seeds and all. But the seeds (that I hear contain cyanide) evolved to pass through the guts of herbivores. Hence the fact they're contained inside a juicy apple that evolved to be eaten.

Obviously, I wouldn't recommend chewing apple seeds (or any seed for that matter) so I have to wonder about elderberry seeds, also. Logic would have it that the fruit evolved to be eaten whole, allowing seeds to pass through the gut, carried a distance and dropped in some ready-made fertilizer. It follows that cyanide in seeds could be more intended to stop seed-eating birds from eating a particular species' seed.

What do you think? Any more info here? :)