Seeing the Obvious
Some time ago, I was approached by a person who wanted my thoughts on genetically-engineering grapes so that they produced large amounts of resveratrol.
Mulberries already do.
It’s a bad idea to think about a complex technological solution before looking for an existing, natural, simple solution.
A similar error may have been made in the creation of Golden Rice, particularly as some of the traditional intercropping or ‘hedgerow’ plants once permitted to grow between rice fields in many parts of the Third World are extremely rich in Vitamin A; the replacement of traditional farming methods with ‘Green Revolution’-style cultivars and practices may have been related to the dearth of that substance in the first place.