The argument being that plants did not have evolutionary pressure to make their fruits particularly full of vitamins?
Animals have abilities to detect whether what they eat is nutritious, plants give the animals what they want. That includes things like Vitamin C—though that isn’t an essential nutrient for most animals.
As mattnewport mentioned above our ancestors evolved to live on fruits. Most animals can synthesis their own vitamin C. We only lost that ability because our ancestors had so much of it in their diet that they didn’t need to synthesize it.
If fruits didn’t contain vitamin C, we wouldn’t have lost the ability to synthesize it, possibly losing the ability to synthesize something else that they did have.
Animals have abilities to detect whether what they eat is nutritious, plants give the animals what they want. That includes things like Vitamin C—though that isn’t an essential nutrient for most animals.
E.g. see: http://en.wikipedia.org/wiki/Specific_appetite
As mattnewport mentioned above our ancestors evolved to live on fruits. Most animals can synthesis their own vitamin C. We only lost that ability because our ancestors had so much of it in their diet that they didn’t need to synthesize it.
If fruits didn’t contain vitamin C, we wouldn’t have lost the ability to synthesize it, possibly losing the ability to synthesize something else that they did have.